High efficiency pulsed GaAs Read impatt diodes

GaAs Read impatt diodes have been developed for pulsed operation in X and Ku bands. Conversion efficiencies of 32% and 29% have been measured for p+n+n?n+ (high-low) doping profiles grown by liquid phase and vapour phase epitaxy, respectively. Peak powers of 30 W in X band and 20 W in Ku band have been obtained with single mesas on gold plated heatsinks. Multiple mesas in parallel and diamond heatsinking were employed to improve thermal resistance. Microwave circuit and chip level power combining techniques were also investigated and greater than 90% combining efficiency was achieved on the chip level.     

Observed behaviour of high-efficiency impatt diodes over a 30% frequency range

High-power high-efficiency oscillator operation of hi-lo-doped GaAs impatt diodes has been obtained over a frequency range extending from 7.5 to 12 GHz. Arrays of diodes have been used to obtain up to 7.7 W at 22% efficiency. From the measured variation of output power with load resistance, it is concluded that these diodes are operating in the premature collection mode.     

Effect of Temperature on Device Admittance of GaAs and Si IMPATT Diodes

The effect of temperature on the small-signal admittance of IMPATT diodes with uniformly doped and high-low doped (Read) structures is investigated experimentafly and theoretically. Small-signal admittance characteristics of X-band Si p+-n-n+, GaAs M-n-n+ (Schottky-uniform), and GaAs M-n+-n-n+ (Schottky-Read) IMPATT diodes are measured at various junction temperatures for different dc current levels. Small-signal analysis is performed on GaAs IMPATT diodes of uniformly doped and high-low doped structures, and the calculated results on temperature dependence of the device admittance are compared with the experimental results. Reasonable agreement is found between theory and experiment. It is shown that GaAs IMPATT diodes are superior to Si diodes in admittance temperature characteristics and that the uniformly doped structure has a small admittance temperature coefficient in magnitude, compared to the high-low doped structure. It is also shown by calculation that the admittance temperature coefficient of a punch-through diode is small in magnitude, compared to that of a non-punch-through diode.     

Improved performance of millimetre-wave impatt diodes on type-IIa diamond heatsinks

Thermal resistance and r.f. data are presented for Ka?-, V and W-band silicon double-drift impatt diodes employing diamond heatsinks. A power level of 620 mW at 7.7% efficiency has been achieved at 101 GHz.     

Ion-implanted p?n junction indium-phosphide impatt diodes

Implantation of beryllium ions into a uniformly doped n-type InP epitaxial layer grown by vapour-phase epitaxy has been utilised to create a p+?n junction for flat-profile single-drift impatt diodes. An r.f. performance comparable to gallium arsenide has been obtained. A c.w. output power of 1.6 W with 11.1% conversion efficiency has been measured at 9.78 GHz and a peak power of 6.1 W with 13.7% efficiency has been measured at 10.8 GHz with 10% duty cycle. The f.m. noise of the c.w. oscillators is comparable to results reported for silicon.     

Modeling the effect of deep traps on the capacitance–voltage characteristics of p-type Si-doped GaAs Schottky diodes grown on high index GaAs substrates

Numerical simulation, using SILVACO-TCAD, is carried out to explain experimentally observed effects of different types of deep levels on the capacitance–voltage characteristics of p-type Si-doped GaAs Schottky diodes grown on high index GaAs substrates. Two diodes were grown on (311)A and (211)A oriented GaAs substrates using Molecular Beam Epitaxy (MBE). Although, deep levels were observed in both structures, the measured capacitance–voltage characteristics show a negative differential capacitance (NDC) for the (311)A diodes, while the (211)A devices display a usual behaviour. The NDC is related to the nature and spatial distribution of the deep levels, which are characterized by the Deep Level Transient Spectroscopy (DLTS) technique. In the (311)A structure only majority deep levels (hole traps) were observed while both majority and minority deep levels were present in the (211)A diodes. The simulation, which calculates the capacitance–voltage characteristics in the absence and presence of different types of deep levels, agrees well with the experimentally observed behaviour.     

Amplification with 3-terminal avalanche devices

The letter investigates the influence of a thermionic-type injected current on the dynamic operating conditions and performance of GaAs impatt diodes. For this study, the computer program developed for high-efficiency impatt diodes has been used extensively. The work shows that interesting results can be obtained in X-band and that the practical realisation of such a device would be possible by using a transistor in which the transistor effect, avalanche effect and transit-time effect are used in combination.     

Computer studies on the widening of the avalanche zone and the decrease in efficiency of silicon X-band symmetrical double-drift impatt diodes at high current densities

A computer study of the field and current profiles of silicon X-band symmetrical d.d.r. impatt diodes is presented. The results show that there is considerable widening of the avalanche zone at high values of current density. This causes a sharp fall in the efficiency of the device at high current density after reaching a maximum.     

Fundamental high-frequency performance limit for impatt mode operation

It is well known that the phase delay associated with carrier energy relaxation in impatt diodes tends to improve their performance. The purpose of the letter is to point out that there is also an amplitude degradation effect which tends to impair impatt performance. At high enough frequencies the amplitude degradation effect dominates, leading to a high-frequency performance roll-off. The net effect of energy relaxation is believed to be deleterious for frequencies above about 500 GHz for Si devices, and at lower frequencies for GaAs devices.     

Common-gate GaAs f.e.t. oscillator

Frequency tuning, power and noise characteristics of a common-gate GaAs f.e.t. oscillator were investigated. By changing the common-gate lead inductance, the frequency was changed by almost two octaves. The f.m. noise of the low-Q factor f.e.t. oscillator was at the same level as that of a medium-Q factor GaAs impatt oscillator.     

Hybrid rectenna and monolithic integrated zero-bias microwave rectifier

In this study, we have developed a hybrid sensitive rectenna (rectifier + antenna) system at 2.45 GHz. To achieve this system, we have first optimized and validated a zero-bias microwave sensitive rectifier using commercial Schottky diodes. We have then optimized and achieved a 2/spl times/2 patch antenna array, which is associated to the microwave rectifier in order to validate the rectenna system, where an RF-dc conversion efficiency of 56% has been observed experimentally. In order to minimize the rectenna dimensions, we have conducted a study using the OMMIC ED02AH 0.20-/spl mu/m GaAs pseudomorphic high electron-mobility transistor process to develop and achieve a monolithic rectifier at 2.45 GHz with RF-dc conversion efficiency of 65%.     

Design considerations of low-noise high-efficiency silicon IMPATT diodes

The noise and efficiency of p⁺-n1-n2-n⁺and n⁺-p1- p2-p⁺high-low silicon IMPATT diodes have been studied as a function of doping ratio n1/n2or p1/p2. In contrast to GaAs IMPATT diodes whose efficiency can be improved with some degradation of noise performance, both the efficiency and noise of Si IMPATT diodes can be improved. As an example, for a 6-GHz silicon n⁺-p1-p2-p⁺IMPATT structure with a doping ratio of 10, the efficiency is 21 percent and the incremental noise as compared to a uniformly doped structure is about -6 dB. These results indicate that silicon high-low structures can compete favorably with GaAs structures in both efficiency and noise performances.     

Ideality and noise figure characteristics of r.f. sputtered millimetre GaAs diodes

Refractory Schottky barriers have been incorporated in millimetre GaAs mixer diodes to improve r.f. performance and burnout resistance. It is shown that low power r.f. sputter deposition of TiW and Ti-Mo refractories results in degradation of noise temperature ratio and to a first approximation does not affect d.c. parameters, especially the ideality factor.     

Frequency increase in pulsed avalanche diodes

We have tested many GaAs IMPATT diodes under high power pulsed conditions and found that the best power output and efficiency occur at higher frequencies in the pulsed mode than in the CW mode. This phenomenon can be understood by considering the effect on the avalanche region field produced by the space charge of the carriers injected into the drift zone. Qualitative agreement is demonstrated between theory and experiment.     

Reduction of FM noise in impatt oscillators by optical illumination

Experiments are described in which laser illumination of the active device has reduced the FM noise output by up to 5 dB for a GaAs impatt oscillator and 2 dB for a Si impatt oscillator. A qualitative explanation of the observed results is given, and the effect of laser amplitude noise on the maximum noise reduction obtainable is shown.     

The effects of trap-induced lifetime variations on the design andperformance of high-efficiency GaAs solar cells

The authors investigate the impact of Shockley-Read-Hall (SRH) lifetime behavior directly on GaAs solar cell performance and design optimization for various lifetime-limiting defects, characterized by trap position, cross section, and trap density. It is demonstrated theoretically and experimentally, for a specific cell design, how far GaAs cell efficiency can be from the optimum efficiency if certain types of bulk defects limit the lifetime and are not properly accounted for. A realistic situation is considered where cell designers/manufacturers know the bulk lifetime at some nominal carrier concentrations but are unaware of the trap characteristics or defect responsible for this lifetime. An improved GaAs p/n heteroface cell design is proposed. This design utilizes a high-low junction and a thin base, with AlGaAs back-surface passivation     

140 GHz 70 mW CW output power with n-type silicon single-drift impatt diodes

Silicon single-drift-region impatt diodes designed to operate at D-band frequencies were fabricated with a p+ nn+ structure formed by thermal diffusion of boron. A continuous-wave output power of 70 mW at 137 GHz with a conversion efficiency of 3.2% was obtained. The diodes were packaged with a quartz standoff configuration on a copper heatsink and mounted into a cap-type waveguide resonator.     

Simulation of non steady-state transport in GaAs and InP millimeter Impatt diodes

Large-signal simulations of non-stationary transport in GaAs and InP millimeter Impatt diodes have been performed. This study of the influence of non steady-state features on the performance of a 100 GHz operation shows that non punch-through structures still present interesting performances at this frequency. However, for this type of structure, InP exhibits significant advantages over GaAs for the manufacture of high efficiency diodes.     

高效率砷化镓崩越二极管的并联组合

本文叙述了高效率砷化镓崩越二极管的并联组合技术及多管芯并联器件的热设计;简单介绍了并联器件制造工艺;并给出了两管芯并联的实验结果:在X波段最大输出功率为5.4W,最佳效率达26.6%.     

Potentials of GaP as millimeter wave IMPATT diode with reference to Si, GaAs and GaN

This paper presents the simulation results of DC,small-signal and noise properties of GaP based Double Drift Region( DDR) Impact Avalanche Transit Time( IMPATT) diodes. In simulation study we have considered the flat DDR structures of IMPATT diode based on GaP,GaAs,Si and GaN( wurtzite,wz) material. The diodes are designed to operate at the millimeter window frequencies of 94 GHz and 220 GHz. The simulation results of these diodes reveal GaP is a promising material for IMPATT applications based on DDR structure with high break down voltage( V_B) as compared to Si and GaAs IMPATTs. It is also encouraging to worth note GaP base IMPATT diode shows a better output power density of 4. 9 × 10~9 W/m~2 as compared to Si and GaAs based IMPATT diode. But IMPATT diode based on GaN( wz) displays large values of break down voltage,efficiency and power density as compared to Si,GaAs and GaP IMPATTs.