| 1. |
- Ducournau, G., et al.
(författare)
-
200 GHz communication system using unipolar InAs THz rectifiers
- 2013
-
Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467347174
-
Konferensbidrag (refereegranskat)abstract
- We report on the first use of a THz detector based on InAs rectifying nanochannels in a communication system. The transmitter is composed of an electronic multiplication chain, externally amplitude modulated at the input signal. The system has been driven at 200 GHz and up to 500 Mbps data signals have been transmitted in an indoor configuration. In contrast to most nanodevices, the InAs detector has a low impedance (580 ω) and is therefore easily loaded by 50 ω electronics. The data rate limitation is mainly coming from parasitics coupled in the board. © 2013 IEEE.
|
|
| 2. |
- García-Pérez, Ó, et al.
(författare)
-
Experimental analysis of shot-noise suppression in InGaAs/InAlAs recessed planar diodes at room temperature
- 2015
-
Ingår i: 2015 International Conference on Noise and Fluctuations, ICNF 2015. - 9781467383356
-
Konferensbidrag (refereegranskat)abstract
- In this work, current noise measurements of submicron InGaAs/InAlAs recessed planar diodes are presented. The presence of a barrier in the potential profile under the source side of the recess may affect the statistics of passage of carriers, which in turn would lead to suppressed shot noise levels. However, evidencing this noise suppression from the measurements is challenging, due to the undesired effects from the accesses and contact resistances. The presented results are provided as a starting point for a future de-embedding process able to precisely determine the actual noise properties below the recess.
|
|
| 3. |
- García-Pérez, Ó, et al.
(författare)
-
Shot-noise suppression effects in InGaAs planar diodes at room temperature
- 2015
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 647:1
-
Konferensbidrag (refereegranskat)abstract
- In this work, the noise characteristics of InGaAs planar diodes are studied. The presence of a recessed region originates a barrier in the potential profile, which can modulate the passage of ballistic carriers along the structure. This effect, in turn, may lead to suppressed levels of noise with respect to the full Poissonian value due to Coulomb interaction. With the aim of evidencing such phenomenon, the noise properties of a set of devices with different dimensions have been measured at room temperature. Some evidence of potential shot-noise suppression is observed in the results, but the undesired effect of resistive contacts and accesses has been found to be a limiting factor to quantify the suppression accurately.
|
|
| 4. |
- L.Q.Zhang,, et al.
(författare)
-
Fabrication of novel unipolar nanodiodes in InAs/AlSb for microwave detection
- 2011
-
Ingår i: Infrared, Millimeter and Terahertz Waves (IRMMW-THz), 2011 36th International Conference on. - 2162-2027. - 9781457705083 ; :2-7 Oct. 2011, s. 1-2
-
Konferensbidrag (refereegranskat)abstract
- Abstract—We report on the fabrication of unipolar nanodiodes into an InAs/AlxGa1-xSb quantum-well heterostructure for room temperature microwave detection up to 110 GHz. Electron-beam lithography was combined with both dry- and wet-etching, and we explored the differences in the electric and detection parameters with the two methods.
|
|
| 5. |
- Mateos, J., et al.
(författare)
-
Room temperature THz detection and emission with semiconductor nanodevices
- 2013
-
Ingår i: Proceedings of the 2013 Spanish Conference on Electron Devices, CDE 2013. - 9781467346689 ; , s. 215-218
-
Konferensbidrag (refereegranskat)abstract
- In this paper we present the advances on the fabrication of THz emitters and detectors obtained within the framework of the European ROOTHz project. Two types of devices are explored, self-switching diodes and slot-diodes, using both narrow bandgap and wide bandgap semiconductors. This broad approach allows us to improve the frequency and power generated by Gunn diodes and the responsivity and noise of detectors at THz frequencies.
|
|
| 6. |
- Rodriguez-Fernandez, A., et al.
(författare)
-
Temperature and Surface Traps Influence on the THz Emission from InGaAs Diodes
- 2015
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 647:1
-
Konferensbidrag (refereegranskat)abstract
- Monte Carlo simulations forecast Gunn-like oscillations at ∼0.75-1.25 THz in InGaAs planar recessed diodes (slot diodes); however, up to date no experimental evidence of this effect has been observed. The effects of temperature and surface charges on the emission parameters from InGaAs diodes are analyzed by means of an ensemble Monte Carlo simulator. Cooling the device down to 77 K strongly improves the amplitude of the oscillations and can increase their frequency. On the other hand, the ratio between cap and recess charges plays an important role for the onset of oscillations. A high level of traps in the recess region may completely attenuate the emission.
|
|
| 7. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Cryogenic DC Characterization of InAs/Al80Ga20Sb Self-Switching Diodes
- 2013
-
Ingår i: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - 1092-8669. - 9781467361316
-
Konferensbidrag (refereegranskat)abstract
- DC characterization of an InAs/Al80Ga20Sb self-switching diode for THz detection is presented at 300 K and 6 K. Compared to 300 K, an enhancement of the diode I-V nonlinearity and associated responsivity was observed under zero-bias conditions at 6 K. The intrinsic responsivity was estimated to 490 V/W at 300 K and 4400 V/W at 6 K.
|
|
| 8. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Fabrication and DC characterization of InAs/AlSb self-switching diodes
- 2012
-
Ingår i: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - 1092-8669. - 9781467317252 ; , s. 65-68
-
Konferensbidrag (refereegranskat)abstract
- Fabrication and DC measurements of an InAs/AlSb self-switching diode (SSD), aimed for THz detection, is presented. An SSD with a channel width of 160 nm and a trench width of 240 nm was designed and fabricated in a process using an in situ passivation procedure of the oxidation-sensitive trench. Rectifying behavior was observed in the I-V characteristics. The device performance was relatively stable over a period of three months.
|
|
| 9. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Graphene self-switching diodes as zero-bias microwave detectors
- 2015
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 106:9, s. 093116-
-
Tidskriftsartikel (refereegranskat)abstract
- Self-switching diodes (SSDs) were fabricated on as-grown and hydrogen-intercalated epitaxial graphene on SiC. The SSDs were characterized as zero-bias detectors with on-wafer measurements from 1 to 67 GHz. The lowest noise-equivalent power (NEP) was observed in SSDs on the hydrogen-intercalated sample, where a flat NEP of 2.2 nW/Hz½ and responsivity of 3.9 V/W were measured across the band. The measured NEP demonstrates the potential of graphene SSDs as zero-bias microwave detectors.
|
|
| 10. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Nanochannel diodes based on InAs/Al80Ga20Sb heterostructures: Fabrication and zero-bias detector properties
- 2015
-
Ingår i: Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics. - : American Vacuum Society. - 2166-2746 .- 2166-2754. ; 33:2, s. 021207-
-
Tidskriftsartikel (refereegranskat)abstract
- The authors present a novel process for fabrication of deep submicron isolation patterns in InAs/Al80Ga20Sb heterostructures. The process is demonstrated by processing InAs/Al80Ga20Sb self-switching diodes (SSDs). SSDs require high-resolution isolation patterns, which presents a major fabrication challenge because of the oxidation sensitivity of Al(Ga)Sb alloys. The presented fabrication process completely avoided exposure of Al(Ga)Sb to air and resulted in an isolation pattern with a feature size down to 35 nm. The process was based on a dry etch of isolating trenches, in situ removal of the resist etch mask followed by in situ encapsulation of etched surfaces by silicon nitride. The applicability of the InAs/Al80Ga20Sb SSD process was demonstrated with on-wafer RF measurements of zero-bias detection up to 315 GHz. Below 50 GHz, the detector's noise equivalent power was estimated to less than 100 pW/Hz½ .
|
|
| 11. |
- Westlund, Andreas, 1985
(författare)
-
Novel Terahertz Emitters and Detectors: InGaAs Slot Diodes and InAs Self-Switching Diodes
- 2013
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two novel types of diodes for emission and detection of THz radiation have been investigated. The diodes are based on high electron mobility III-V heterostructures. Both diodes are aimed for room-temperature operation, for which there is a demand for new THz technology. For emission, slot diodes based on an InGaAs heterostructure were studied. Slot diodes have been proposed as a potential power source at terahertz frequencies. However, slot diodes have never been demonstrated experimentally, only in Monte Carlo (MC) simulations. In this thesis, design, fabrication and I-V characterization of slot diodes are covered, as well as emission experiments. Despite the fact that MC simulations predicted an output power of 50 µW at 0.8 THz or higher, no emission was detected for the fabricated slot diodes experimentally up to 1 THz with a noise floor of 10 nW.For detection, InAs self-switching diodes (SSDs) for zero-bias operation were investigated. Fabrication, design and characterization of InAs SSDs are presented. Responsivity was measured on-wafer in the range 2-315 GHz, for which no roll-off was observed. At 50 GHz, the InAs SSD showed a responsivity of 17 V/W and noise-equivalent power (NEP) of 150 pW/Hz½ when driven by a 50 Ω source. With a conjugately matched source a responsivity of 34 V/W and NEP of 65 pW/Hz½ are expected, based on s-parameters and responsivity as measured with a 50 Ω source. An InAs SSD designed with a substrate antenna demonstrated detection in a free-space experiment at 600 GHz. For comparison, InGaAs SSDs which are a more established type of SSDs were evaluated. For InGaAs SSDs, a lowest NEP of 65 pW/Hz½ with a 50 Ω source was achieved, measured at 50 GHz. The measured responsivity was 280 V/W. It was observed that DC measurements can be used to successfully predict responsivity and NEP of SSDs. Also, the first systematic experimental study of how the design influences the SSD detection performance was carried out.
|
|
| 12. |
- Westlund, Andreas, 1985, et al.
(författare)
-
On the effect of delta-doping in self-switching diodes
- 2014
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:9, s. Article Number: 093505 -
-
Tidskriftsartikel (refereegranskat)abstract
- Lowering the carrier concentration is presented as a way to considerably improve the performance of self-switching diode (SSD) detectors. A physics-based theoretical model was used to derive an expression for the responsivity of SSDs as a function of carrier concentration, mobility, and design parameters. Monte Carlo simulations confirmed the modeled effect of varying carrier concentration and channel width. SSDs were fabricated in InAs heterostructures with different delta-doping levels. Radio frequency (RF) characterization at 50 GHz reproduced the modeled trends. By reducing the carrier concentration in InAs SSDs with 40 nm wide channels from 2.7 x 10(12) cm(-2) to 1.5 x 10(12) cm(-2) (-44%), the noise equivalent power (NEP) improved from 130 pW/Hz(1/2) to 87 pW/Hz(1/2) (-33%).
|
|
| 13. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Optimization and small-signal modeling of zero-bias InAs self-switching diode detectors
- 2015
-
Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101. ; 104:Feb, s. 79-85
-
Tidskriftsartikel (refereegranskat)abstract
- Design optimization of the InAs self-switching diode (SSD) intended for direct zero-bias THz detection is presented. The SSD, which consists of nanometer-sized channels in parallel, was described using an equivalent small-signal circuit. Expressions for voltage responsivity and noise equivalent power (NEP) were derived in terms of geometrical design parameters of the SSD, i.e. the channel length and the number of channels. Modeled design dependencies were confirmed by RF and DC measurements on InAs SSDs. In terms of NEP, an optimum number of channels were found with the detector driven by a 50 Omega source. With a matched source, the model predicted a responsivity of 1900 V/W and NEP of 7.7 pW/Hz(1/2) for a single-channel InAs SSD with 35 nm channel width. Monte Carlo device simulations supported observed design dependencies. The proposed small-signal model can be used to optimize SSDs of any material system for low-noise and high-frequency operation as zero-bias detectors. In large signal measurements, the responsivity of the InAs SSDs exhibited a 1 dB deviation from linear responsivity at an input power of -3 dBm from a 50 Omega source.
|
|
| 14. |
- Westlund, Andreas, 1985
(författare)
-
Self-Switching Diodes for Zero-Bias Terahertz Detection
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The self-switching diode (SSD) has been investigated as a potential terahertz detector in recent years. The SSD accomplishes a non-linear current-voltage relation through a field-effect, which enables detection at zero bias from microwave up to terahertz frequencies. In this work, SSDs were realised in two new materials; InAs and graphene. InGaAs SSDs were also fabricated. The effect of geometrical and material parameters on SSD detector performance under zero bias were for the first time described by an analytical model, and confirmed by experiment. InAs SSDs were fabricated in an InAs/AlSb heterostructure. A noise equivalent power (NEP) of 150-200 pW/Hz½ was observed at 2-315 GHz with a 50 Ω source. InGaAs SSDs fabricated in an InGaAs/InAlAs heterostructure exhibited an NEP of 40-150 pW/Hz½ at 2-315 GHz with a 50 Ω source, the lowest NEP reported for any SSD in this frequency range. An InAs SSD integrated with a spiral antenna and silicon lens demonstrated an NEP of less than 4.4 nW/Hz½ at 600 GHz.SSDs require a deep submicron isolation pattern which presents a major fabrication challenge in the InAs/AlSb heterostructure due to the oxidation sensitivity of the thick AlSb buffer layer. An SSD process was developed that allowed the fabrication of InAs/AlSb isolation patterns with feature sizes down to 35 nm. Graphene SSDs were demonstrated for the first time. The SSD was based on epitaxial graphene on silicon carbide. A flat NEP of 2.4 nW/Hz½ was measured from 1 to 67 GHz using a 50 Ω source. An analytical model of the SSD was derived to explain the influence of geometrical and material parameters. The model predicted that lowering the two-dimensional electron gas carrier concentration in the heterostructure increased the responsivity and reduced the NEP of the SSD zero-bias detector. Device simulations and measurements confirmed the predictions. Further, the model, together with experiments, showed that to minimize NEP there is an optimum number of channels and optimal channel length. The frequency dependence of SSD detectors was described using a small-signal equivalent circuit, which reproduced the measured responsivity up to 315 GHz. The highest cut-off frequency of InAs SSDs was estimated to 775 GHz.
|
|
| 15. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Terahertz detection in zero-bias InAs self-switching diodes at room temperature
- 2013
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:13
-
Tidskriftsartikel (refereegranskat)abstract
- RF characterization of InAs self-switching diodes (SSDs) is reported. On-wafer measurements revealed no roll-off in responsivity in the range of 2-315 GHz. At 50 GHz, a responsivity of 17 V/W and a noise-equivalent power (NEP) of 150 pW/Hz(1/2) was observed for the SSD when driven by a 50 Omega source. With a conjugately matched source, a responsivity of 34 V/W and an NEP of 65 pW/Hz(1/2) were estimated. An antenna-coupled SSD demonstrated a responsivity of 0.7 V/W at 600 GHz. The results demonstrate the feasibility of zero-bias terahertz detection with high-electron mobility InAs SSDs up to and beyond 100 GHz.
|
|
| 16. |
- Westlund, Andreas, 1985, et al.
(författare)
-
Zero-Bias Self-Switching In65Ga35As channel Diodes for Terahertz Detection
- 2015
-
Ingår i: IEEE International Conference on Indium Phosphide and Related Materials Conference Proceedings 2015. ; CSW 2015, s. 82-83
-
Konferensbidrag (refereegranskat)abstract
- An alternative to the transistor for high-frequency detector applications is the two-terminal self-switching diode (SSD). The SSD is based on a nanometer-wide channels and a lateral gate connected to a drain. SSDs with In65Ga35As channels were fabricated and characterized. The design was optimized for low noise detection. In on-wafer measurements 2-315 GHz, a responsivity >150 V/W and noise-equivalent power (NEP) 50-100 pW/Hz½ was measured with a 50 Ω source. In the measured frequency range, this is the lowest NEP for SSDs demonstrated.
|
|
