| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
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| 5. |
- 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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| 6. |
- 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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| 7. |
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| 8. |
- 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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| 9. |
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| 10. |
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| 11. |
- 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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| 12. |
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| 13. |
- 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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