| 1. |
- Alderman, Byron, et al.
(författare)
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A New Pillar Geometry for Heterostructure Barrier Varactor Diodes
- 2001
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Ingår i: 12th International Symposium on Space Terahertz Technology. ; , s. 330-339
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Konferensbidrag (refereegranskat)abstract
- We report on a novel diode geometry, with reduced thermal resistance, for Heterostructure Barrier Varactor, HBV, diodes. The pillar geometry presented here involves the complete removal of the substrate, electrical contacted is made by the forward and reverse side processing of metallic pillars. We propose that there is a limit to the maximum number of barriers that can be used to increase the power capability of a HBV. An analytical model has been developed to study these effects. In considering the case of a perfect thermal heat sink the limit is found to be fourteen, in applying this model to the new pillar structure this is reduced to six.
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| 2. |
- Dillner, Lars, 1968, et al.
(författare)
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Analysis of Symmetric Varactor Frequency Multipliers
- 1997
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Ingår i: Microwave and Optical Technology Letters. ; 15:1, s. 26-29
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Tidskriftsartikel (refereegranskat)abstract
- We investigate efficiency limitations of frequency multipliers with the use of a simple model for symmetric varactors. Our calculations show that the conversion efficiency is improved for a C(V) shape with large nonlinearity at zero volt bias. For quintuplers, the optimal embedding impedance at the third harmonic is an inductance in resonance with the varactor diode capacitance.
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| 3. |
- Dillner, Lars, 1968, et al.
(författare)
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Frequency Multiplier Measurements on Heterostructure Barrier Varactors on a Copper Substrate
- 2000
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 21:5, s. 206-208
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated heterostructure barrier varactors (HBV) on a copper substrate, which offers reduced spreading resistance, and improved thermal conductivity compared to an InP substrate. The devices are fabricated without degrading the electrical characteristics. The three-barrier HBV material grown by MOVPE has a leakage current of only 0.1 mu A/ mu m/sup 2/ at 19 V. The maximum capacitance is 0.54 fF/ mu m/sup 2/. In a frequency tripler experiment a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%.
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| 4. |
- Dillner, Lars, 1968, et al.
(författare)
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Heterostructure Barrier Varactor Multipliers
- 2000
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Ingår i: GAAS 2000. - 0862132223 ; 1, s. 197-200
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Konferensbidrag (refereegranskat)abstract
- The Heterostructure Barrier Varactor (HBV) diode and its application in frequency multipliers is reviewed. Different material systems and HBV models are described. Multiplier performance versus diode parameters and some practical multiplier designs are discussed as well. The best result until now is an efficiency of 12% and an output power of 9 mW at an output frequency of 250 GHz.
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| 5. |
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| 6. |
- Dillner, Lars, 1968
(författare)
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Heterostructure Barrier Varactors for High Efficiency Frequency Multipliers
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the Heterostructure Barrier Varactor (HBV) and its application in frequency multipliers. Different HBV materials, fabrication processes, and device models are presented. The aim of this work is to improve the efficiency of HBV frequency multipliers. Efficiency limitations of symmetric varactor frequency multipliers are investigated. Simple varactor models with capacitance-voltage characteristics of varying shapes have been analyzed. Calculations show that the conversion efficiency is improved for a C(V)-shape with large non-linearity at zero-volt bias. For quintuplers, the optimal embedding impedance at the third harmonic is an inductance in reso-nance with the varactor capacitance. Results are presented from frequency tripler measurements with planar GaAs/AlGaAs HBVs. Simulations and cooled measurements show that self-heating yields excessive conduction current that decreases the efficiency. A new design of planar HBVs has been tested with improved thermal conductance and reduced series resistance. A maximum output power of 4 mW was generated at 246 GHz with an efficiency of 4.8%. A new fabrication process is presented in which HBVs are fabricated on a copper substrate. This process offers reduced parasitic losses and improved thermal conductivity and is carried out without degrading the electrical characteristics. In a frequency tripler experiment, a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%. A quasi-optical HBV tripler is presented. 11.5 mW was generated at 141 GHz with a maximum efficiency of 8%. A non-linear transmission line frequency tripler, consisting of a finline loaded with 15 HBVs, is presented. A maximum output power of 10 mW was generated at 130.5 GHz with an efficiency of 7%, and the 3 dB bandwidth was measured to 10%. A simple design method for the calculation of optimum embedding impedances, maximum efficiency, and pump power for HBV triplers is presented.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Dillner, Lars, 1968, et al.
(författare)
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High Efficiency HBV Multipliers for Millimetre Wave Generation
- 2000
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Ingår i: the XIII International Conference on Microwaves, Radar and Wireless Communications. - 8390666235 ; 3, s. 47-54
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Konferensbidrag (refereegranskat)abstract
- We describe the heterostructure barrier varactor (HBV) diode and its application in frequency multipliers. Different material systems and HBV models are described. In a frequency tripler experiment a maximum output power of 7.1 mW was generated at 221 GHz with a flange-to-flange efficiency of 7.9%.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Fu, Ying, 1964, et al.
(författare)
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AlGaAs/GaAs and InAlAs/InGaAs Heterostructure Barrier Varactors
- 1997
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 82:11, s. 5568-5572
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Tidskriftsartikel (refereegranskat)abstract
- By the Schrödinger and Poisson equations, we have theoretically investigated AlGaAs/GaAs and InAlAs/InGaAs single barrier varactors. The energy band structure, carrier distribution, and conduction current are fully exploited for varactor design. We have explained the experimental current-voltage and capacitance-voltage measurements very well. A simple analytical model for energy band structure is derived based on the Schrödinger and Poisson equation calculation. It is found that a barrier structure of 3 nm Al0.3Ga0.7As/3 nm AlAs/3nm Al0.3Ga0.7As for an Al0.3Ga0.7As/GaAs varactor and a barrier structure of 8 nm In0.52Al0.48As/3 nm AlAs/8 nm In0.52Al0.48As for In0.52Al0.48As/In0.47GaAs are optimal for minimal conduction currents.
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| 15. |
- Fu, Ying, 1964, et al.
(författare)
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Capacitance Analysis for AlGaAs/GaAs and InAlAs/InGaAs Heterostructure Barrier Varactor Diodes
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83:3, s. 1457-1462
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Tidskriftsartikel (refereegranskat)abstract
- By self-consistently solving Schro¨dinger and Poissons equations, we have investigated the capacitances of AlGaAs/GaAs and InAlAs/InGaAs heterostructure barrier varactors. When compared with semiclassical particle model, quantum mechanics show that the maximal capacitance of the varactor is saturated when the spacer and barrier are thin. When the spacer and barrier are very thick, both the quantum mechanics and semiconductor particle approach result in the same conclusion, namely, the maximal capacitance is inversely proportional to the sum of the spacer and barrier thicknesses. We have also shown that the maximal capacitance increases for high carrier effective mass.
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| 16. |
- Fu, Ying, 1964, et al.
(författare)
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Carrier conduction through the quantum barrier in a heterostructure barrier varactor Induced by an AC-Bias
- 2000
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Ingår i: Superlattices and Microstructures. ; 28:2, s. 135-141
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Tidskriftsartikel (refereegranskat)abstract
- By solving the time-dependent Schrodinger equation, we have studied the quantum transport of a wavepacket in a GaAs/A1GaAs heterostructure barrier varactor (HBV) diode induced by an ac bias. The current conduction of a wavepacket is complicated due to the superposition of many different stationary states. When the oscillating frequency of the external bias is relatively low, the motion of the wavepacket follows the electric field induced by the external bias. When the frequency is too high (over 1000 GHz for the GaAs/A1GaAs HBV structure under investigation), the wavepacket becomes effectively confined by the oscillating bias, and the conduction current is significantly reduced.
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| 17. |
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| 18. |
- Hollung, Stein, 1970, et al.
(författare)
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A 141-GHz Integrated Quasi-Optical Slot Antenna Tripler
- 1999
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Ingår i: IEEE Antennas and Propagation Society International Symposium. - 078035639X ; 4, s. 2394-2397
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Konferensbidrag (refereegranskat)abstract
- We present a quasi-optical frequency tripler with heterostructure barrier varactor (HBV) diodes soldered across two slot antennas and located at the focal plane of a dielectric lens. The slot antennas are fed from a WR-22 waveguide connected to a Gunn oscillator. A quasi-optical high-pass filter is used to tune the slot impedance and increase the conversion efficiency. The symmetric capacitance-voltage and asymmetric current-voltage characteristics of the HBV diodes only allows odd harmonics of the applied signal to be generated, and thus simplifies the frequency tripler design.
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| 19. |
- Hollung, Stein, 1970, et al.
(författare)
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A 141-GHz Quasi-Optical HBV Diode Frequency Tripler
- 1999
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Ingår i: Tenth International Symposium on Space Terahertz Technology. ; , s. 492-500
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Konferensbidrag (refereegranskat)abstract
- A 141-GHz quasi-optical heterostructure barrier varactor (HBV) diode frequency tripler is presented. The tripler consists of two slot antennas loaded with FEW diodes and located at the focal plane of a dielectric lens. A quasi-optical high-pass filter is used at the output to improve the conversion efficiency and act as a tuning element for the slot antennas. The tripler demonstrates an effectively isotropic radiated power (EIRP) of 2.24 W at 141 GHz with an input power of 143 mW. The corresponding radiated power is 11.5 mW and the tripler conversion efficiency is about 8%.
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| 20. |
- Hollung, Stein, 1970, et al.
(författare)
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A Distributed Heterostructure Barrier Varactor Frequency Tripler
- 2000
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Ingår i: IEEE Microwave and Guided Wave Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1051-8207. ; 10:1, s. 24-26
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Tidskriftsartikel (refereegranskat)abstract
- We present a broadband nonlinear transmission line (NLTL) frequency multiplier at F-band. The multiplier consists of a finline section periodically loaded with 15 heterostructure barrier varactor (HBV) diodes. Tapered slot antennas are used to couple the fundamental signal from a WR-22 rectangular waveguide to the distributed multiplier as well as radiate the output power into free space. The frequency tripler exhibits 10-dBm peak radiated power at 130.5 GHz with more than 10% 3-dB bandwidth and 7% conversion efficiency. The tripler can be used as an inexpensive broad-band solid-state source for millimeter-wave applications.
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| 21. |
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| 22. |
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| 23. |
- Ingvarson, Mattias, 1974, et al.
(författare)
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Design of Material Structures for Heterostructure Barrier Varactors
- 2001
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Ingår i: 19th Nordic Semiconductor Meeting. ; , s. 68-
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Konferensbidrag (refereegranskat)abstract
- The Heterostructure Barrier Varactor (HBV), first proposed by Kollberg et al. [1], has a symmetric C-V and an anti-symmetric I-V characteristic. Therefore it will only produce odd harmonics of the input frequency when used in mm- and submm-wave frequency multipliers, which greatly simplifies the multiplier design. The high-bandgap barriers prevent electron transport through the structure so that the depletion region of the modulation layers is controlled by the applied bias, thus modulating the capacitance of the device. By varying the number of barriers and the thickness and doping of the modulation layers, it is possible to tailor the HBV diode for various applications, e.g. power-handling capability and frequency of operation.We present four different InGaAs/InAlAs HBV materials on InP fabricated by MOVPE. Two are designed for high-power, mm-wave applications and the other two are optimised for high efficiency up to submm-wave frequencies. In order to handle high power levels, materials 1816 and 1817 have six barriers and a relatively low doping concentration which results in a high break-down voltage. The measured break-down voltage for 1817 of approximately 52 Volts for a current density of 0,1µA/µm2 is, to the best of our knowledge, the highest value reported for HBVs. Materials 1819 and 1820 have higher doping concentrations and shorter modulation layers to reduce losses and the effect of current saturation, see Table 1. Design methods and predicted RF-performance will be presented.
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| 24. |
- Kollberg, Erik, 1937, et al.
(författare)
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Heterostructure Barrier Varactor Multipliers
- 1998
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Ingår i: 2nd ESA Workshop on Millimetre Wave Technology and Applications. ; , s. 429-434
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Konferensbidrag (refereegranskat)abstract
- We describe the Heterostructure Barrier Varactor (HBV) diode and its application in frequency multipliers. Different varactor models are presented that easily can be used in large signal simulations. Results from frequency multiplier measurements are presented. The delivered maximum output power at 234 GHz is 3.6 mW. Simulations show that the output power is limited by excessive conduction current due to increased diode temperature.
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| 25. |
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| 26. |
- Mahiey, S, et al.
(författare)
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A Broadband Frequency Tripler for SIS Receivers
- 1998
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Ingår i: Ninth International Symposium on Space Terahertz Technology. ; , s. 481-491
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Konferensbidrag (refereegranskat)abstract
- Considerable success has recently been gained in the design and production of high powered frequency triplers incorporating Schottky varactor diodes. The design approach that was used for this goal has now been turned to the design of fixed tuned, broadband frequency triplers specifically intented for use in SIS receivers.The tripler reported here makes the use of a Heterostructure Barrier Varactor or HBV. A waveguide circuit has been designed that provides more than 50µW of output power for an input power of 10mW over a frequency range of 250 - 300GHz completely fixed tuned and without the need for bias.Further modification of the waveguide circuit should extend the useful fixed tuned bandwidth to greater than 100GHz centered at 300GHz.
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| 27. |
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| 28. |
- Stake, Jan, 1971, et al.
(författare)
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Analysis of Carrier Transport in a Heterostructure Barrier Varactor Diode Tripler
- 1997
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Ingår i: International Semiconductor Device Research Symposium (ISDRS). ; , s. 183-186
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Konferensbidrag (refereegranskat)abstract
- We report the time evolution and the spatial variation of the conduction band, the electric field, and the carrier density for a GaAs/Al0.7GaAs Heterostructure Barrier Varactor diode operating in a 3x90 GHz frequency tripler. The third harmonic output power and optimal embedding impedances are given for two different diodes at pump powers of 50 mW and 100 mW.
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| 29. |
- Stake, Jan, 1971, et al.
(författare)
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Design of 100-900 GHz AlGaAs/GaAs Planar Heterostructure Barrier Varactor Frequency Triplers
- 1998
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Ingår i: Ninth International Symposium on Space Terahertz Technology. ; , s. 359-366
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Konferensbidrag (refereegranskat)abstract
- In this paper we offer a simple set of accurate frequency-domain design equations that can be used to calculate optimal embedding impedances and tripling efficiency. These equations can be used for a wide range of device and circuit parameters. The effects of parasitic resistance and operating temperature on device performance, and how these parameters vary with device design are explored. Comparisons to experiment are made for planar HBVs demonstrating at least 3 % efficiency at 78 GHz input frequency and 50 mW of input power.
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| 30. |
- Stake, Jan, 1971, et al.
(författare)
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Effects of Self-Heating on Planar Heterostructure Barrier Varactor Diodes
- 1998
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Ingår i: IEEE Transactions on Electron Devices. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9383. ; 45:11, s. 2298-2303
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Tidskriftsartikel (refereegranskat)abstract
- The conversion efficiency for planar Al0.7GaAs-GaAs heterostructure barrier varactor triplers is shown to be reduced from a theoretical efficiency of 10% to 3% due to self-heating. The reduction is in accordance with measurements on planar Al0.7GaAs-GaAs heterostructure barrier varactor (HBV) triplers to 261 GHz at room temperature and with low temperature tripler measurements to 255 GHz. The delivered maximum output power at 261 GHz is 2.0 mW. Future HBV designs should carefully consider and reduce the device thermal resistance and parasitic series resistance. Optimization of the RF circuit for a 10 ?m diameter device yielded a delivered output power of 3.6 mW (2.5% conversion efficiency) at 234 GHz
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| 31. |
- Stake, Jan, 1971, et al.
(författare)
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Fabrication and Characterisation of Heterostructure Barrier Varactor Diodes
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report deals with fabrication and characterisation of Heterostructure Barrier Varactor (HBV) diodes for frequency multiplier applications. The process steps involved are clean-ing, device isolation, passivation, ohmic contacts, thick metal, air-bridge formation, transfer of EPI-layers to copper substrate, and formation of mechanical support for the whisker. These fabrication steps are described in detail.The characterisation techniques of HBVs are described in detail. An equivalent circuit is extracted from on-wafer S-parameter measurements (0,045-50 GHz). In combination with DC-measurements (ohmic contact resistance, I-V characteristic) a large-signal model for frequencies up to the submillimetre wavelength can be extracted. Furthermore, the relative error in extracted varactor parameters from high frequency S-parameter measurements is presented.The results of lattice matched and pseudomorphic GaAs/AlGaAs, InGaAs/InAlAs, InAs/AlSb and phosphide containing materials for HBVs are presented. The best material for millimetre and submillimetre wave HBVs, among those tested, is the In0,53Ga0,47As/In0,52Al0,48As system with a thin AlAs layer (30 Å) in the middle of the barrier.
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| 32. |
- Stake, Jan, 1971, et al.
(författare)
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Heterostructure-Barrier-Varactor Design
- 2000
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9480 .- 1557-9670. ; 48:4, s. 677-682
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a simple set of accurate frequency-domain design equations for calculation of optimum embedding impedances, optimum input power, bandwidth, and conversion efficiency of heterostructure-barrier-varactor (HBV) frequency triplers. A set of modeling equations for harmonic balance simulations of HBV multipliers are also given. A 141-GHz quasi-optical HBV tripler was designed using the method and experimental results show good agreement with the predicted results.
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| 33. |
- Stake, Jan, 1971, et al.
(författare)
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Improved Diode Geometry for Planar Heterostructure Barrier Varactors
- 1999
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Ingår i: Tenth International Symposium on Space Terahertz Technology. ; , s. 485-491
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Konferensbidrag (refereegranskat)abstract
- We report state-of-the-art performance of tripler efficiency and output power for a new design of AlGaAs-based heterostructure barrier varactor diodes. The new diodes were designed for reduced thermal resistance and series resistance. An efficiency of 4.8% and a maximum output power of 4 mW was achieved at an output frequency of 246 GHz.
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| 34. |
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| 35. |
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| 36. |
- Strupinski, W., et al.
(författare)
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MOVPE strain layers - growth and application
- 2000
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Ingår i: Journal of Crystal Growth. ; 221, s. 20-25
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Tidskriftsartikel (refereegranskat)abstract
- The critical thickness, characteristic for the lattice-mismatch parameter, plays a key role in the growth of strain layers. The driving force for the 2D-3D transition can be minimized by slowing the relaxation of misfit strain. As a result the relatively smooth layer is deposited at lower temperature for the optimal growth rate. The quality of the InGaAs- and AlAs-strained layers deposited on InP substrate have been examined by the XRD, AFM and SIMS methods. Atomic force microscopy allows to observe 3D growth mode even for very thin layers. Relatively strong relaxation effects are recognized by surface roughness. Two-dimensional di!raction measurement is a much more sensitive tool for the estimation of relaxation degree. The observations results were applied in the heterostructure barrier varactor (HBV) diode. In order to minimize the conduction current through HBV two materials with different design of the barriers were studied: one heterostructure with three homogeneous lattice matched barriers consisting of 20nm Al0.48In0.52As and another one with strained step-like barriers consisting of 5 nm Al0.48In0.52As, 3 nm AlAs and 5 nm Al0.48In0.52As. We found that the use of strained step-like barriers results in a much lower conduction current. For current density
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