| 1. |
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| 2. |
- Majdi, Saman, 1977-, et al.
(författare)
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Enhanced Hall mobility in graphene-on-electronic-grade diamond
- 2023
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 123:1
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Tidskriftsartikel (refereegranskat)abstract
- The outstanding electronic properties of graphene make this material a candidate for many applications, for instance, ultra-fast transistors. However, self-heating and especially the detrimental influence of available supporting substrates have impeded progress in this field. In this study, we fabricate graphene-diamond heterostructures by transferring graphene to an ultra-pure single-crystalline diamond substrate. Hall-effect measurements were conducted at 80 to 300 K on graphene Hall bars to investigate the charge transport properties in these devices. Enhanced hole mobility of 2750 cm(2) V-1 s(-1) could be observed at room-temperature when using diamond with reduced nitrogen (N-s(0)) impurity concentration. In addition, by electrostatically varying the carrier concentration, an upper limit for mobility is determined in the devices. The results are promising for enabling carbon-carbon (C-C) devices for room-temperature applications.
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| 3. |
- Asad, Muhammad, 1986, et al.
(författare)
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Enhanced high-frequency performance of top-gated graphene FETs due to substrate-induced improvements in charge carrier saturation velocity
- 2021
-
Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 68:2, s. 899-902
-
Tidskriftsartikel (refereegranskat)abstract
- High-frequency performance of top-gated graphene field-effect transistors (GFETs) depends to a large extent on the saturation velocity of the charge car-riers, a velocity limited by inelastic scattering by surface optical phonons from the dielectrics surrounding the chan-nel. In this work, we show that by simply changing the graphene channel surrounding dielectric with a material having higher optical phonon energy, one could improve the transit frequency and maximum frequency of oscillation of GFETs. We fabricated GFETs on conventional SiO2/Si substrates by adding a thin Al2O3 interfacial buffer layer on top of SiO2/Si substrates, a material with about 30% higher optical phonon energy than that of SiO2, and compared performance with that of GFETs fabricated without adding the interfacial layer. From S-parameter measurements, a transit frequency and a maximum frequency of oscillation of 43 GHz and 46 GHz, respectively, were obtained for GFETs on Al2O3 with 0.5 µm gate length. These values are approximately 30% higher than those for state-of-the-art GFETs of the same gate length on SiO2. For relating the improvement of GFET high-frequency performance to improvements in the charge carrier saturation velocity, we used standard methods to extract the charge carrier veloc-ity from the channel transit time. A comparison between two sets of GFETs with and without the interfacial Al2O3 layer showed that the charge carrier saturation velocity had increased to 2·10^7 cm/s from 1.5·10^7 cm/s.
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| 4. |
- Asad, Muhammad, 1986, et al.
(författare)
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The dependence of the high-frequency performance of graphene field-effect transistors on channel transport properties
- 2020
-
Ingår i: IEEE Journal of the Electron Devices Society. - 2168-6734. ; 8, s. 457-464
-
Tidskriftsartikel (refereegranskat)abstract
- This paper addresses the high-frequency performance limitations of graphene field-effect transistors (GFETs) caused by material imperfections. To understand these limitations, we performed a comprehensive study of the relationship between the quality of graphene and surrounding materials and the high-frequency performance of GFETs fabricated on a silicon chip. We measured the transit frequency (fT) and the maximum frequency of oscillation (fmax) for a set of GFETs across the chip, and as a measure of the material quality, we chose low-field carrier mobility. The low-field mobility varied across the chip from 600 cm2/Vs to 2000 cm2/Vs, while the fT and fmax frequencies varied from 20 GHz to 37 GHz. The relationship between these frequencies and the low-field mobility was observed experimentally and explained using a methodology based on a small-signal equivalent circuit model with parameters extracted from the drain resistance model and the charge-carrier velocity saturation model. Sensitivity analysis clarified the effects of equivalent-circuit parameters on the fT and fmax frequencies. To improve the GFET high-frequency performance, the transconductance was the most critical parameter, which could be improved by increasing the charge-carrier saturation velocity by selecting adjacent dielectric materials with optical phonon energies higher than that of SiO2.
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| 5. |
- Auriacombe, Olivier, 1989, et al.
(författare)
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325 GHz and 650 GHz Dual-polarisation receivers Concept
- 2022
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Ingår i: 32nd International Symposium of Space Terahertz Technology, ISSTT 2022.
-
Konferensbidrag (refereegranskat)abstract
- The integrated dual-polarisation receivers utilize a dual probe concept, efficiently integrating the antenna and MMIC package environment which allows for polarisation discrimination without the use of bulky and lossy external orthomode transducers. This concept increases the sensitivity of the instrument and reduces its size, enabling the development of future earth observation arrays. Omnisys Instruments AB (Sweden) and Chalmers University of Technology (Sweden) are working to demonstrate state-of-the-art dual polarisation capability with two integrated receiver modules at 325 GHz and 650 GHz.
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| 6. |
- Blomberg, Patrik, 1992, et al.
(författare)
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On-wafer characterisation of resonant-tunnelling diodes up to 1.1 THz
- 2023
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035.
-
Konferensbidrag (refereegranskat)abstract
- This paper presents on-wafer S-parameter characterisation of resonant-tunnelling diodes between 0.5 THz and 1.1 THz. Diodes with a peak current density of 532 kA/cm2 and a clear negative differential region have been fabricated. An on-chip Multi-Thru-Reflect-Line calibration kit was developed and utilised to achieve accurate S-parameter measurements up to 1.1 THz.
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| 7. |
- Bonmann, Marlene, 1988, et al.
(författare)
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Effects of self-heating on fT and fmax performance of graphene field-effect transistors
- 2020
-
Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 67:3, s. 1277-1284
-
Tidskriftsartikel (refereegranskat)abstract
- It has been shown that there can be a significant temperature increase in graphene field-effect transistors (GFETs) operating under high drain bias, which is required for power gain. However, the possible effects of self-heating on the high-frequency performance of GFETs have been weakly addressed so far. In this article, we report on an experimental and theoretical study of the effects of self-heating on dc and high-frequency performance of GFETs by introducing a method that allows accurate evaluation of the effective channel temperature of GFETs with a submicrometer gate length. In the method, theoretical expressions for the transit frequency (fT) and the maximum frequency of oscillation (fmax) based on the small-signal equivalent circuit parameters are used in combination with the models of the field- and temperature-dependent charge carrier concentration, velocity, and saturation velocity of GFETs. The thermal resistances found by our method are in good agreement with those obtained by the solution of the Laplace equation and by the method of thermo-sensitive electrical parameters. Our experiments and modeling indicate that the self-heating can significantly degrade the fT and fmax of GFETs at power densities above 1 mW/μm², from approximately 25 to 20 GHz. This article provides valuable insights for further development of GFETs, taking into account the self-heating effects on the high-frequency performance.
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| 8. |
- Bonmann, Marlene, 1988, et al.
(författare)
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Sub-millimetre wave range-Doppler radar as a diagnostic tool for gas-solids systems - solids concentration measurements
- 2023
-
Ingår i: Advanced Powder Technology. - : Elsevier BV. - 0921-8831 .- 1568-5527. ; 34:1
-
Tidskriftsartikel (refereegranskat)abstract
- Current non-intrusive measurement techniques for characterising the solids flow in gas-solids suspensions are limited by the low temporal or low spatial resolution of the sample volume, or in the case of optical methods, by a short range of sight. In this work, a sub-millimetre wave range-Doppler radar is developed and validated for non-intrusive sensing of solids concentrations in a gas-solids particle system with known characteristics. The radar system combines favourable features, such as the ability to see through at optical frequencies opaque materials, to measure the local solids velocity and the reflected radar power with a spatial resolution of a few cubic centimetres over distances of a few metres. In addition, the radar hardware offers flexibility in terms of installation. After signal processing, the output of the radar is range-velocity images of the solids flowing along the radar’s line-of-sight. The image frame rate can be close to real-time, allowing the solids flow dynamics to be observed. While the well-established Doppler principle is used to measure the solids velocity, this paper introduces a method to relate the received radar signal power to the solids volumetric concentrations (cv) of different particulate materials. The experimental set-up provides a steady stream of free-falling solids that consist of glass spheres, bronze spheres or natural sand grains with known particle size distributions and with particle diameters in the range of 50–300 µm. Thus, the values of cv found using the radar measurements are validated using the values of cv retrieved from closure of the mass balance derived from the measured mass flow rate of the solids stream and the solids velocity. The results show that the radar system provides reliable measurements of cv, with a mean relative error of approximately 25 % for all the tested materials, particle sizes and mass flow rates, yielding values of cv ranging from 0.2 × 10-4 m3/m3 up to 40 × 10-4 m3/m3 and solids velocities within the range of 0–4.5 m/s. This demonstrates the ability of the radar technology to diagnose the solids flow in gas-solids suspensions using a unique combination of penetration length, accuracy, and spatial and time resolution. In future work, the radar technique will be applied to study non-controlled solids flow at a larger scale, and to understand flow conditions relevant to industrial reactor applications, e.g., fluidised bed, entrained flow, and cyclone units.
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| 9. |
- Bonmann, Marlene, 1988, et al.
(författare)
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Terahertz radar observes powder dynamics for pharmaceutical manufacturing
- 2024
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Ingår i: IEEE Sensors Journal. - 1558-1748 .- 1530-437X. ; 24:13, s. 20512-20522
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Tidskriftsartikel (refereegranskat)abstract
- The optical opaqueness of powders has precluded the observation of powder flow dynamics in processing tubes, with important implications, for example, in the pharmaceutical industry, where non-destructive monitoring during the manufacturing process is essential to ensure the quality of the final product and the effectiveness of the process. Taking advantage of the high penetration of terahertz electromagnetic waves in powders and its wavelength-to-particle size ratio, we demonstrate that a submillimeter-wave pulse-Doppler radar can overcome the present challenges and characterize powder flow dynamics in pharmaceutical manufacturing processes. Mimicking typical vessel shapes in pharmaceutical operations, we were able to characterize falling powder streams in a tube with a sample volume resolution of a few cubic centimeters and a range resolution of about 5 mm. We successfully monitored particle velocity, particle distribution within the tube, and mass flow rate in real-time. This remote sensing method, based on advanced terahertz electronics, opens up the possibility to study and monitor powder dynamics in a wide range of applications.
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| 10. |
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| 11. |
- Bryllert, Tomas, 1974, et al.
(författare)
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A Submillimeter-Wave FMCW Pulse-Doppler Radar to Characterize the Dynamics of Particle Clouds
- 2023
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 13:4, s. 389-395
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a 340-GHz frequency-modulated continuous-wave (FMCW) pulse-Doppler radar. The radar system is based on a transceiver module with about one milli-Watt output power and more than 30-GHz bandwidth. The front-end optics consists of an off-axis parabola fed by a horn antenna from the transceiver unit, resulting in a collimated radar beam. The digital radar waveform generation allows for coherent and arbitrary FMCW pulse waveforms. The performance in terms of sensitivity and resolution (range/cross-range/velocity) is demonstrated, and the system's ability to detect and map single particles (0.1–10 mm diameter), as well as clouds of particles, at a 5-m distance, is presented. A range resolution of ca 1 cm and a cross-range resolution of a few centimeters (3-dB beam-width) allow for the characterization of the dynamics of particle clouds with a measurement voxel size of a few cubic centimeters. The monitoring of particle dynamics is of interest in several industrial applications, such as in the manufacturing of pharmaceuticals and the control/analysis of fluidized bed combustion reactors.
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| 12. |
- Cabello Sánchez, Juan, 1992, et al.
(författare)
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A Capacitive-Gap Coupled Terahertz Planar-Goubau-Line Power Divider
- 2023
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 13:6, s. 698-703
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Tidskriftsartikel (refereegranskat)abstract
- The planar Goubau line is a single-conductor waveguide with a low attenuation constant at terahertz frequencies compared to other planar waveguides. However, its single-conductor nature complicates the design of circuit elements compared to multi-conductor waveguides, especially when impedance transformation is needed, like in the case of power dividers. In this paper, we present a power divider for a planar Goubau line based on capacitive-gap coupled lines, providing a matched input port. A 900-GHz equal power divider was fabricated on a suspended silicon membrane and was characterized with a Vector Network Analyzer and terahertz probes between 0.5 THz and 1.1 THz. Simulations and measurements are in good agreement, the measured input return loss is lower than 15dB at the design frequency, and the average coupler loss is estimated to be lower than 1 dB when de-embedding the feeding lines.
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| 13. |
- Cabello Sánchez, Juan, 1992, et al.
(författare)
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A Corrugated Planar-Goubau-Line Termination for Terahertz Waves
- 2023
-
Ingår i: IEEE Microwave and Wireless Technology Letters. - 2771-957X .- 2771-9588. ; 33:6, s. 643-646
-
Tidskriftsartikel (refereegranskat)abstract
- The planar Goubau line is a promising low-loss metal waveguide for terahertz applications. To enable advanced circuits and multi-port measurements based on planar Goubau lines, there is a strong need for broadband impedance-matched loads, which can be used to absorb the energy and minimize standing waves in a system. In this work, we propose a termination for planar Goubau lines based on an exponentially-tapered corrugated line, gradually increasing conductor losses while maintaining small reflections. The corrugation density is high enough to increase conductor losses without requiring an auxiliary low-conductivity material. A 400-µm long planar Goubau line load was fabricated on a 10-µm thick silicon substrate suspended in the air. Simulations of the load show excellent agreement with calibrated reflection measurements in the frequency range 0.5 THz – 1.1 THz. Above the cut-off frequency of around 580 GHz, the measured reflections are less than -19 dB, below the noise floor of the characterization setup.
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| 14. |
- Cabello Sánchez, Juan, 1992, et al.
(författare)
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Capacitively-coupled resonators for terahertz planar-Goubau-line filters
- 2023
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 13:1, s. 58-66
-
Tidskriftsartikel (refereegranskat)abstract
- Low-loss planar Goubau lines show promising potential for terahertz applications. However, a single-wire waveguide exhibits less design freedom than standard multi-conductor lines, which is a significant constraint for realizing standard components. Existing filters for planar Goubau line lack clear design procedures preventing the synthesis of an arbitrary filter response. In this work, we present a design for a bandpass/bandstop filter for planar Goubau line by periodically loading the line with capacitively-coupled ?∕2 resonators, which can be easily tuned by changing their electrical length. The filter’s working principle is explained by a proposed transmission-line model. We designed and fabricated a passband filter centered at 0.9 THz on a 10-?m silicon-membrane substrate and compared measurement results between 0.5 THz and 1.1 THz to electromagnetic simulations, showing excellent agreement in both ?11 and ?21. The measured passband has an insertion loss of 7 dB and a 3-dB bandwidth of 31%. Overall, the proposed filter design has good performance while having a simple design procedure.
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| 15. |
- Cabello Sánchez, Juan, 1992, et al.
(författare)
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On-Chip Characterization of High-Loss Liquids Between 750 and 1100 GHz
- 2021
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 11:1, s. 113-116
-
Tidskriftsartikel (refereegranskat)abstract
- Terahertz spectroscopy is a promising tool for analyzing the picosecond dynamics of biomolecules, which is influenced by surrounding water molecules. However, water causes extreme losses to terahertz signals, preventing sensitive measurements at this frequency range. Here, we present sensitive on-chip terahertz spectroscopy of highly lossy aqueous solutions using a vector network analyzer, contact probes, and a coplanar waveguide with a 0.1 mm wide microfluidic channel. The complex permittivities of various deionized water/isopropyl alcohol concentration are extracted from a known reference measurement across the frequency range 750–1100 GHz and agrees well with literature data. The results prove the presented method as a highsensitive approach for on-chip terahertz spectroscopy of high-loss liquids, capable of resolving the permittivity of water.
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| 16. |
- Cabello Sánchez, Juan, 1992, et al.
(författare)
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Terahertz Planar Goubau Line Components on Thin Suspended Silicon Substrate
- 2022
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; August
-
Konferensbidrag (refereegranskat)abstract
- The planar Goubau line is a low-loss planar single-conductor waveguide that holds promise for terahertz applications, where power efficiency is crucial. We present three circuit elements for planar Goubau line: a stopband filter, a matching load, and a power divider, which have been fabricated in a high-resistivity silicon membrane. Simulation results are presented for the matching load and the power divider. The filter’s performance is validated by comparing measurement results with simulations, showing good agreement.
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| 17. |
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| 18. |
- Drakinskiy, Vladimir, 1977, et al.
(författare)
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Reliability study of THz Schottky mixers and HBV frequency multipliers for space applications
- 2020
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Ingår i: Proceedings of the 31st Symposium on Space Terahertz Technology, ISSTT 2020. ; , s. 118-
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Konferensbidrag (refereegranskat)abstract
- We report status and current results of the preliminary reliability study on 300 GHz InP heterostructure barrier varactor diode multipliers and 1200 GHz GaAs Schottky diode mixers. Both types of diodes are monolithically integrated with circuits and were processed on 3" InP and GaAs wafers respectively using established III-V processing. We will present results on thermal step-stress tests up to 300oC, indicating the operational temperature limitations of the devices. Also, the analysis of the accelerated lifetime testing (1000h) will be discussed.
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| 19. |
- Feijoo, Pedro C., et al.
(författare)
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Does carrier velocity saturation help to enhance fmax in graphene field-effect transistors?
- 2020
-
Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 2:9, s. 4179-4186
-
Tidskriftsartikel (refereegranskat)abstract
- It has been argued that current saturation in graphene field-effect transistors (GFETs) is needed to get optimal maximum oscillation frequency (f(max)). This paper investigates whether velocity saturation can help to get better current saturation and if that correlates with enhancedf(max). We have fabricated 500 nm GFETs with high extrinsicf(max)(37 GHz), and later simulated with a drift-diffusion model augmented with the relevant factors that influence carrier velocity, namely: short-channel electrostatics, saturation velocity effect, graphene/dielectric interface traps, and self-heating effects. Crucially, the model provides microscopic details of channel parameters such as carrier concentration, drift and saturation velocities, allowing us to correlate the observed macroscopic behavior with the local magnitudes. When biasing the GFET so all carriers in the channel are of the same sign resulting in highly concentrated unipolar channel, we find that the larger the drain bias is, both closer the carrier velocity to its saturation value and the higher thef(max)are. However, the highestf(max)can be achieved at biases where there exists a depletion of carriers near source or drain. In such a situation, the highestf(max)is not found in the velocity saturation regime, but where carrier velocity is far below its saturated value and the contribution of the diffusion mechanism to the current is comparable to the drift mechanism. The position and magnitude of the highestf(max)depend on the carrier concentration and total velocity, which are interdependent and are also affected by the self-heating. Importantly, this effect was found to severely limit radio-frequency performance, reducing the highestf(max)from similar to 60 to similar to 40 GHz.
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| 20. |
- Generalov, Andrey, 1987, et al.
(författare)
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Distinction of the thermoelectric effect in graphene FET THz detectors
- 2020
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 504-505
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Konferensbidrag (refereegranskat)abstract
- This work presents an approach to distinguish the thermoelectric detection mechanism from the resistive mixing or plasma wave rectification in graphene FET THz detectors. Numerical full-wave simulations validate the asymmetric feeding of the existing antenna design and allow for comparison with a reference design of thermoelectric detectors. The experimental results verify quantitively the thermoelectric contribution to the overall rectification, which allows for more accurate modelling of the GFET THz detectors.
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| 21. |
- Guio Perez, Diana Carolina, 1985, et al.
(författare)
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Radar-based measurements of the solids flow in a circulating fluidized bed
- 2023
-
Ingår i: Fuel. - 0016-2361. ; 345
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this work is to demonstrate the value of radar technology for studying experimentally the solids flows in gas-solids fluidized beds. The work presents original results regarding the solids concentration and velocity acquired in a non-intrusive manner from a cold flow model. The tailored radar setup operates at submillimeter wave frequencies (0.34 THz) and can measure the location of solids with a spatial resolution of 1/8 mm−1 in the direction of the radar beam, and of 40–60 mm across the radar beam. The solids velocity in the direction of the beam propagation is determined through measurement of the Doppler shift caused by the reflection of the transmitted radar signal by solids moving in relation to the antenna. The measurements were performed in both the horizontal and vertical directions in the riser of a circulating fluidized bed (cross-sectional area of 0.45 m2 and height of 3.1 m) operated with glass beads (mean particle size of 106 µm, and particle density of 2,486 kg/m3) and using air at ambient temperature as the fluidization agent, with superficial velocities in the range of 0.3–1.3 m/s. The measurements are used to assess the validity of the technique and are not intended to characterize the unit fluid dynamically. The solids concentrations derived from the radar measurements follow the qualitative trends derived from pressure-drop measurements, resembling the expected changes that occur in the concentration profiles as the fluidization velocity increases. Concentrations in the range from 10-6 m3/m3 to 10-1 m3/m3 are measurable. In quantitative terms, for low concentrations of solids (<5·10-3 m3/m3, approximately) the radar measurements exhibited the ability to provide more consistent measurements of the solids concentration than those obtained from pressure transducers, for which the small pressure differences lead to unstable and even negative values for solids concentrations. The two measurement methods were in quantitative agreement for solids volume fractions higher than the threshold. Concentrations ≥ 1·10-1 m3/m3, though measurable, strongly attenuate the radar signal, thereby reducing the beam penetration to a depth of centimeters. For each position along the radar beam, the distribution of solids velocity measured from the Doppler effect was found to be within the expected ranges and allowed observations of solids back-mixing. The radar technique applied in this work is a promising technique for detailed characterization of the solids flow in fluidized beds, offering high spatial and temporal resolutions, allowing the determination of both solids velocity and concentration, and having a reasonably high penetration depth.
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| 22. |
- Hamed, Ahmed, et al.
(författare)
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Integrated 10-GHz Graphene FET Amplifier
- 2021
-
Ingår i: IEEE Journal of Microwaves. - 2692-8388. ; 1:3, s. 821-826
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Tidskriftsartikel (refereegranskat)abstract
- Graphene has unique electrical and mechanical properties which can pave the way for new types of devices for microwave applications. However, emerging technologies often have problems with yield and still considerable variation in device parameters cause great challenges for circuit design. In this paper, we present the design and development of an integrated graphene FET amplifier addressing this challenge. A representative graphene FET was selected from a set of devices and then the input and output matching circuits were designed using the negative-image technique. The two-finger GFET with a gate length of 0.5 μ m exhibit a typical fT and fmax of 35 GHz and 37 GHz, respectively. The integrated graphene FET amplifier was fabricated on a high-resistivity silicon substrate together with thin film capacitors, airbridges, and spiral inductors. A record high gain of 4.2 dB at 10.6 GHz was measured for a single transistor amplifier stage and agrees well with simulations. These results indicate significant progress towards active microwave circuits based on emerging 2D materials.
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| 23. |
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| 24. |
- Hemmeter, Andreas, et al.
(författare)
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Terahertz Rectennas on Flexible Substrates Based on One-Dimensional Metal–Insulator–Graphene Diodes
- 2021
-
Ingår i: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 3:9, s. 3747-3753
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Tidskriftsartikel (refereegranskat)abstract
- Flexible energy harvesting devices fabricated in scalable thin-film processes are crucial for wearable electronics and the Internet of Things. We present a flexible rectenna based on a one-dimensional junction metal–insulator–graphene diode, offering low-noise power detection at terahertz (THz) frequencies. The rectennas are fabricated on a flexible polyimide film in a scalable process by photolithography using graphene grown by chemical vapor deposition. A one-dimensional junction reduces the junction capacitance and enables operation up to 170 GHz. The rectenna shows a maximum responsivity of 80 V/W at 167 GHz in free space measurements and minimum noise equivalent power of 80 pW/√Hz.
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| 25. |
- Jayasankar, Divya, 1994, et al.
(författare)
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4.7-THz Schottky Diode Harmonic Mixer: Design, Fabrication, and Performance Optimization
- 2024
-
Ingår i: ISSTT 2024 - 33rd International Symposium on Space Terahertz Technology.
-
Konferensbidrag (refereegranskat)abstract
- This paper focuses on the ongoing development of supra-THz harmonic mixers at Chalmers University of Technology. The planar, single-ended, x8-harmonic mixers based on Schottky-barrier diodes were realized on a 2-um GaAs substrate with integrated pyramidal horn. In contrast to our previous design with a diagonal horn, the new design addresses sensitivity to E-plane misalignment, which previously compromised mixer performance. The availability of THz harmonic frequency converters operating at ambient temperature is pivotal in realizing high-resolution THz heterodyne receivers.
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| 26. |
- Jayasankar, Divya, et al.
(författare)
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A 3.5-THz, ×6-Harmonic, Single-Ended Schottky Diode Mixer for Frequency Stabilization of Quantum-Cascade Lasers
- 2021
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - : IEEE Microwave Theory and Techniques Society. - 2156-342X .- 2156-3446. ; 11:6, s. 684-694
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and compact frequency converters are essential for frequency stabilization of terahertz sources. In this article, we present a 3.5-THz, × 6-harmonic, integrated Schottky diode mixer operating at room temperature. The designed frequency converter is based on a single-ended, planar Schottky diode with a submicron anode contact area defined on a suspended 2-μ m ultra-thin gallium arsenide substrate. The dc-grounded anode pad was combined with the radio frequency E-plane probe, which resulted in an electrically compact circuit. At 200-MHz intermediate frequency, a mixer conversion loss of about 59 dB is measured resulting in a 40-dB signal-to-noise ratio for phase locking a 3.5-THz quantum-cascade laser. Using a quasi-static diode model combined with electromagnetic simulations, good agreement with the measured results was obtained. Harmonic frequency converters without the need of cryogenic cooling will help in the realization of highly sensitive space and air-borne heterodyne receivers.
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| 27. |
- Jayasankar, Divya, 1994, et al.
(författare)
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A 4.7-THz fundamental Schottky diode mixer
- 2022
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2022-August
-
Konferensbidrag (refereegranskat)abstract
- Fundamental mixers operating at ambient temperatures are essential for realising long-lifetime space missions aiming to measure gas spectra at terahertz frequencies. This paper presents the design and sensitivity analysis of a 4.7-THz fundamental mixer. At supra-THz frequencies, fabrication and assembly tolerances substantially affect the mixer performance, and it is essential to identify critical circuit parameters. This work presents the progress towards a room-temperature heterodyne supra-terahertz receiver.
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| 28. |
- Jayasankar, Divya, 1994, et al.
(författare)
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A Broadband Conversion Loss Measurement Technique for Terahertz Harmonic Mixers
- 2024
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 14:3, s. 424-427
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents an experimental characterization technique for assessing the performance of terahertz harmonic mixers across a wide frequency range. The total signal transfer loss of three mixers was measured in both up- and down-conversion configurations, and the conversion loss was determined through the solution of a linear system of equations. The proposed method uses LO signals with a frequency offset to ensure single sideband measurements, thereby eliminating the need for image-reject filters. The three-mixer method was verified by measurements of millimeter-wave mixers, which matched the traditional characterization method using a calibrated source and power meter. Given this successful millimeter-wave demonstration, we characterized three WM-86 Schottky diode ×4-harmonic mixers from 2.2 to 3 THz. This technique presents a notable advantage for conducting broadband mixer characterizations, particularly in the terahertz frequency regime which lacks tunable, wide-band sources.
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| 29. |
- Jayasankar, Divya, 1994, et al.
(författare)
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Design and Characterisation of a 3.5-THz Fundamental Schottky Mixer
- 2022
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Ingår i: 32nd International Symposium of Space Terahertz Technology, ISSTT 2022.
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Konferensbidrag (refereegranskat)abstract
- Mixers operating at ambient temperatures are essential for realisation of THz heterodyne receivers for long lifetime space missions. In this paper, we report the design, circuit and block fabrication, assembly and characterisation of a 3.5-THz fundamental Schottky diode mixer. Design of planar, integrated mixer circuit realised using a suspended stripline technology on a 2-µm GaAs substrate and video signal detection results are presented.
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| 30. |
- Jayasankar, Divya, et al.
(författare)
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Design and development of 3.5 THz Schottky-based fundamental mixer
- 2021
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Ingår i: 2020 50th European Microwave Conference, EuMC 2020. - : Institute of Electrical and Electronics Engineers Inc.. - 9782874870590 ; , s. 595-598
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Konferensbidrag (refereegranskat)abstract
- Broadband Schottky diode mixers operating at room-temperature are crucial for terahertz heterodyne instrumentation in space-borne applications. In this paper, we present the design of a compact 3.5 THz fundamental single-ended Schottky diode mixer. The design is based on Schottky diodes with a sub-micron anode area, defined using nanolithography techniques, and integrated with suspended strip lines on an ultra-thin GaAs-membrane.
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| 31. |
- Jayasankar, Divya, 1994, et al.
(författare)
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Development of Supra-THz Schottky Diode Harmonic Mixers
- 2021
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781728194240 ; 2021-August
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Konferensbidrag (refereegranskat)abstract
- In this paper, we report the development of single-ended, Schottky diode-based harmonic mixers operating at 3.5 THz and 4.7 THz, respectively. Both mixers utilize a sub-micron size Schottky diode fabricated with circuit elements on a suspended 2 um-thick GaAs stripline circuit and then assembled in a waveguide split-block. The diode is closely integrated with the RF-waveguide, resulting in an electrically small and compact circuit. For the 3.5-THz, x6-harmonic mixer, a conversion loss of about 60 dB was measured at an intermediate frequency (IF) of 200 MHz. The predicted mixer performance versus dc bias agrees well with the measurements. Based on these results, the preliminary design and simulation results of a 4.7-THz, x8-harmonic mixer, are presented.
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| 32. |
- Jayasankar, Divya, et al.
(författare)
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Investigation of Hydrogel Skin Phantoms Using Terahertz Time-domain Spectroscopy
- 2022
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Ingår i: 2022 52nd European Microwave Conference, EuMC 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9782874870699 ; , s. 401-403
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Konferensbidrag (refereegranskat)abstract
- Human skin phantoms are essential to enable fast, label-free, and reliable testing of pharmaceutical and cosmetic products. We report the characterisation of polyvinyl alcohol-based hydrogel phantoms along with in-vivo skin measurements of three volunteers from 0.2 to 1 THz. The results indicate that frequency-dependent properties of hydrogel phantoms are similar to human skin and show promising prospects of being utilised as a skin equivalent.
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| 33. |
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| 34. |
- Jensen, Maja, 1978, et al.
(författare)
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High-resolution macromolecular crystallography at the FemtoMAX beamline with time-over-threshold photon detection
- 2021
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Ingår i: Journal of Synchrotron Radiation. - 1600-5775 .- 0909-0495. ; 28, s. 64-70
-
Tidskriftsartikel (refereegranskat)abstract
- Protein dynamics contribute to protein function on different time scales. Ultrafast X-ray diffraction snapshots can visualize the location and amplitude of atom displacements after perturbation. Since amplitudes of ultrafast motions are small, high-quality X-ray diffraction data is necessary for detection. Diffraction from bovine trypsin crystals using single femtosecond X-ray pulses was recorded at FemtoMAX, which is a versatile beamline of the MAX IV synchrotron. The time-over-threshold detection made it possible that single photons are distinguishable even under short-pulse low-repetition-rate conditions. The diffraction data quality from FemtoMAX beamline enables atomic resolution investigation of protein structures. This evaluation is based on the shape of the Wilson plot, cumulative intensity distribution compared with theoretical distribution, I/σ, Rmerge /Rmeas and CC1/2 statistics versus resolution. The FemtoMAX beamline provides an interesting alternative to X-ray free-electron lasers when studying reversible processes in protein crystals.
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| 35. |
- Jeppson, Kjell, 1947, et al.
(författare)
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Mobility degradation and series resistance in graphene field-effect transistors
- 2021
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Ingår i: IEEE Transactions on Electron Devices. - 1557-9646 .- 0018-9383. ; 68:6, s. 3091-3095
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate device models and parameter extraction methods are of utmost importance for characterizing graphene field-effect transistors (GFETs) and for predicting their performance in circuit applications. For DC characterization, accurate extraction of mobility and series resistance is of particular concern. In this paper, we show how a first-order mobility degradation model can be used to separate information about mobility degradation and series resistance for a set of GFETs of different channel lengths. Data from a large set of top-gated GFETs based on chemical vapor deposited (CVD) graphene was analyzed to validate the proposed model and extraction procedures. For removing any uncertainties caused by observed device-to-device data variations due to the uneven quality of CVD graphene, the same methods were applied to a set of closely located bottom-gated GFETs found in literature. Those GFETs were designed for transfer length methods and fabricated on exfoliated graphene of homogenous quality. Similar mobility degradation behavior was observed for both sets of devices with the mobility being reduced to half for a voltage-induced charge carrier density of 1013 cm-2.
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| 36. |
- Masyukov, Maxim, et al.
(författare)
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A calibration-free method to assess the quality of standards for THz on-wafer measurements
- 2022
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2022-August
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Konferensbidrag (refereegranskat)abstract
- A method to assess the quality of the calibration standards has been developed and tested. The actual response of the tested transmission lines for LRRM-16 calibration approach has been simulated in HFSS environment, fabricated, and tested with on-wafer measurement setup. The method for quality assessment is based on the properties of similar matrices, that compares traces and determinants of the S-parameters products for fabricated and simulated structures.
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| 37. |
- Moradikouchi, Anis, 1990, et al.
(författare)
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Monitoring the Porosity of Pharmaceutical Tablets Using THz Frequency Domain Spectroscopy
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, terahertz frequency domain spectroscopy (THz-FDS) in transmission mode has been employed to study the impact of design parameters of tablets such as initial particle size, drug concentration and compaction force, on their porosity. The complex transmission coefficient S21 of 69 tablets were measured using a vector network analyzer in the frequency range of 500-750 GHz. The results show that excipient particle size and compaction force have significant effects on the pore structure of the tablets and THz-FDS reveals to be a very promising tool in monitoring the porosity of pharmaceutical tablets.
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| 38. |
- Moradikouchi, Anis, 1990, et al.
(författare)
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Small Variation of Active Pharmaceutical Ingredient Concentration Can Be Observed with THz Frequency Domain Spectroscopy
- 2021
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2021-August
-
Konferensbidrag (refereegranskat)abstract
- Terahertz frequency-domain spectroscopy (THz-FDS) has been employed to study the result of the variation of active pharmaceutical ingredients (API) on the effective refractive index of pharmaceutical tablets. A quasi-optical set-up with four off-axis parabolic mirrors was used to measure the effective refractive index of tablets in the frequency range of 500-750 GHz. It was observed that a small variation in API concentration can be detected using accurate measurements of the complex transmission coefficients. As a result, THz-FDS reveals to be an effective technique in monitoring the physical properties of pharmaceutical tablets
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| 39. |
- Moradikouchi, Anis, 1990, et al.
(författare)
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Terahertz Frequency-Domain Sensing Combined with Quantitative Multivariate Analysis for Pharmaceutical Tablet Inspection
- 2023
-
Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 632
-
Tidskriftsartikel (refereegranskat)abstract
- Near infrared (NIR) and Raman spectroscopy combined with multivariate analysis are established techniques for the identification and quantification of chemical properties of pharmaceutical tablets like the concentration of active pharmaceutical ingredients (API). However, these techniques suffer from a high sensitivity to particle size variations and are not ideal for the characterization of physical properties of tablets such as tablet density. In this work, we have explored the feasibility of terahertz frequency-domain spectroscopy, with the advantage of low scattering effects, combined with multivariate analysis to quantify API concentration and tablet density. We studied 33 tablets, consisting of Ibuprofen, Mannitol, and a lubricant with API concentration and filler particle size as the design factors. The terahertz signal was measured in transmission mode across the frequency range 750 GHz to 1.5 THz using a vector network analyzer, frequency extenders, horn antennas, and four off-axis parabolic mirrors. The attenuation spectral data were pre-processed and orthogonal partial least square (OPLS) regression was applied to the spectral data to obtain quantitative prediction models for API concentration and tablet density. The performance of the models was assessed using test sets. While a fair model was obtained for API concentration, a high-quality model was demonstrated for tablet density. The coefficient of determination (?2) for the calibration set was 0.97 for tablet density and 0.98 for API concentration, while the relative prediction errors for the test set were 0.7% and 6% for tablet density and API concentration models, respectively. In conclusion, terahertz spectroscopy demonstrated to be a complementary technique to Raman and NIR spectroscopy, which enables the characterization of physical properties of tablets like tablet density, and the characterization of API concentration with the advantage of low scattering effects.
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| 40. |
- Moradikouchi, Anis, 1990, et al.
(författare)
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Terahertz Frequency Domain Sensing for Fast Porosity Measurement of Pharmaceutical Tablets
- 2022
-
Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 618
-
Tidskriftsartikel (refereegranskat)abstract
- Porosity is an important property of pharmaceutical tablets since it may affect tablet disintegration, dissolution, and bio-availability. It is, therefore, essential to establish non-destructive, fast, and compact techniques to assess porosity, in-situ, during the manufacturing process. In this paper, the terahertz frequency-domain (THz-FD) technique was explored as a fast, non-destructive, and sensitive technique for porosity measurement of pharmaceutical tablets. We studied a sample set of 69 tablets with different design factors, such as particle size of the active pharmaceutical ingredient (API), Ibuprofen, particle size of the filler, Mannitol, API concentration, and compaction force. The signal transmitted through each tablet was measured across the frequency range 500-750 GHz using a vector network analyzer combined with a quasi-optical set-up consisting of four off-axis parabolic mirrors to guide and focus the beam. We first extracted the effective refractive index of each tablet from the measured complex transmission coefficients and then translated it to porosity, using an empirical linear relation between effective refractive index and tablet density. The results show that the THz-FD technique was highly sensitive to the variations of the design factors, showing that filler particle size and compaction force had a significant impact on the effective refractive index of the tablets and, consequently, porosity. Moreover, the fragmentation behavior of particles was observed by THz porosity measurements and was verified with scanning electron microscopy of the cross-section of tablets. In conclusion, the THz-FD technique, based on electronic solutions, allows for fast, sensitive, and non-destructive porosity measurement that opens for compact instrument systems capable of in-situ sensing in tablet manufacturing.
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| 41. |
- Moradikouchi, Anis, 1990, et al.
(författare)
-
Terahertz radar sensing for real-time monitoring of powder streams
- 2023
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035.
-
Konferensbidrag (refereegranskat)abstract
- In pharmaceutical manufacturing processes, the flow properties of powder streams moving in the manufacturing pipes directly impact the properties of the final drug product, and there is a need for real-time non-invasive monitoring of the powder flow properties with process analytical tools. In this study, we propose a frequency-modulated continuous wave (FMCW) Doppler radar system with a center frequency of 340 GHz to measure the flow properties of falling powder streams in a vertical transparent tube. We successfully measured the velocity profile and powder flow density variation along the height of the tube with a spatial resolution of about 5 mm. In conclusion, the terahertz FMCW Doppler radar system was shown to be highly promising for real-time sensing of flow properties of powder streams in the pharmaceutical manufacturing processes.
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| 42. |
- Nefedova, Irina, et al.
(författare)
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Design of a quasioptical test bench for VNA extenders
- 2020
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 552-553
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Konferensbidrag (refereegranskat)abstract
- The CAD design, simulated optical performance, and test measurements of a quasioptical test bench for VNA extenders are presented. The system allows straightforward integration of off axis parabolic mirrors and VNA extenders. The mirror orientation reduces aberrations and results suggest optical properties are close to what is expected with geometric ray tracing.
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| 43. |
- Nefedova, Irina, et al.
(författare)
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THz Frequency Quantification of Water Gradients in Drying Paper
- 2020
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2020-November, s. 844-845
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Konferensbidrag (refereegranskat)abstract
- THz-reflection spectroscopy was used to extract time-varying water gradients in drying paper targets mounted on electrically thick dielectric substrates. The data showed a pronounced and prolonged drop below dry reflectivity when the water content that peaks at low weight (∼10%). A binomial distribution fitted to the acquired data confirms the existence of the time-varying water content gradient and suggests aqueous thin film hydration can be quantified even when the contrast between the film and backing material is low.
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| 44. |
- Nefedova, Irina, et al.
(författare)
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THz spectroscopy techniques for water gradient quantification
- 2022
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 2022-August
-
Konferensbidrag (refereegranskat)abstract
- Understanding depth dependent hydration, or gradients, is important for a wide range of applications from paper manufacturing to biological tissue imaging. However, in situ characterization, especially in a non-destructive, reflective measurement is difficult in practice. Moreover, uncontrolled sample drying, water migration, and surface warping create significant challenges towards experimental testing. In this work we show a simple scenario with a standard cleanroom wipe of around 350μm thickness being exposed to water and left for complete drying, while its reflectivity together with changing mass data were recorded. The reflectivity was measured using VNA-based quasioptical system. High dynamic range, frequency domain measurements show a non-trivial frequency dependence on reflectivity that cannot be explained by aqueous dispersion alone. Further, the measurements reveal complicated drying dynamics where broadband reflectionless behavior was observed even when the sample was still ~50% water by mass. These investigations are an important step towards model model-free based analysis of spectra that should provide direct extraction of water at depth.
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| 45. |
- Pälli, Samu Ville, et al.
(författare)
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Imaging experiments with a 340-GHz FMCW radar and frequency-diverse holograms
- 2023
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - 0277-786X .- 1996-756X. ; 12535
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Konferensbidrag (refereegranskat)abstract
- We present recent developments of a standoff imaging system based on a frequency-diverse phase hologram and deep neural networks. The single-pixel imaging system operates in a monostatic configuration consisting of a 340-GHz FMCW radar and a frequency-diverse phase hologram to interrogate the radar down range direction with spatially varying, frequency-dependent field patterns. The measured back-reflected signal contains spatial reflectivity information from the target, and the fast chirp rate of the radar enables real-time imaging performance. Together with simultaneously acquired visible-light images, a deep neural network integrated into the submillimeter-wave data readout electronics can map the received signal onto a 2D image without mechanical or active electrical beam scanning. In experiments, we have collected submillimeter-wave and visible-light data of a moving target in the region of interest with a 60-Hz frame rate. The results suggest that the system can image the moving target with a resolution comparable to the theoretical diffraction limit. The minimal hardware complexity and good imaging performance of the demonstrated computational submillimeter-wave imaging system support its potential as a cost-effective and easily deployable solution for various imaging applications.
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| 46. |
- Rezapoor, Pouyan, et al.
(författare)
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Cross polarization in swept beam THz imaging systems using off-axis parabolic mirrors
- 2022
-
Ingår i: 2022 16th European Conference on Antennas and Propagation, EuCAP 2022.
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Konferensbidrag (refereegranskat)abstract
- The optical behavior of a terahertz imaging system employing a train of four identical off-axis parabolic mirrors with oblique incidence angle illumination is investigated in this work. The aperture filling and aberrations of a single off-axis parabolic mirror when illuminated by a Gaussian terahertz beam at its focus point is measured and simulated. The amplitude of E-field in transverse electric (TE) and transverse magnetic (TM) polarizations at target plane reveals a significant cross polarization, even when there is zero cross polarization at the source beam, amplitude of which is ∼ 33% of TE polarization. The investigation of the E-field on the detector plane reveals that this ratio is ∼ 1.5% at the detector plane, and the cross polarized E-field at the target plane is rotated back to co polarization. Although its amplitude is negligible, the TM distribution at detector plane is bimodal and tilted about the optical axis.
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| 47. |
- Richter, Heiko, et al.
(författare)
-
Frequency stabilization of 3.5-THz and 4.7-THz quantum-cascade lasers by a phase-locked loop
- 2022
-
Ingår i: 32nd International Symposium of Space Terahertz Technology, ISSTT 2022.
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Konferensbidrag (refereegranskat)abstract
- We report on a phase-locked loop for quantum-cascade lasers operating at 3.5 and 4.7 THz. These frequencies are particularly relevant in atmospheric science and astronomy. The QCLs are locked to the multiplied output of a frequency synthesizer using a Schottky diode harmonic mixer. The resulting linewidths are in the order of a few Hz.
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| 48. |
- Richter, Heiko, et al.
(författare)
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Phase Locking of 3.5-THz and 4.7-THz Quantum-Cascade Lasers Using a Schottky Diode Harmonic Mixer
- 2021
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. ; 46
-
Konferensbidrag (refereegranskat)abstract
- High frequency accuracy and stability are important requirements for local oscillators in terahertz heterodyne spectrometers. We report on a phase-locked loop for quantum-cascade lasers (QCLs) operating at 3.5 and 4.7 THz, two very important frequencies in atmospheric science and astronomy. The QCLs are locked to the multiplied output of a frequency synthesizer using a Schottky diode harmonic mixer.
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| 49. |
- Richter, Heiko, et al.
(författare)
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Phase-Locking of Quantum-Cascade Lasers Operating Around 3.5 THz and 4.7 THz with a Schottky-Diode Harmonic Mixer
- 2024
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 14:3, s. 346-353
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum-cascade lasers (QCLs) are critical components for high-resolution terahertz spectroscopy, especially in heterodyne spectrometers, where they serve as local oscillators. For this purpose, QCLs with stable frequencies and narrow linewidths are essential since their spectral properties limit the spectral resolution. We demonstrate the phase-locking of QCLs around 3.5 THz and 4.7 THz in mechanical cryocoolers. These frequencies are particularly interesting for atmospheric research because they correspond to the hydroxyl radical and the neutral oxygen atom. The phase-locked loop is based on frequency mixing of the QCLs at 3.5 and 4.7 THz with the sixth and eighth harmonic, respectively, generated by an amplifier-multiplier chain operating around 600 GHz, with a Schottky diode harmonic mixer. At both frequencies we achieved a linewidth of the intermediate frequency signal of less than 1 Hz. This is about seven orders of magnitude less than the linewidth of the free running QCL.
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| 50. |
- Shang, Xiaobang, et al.
(författare)
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Interlaboratory investigation of on-wafer S-parameter measurements from 110 GHz to 1.1 THz
- 2023
-
Ingår i: 53rd European Microwave Conference. - 9782874870729 ; , s. 624-627
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an interlaboratory comparison of on-wafer S-parameter measurements of coplanar waveguide (CPW) devices in the frequency range of 110 GHz to 1.1 THz. The comparison was conducted using bespoke calibration standards and verification devices fabricated from high resistivity Silicon. In this study, nine well-established measurement laboratories were involved, and the measurements were performed at different laboratories using different equipment but the same calibration method, i.e. multiline TRL (mTRL). The results show reasonable consistency across a wide frequency range. Observations on the results are provided, along with discussions of factors that may impact interlaboratory reproducibility at such high frequencies.
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