GaAs IMPATT Diodes Research Articles

Second Harmonic Power Generation from GaAs-Impatt Diodes at 210 GHz

Investigations of GaAs-IMPATT diodes as self-pumped frequency doublers are carried out both, theoretically and experimentally. Optimization criterions are specified and first experimental results are presented. 1 mW output power has been achieved in the harmonic mode at 210 GHz.

Large Signal Model of an Optically Controlled GaAs IMPATT Diode

A large signal model of an optically controlled Read-type GaAs IMP ATT diode has been presented. In contrast to other existing theories, we consider the effect of photogenerated carriers in the avalanche zone which significantly affects the device characteristics in the illuminated condition. The model presented here is used to examine the effect of illumination on the output power, efficiency and negative conductance of the device. It has been found that for constant bias current, the output power and efficiency of the device are strong functions of the incident optical power. The model can be used as a basic tool for optimising GaAs IMPATT diodes for optically controlled applications in microwave region.

Computer studies of quasi Read gallium arsenide IMPATT diode: including the effect of space charge

Computer studies have been carried out on the effects of variation of impurity hump parameters of quasi Read high–low (hi–lo) and low–high–low (lo-hi–lo) gallum arsenide IMPATT diodes on their DC and microwave properties. The effect of mobile space charge has been included in the computer analysis. It turns out that the DC properties of the diode are sensitive functions of the width and doping concentration of impurity bumps. The optimum efficiency is found to be respectively 24.5% and 27.9% for hi–lo and lo-hi–lo diodes designed for 18 GHz frequency. The small signal admittance calculations show that a lo-hi–lo structure provides higher negative conductance and better quality factor compared with a hi–lo structure of GaAs Impatt diode.

A resonant-cap power combiner for two-terminal millimeter-wave devices

A power combiner for three active two-terminal devices located under a common resonant cap is presented. An equivalent circuit with lumped elements describing the coupling between the devices is derived from a numerical finite-element simulation of the resonator. The applied monolithically integrated mounting technique for the active devices minimizes parasitic elements and gains high reproducibility and symmetry. Experimental results with GaAs IMPATT diodes on diamond heatsink of up to 500 mW at 91 GHz with a dc to RF conversion efficiency of 9.0% and excellent combining efficiency demonstrate the capability for power generation in the mm-wave region.

New mounting technique for two-terminalmillimetre-wave devices

A new mounting technique for two-terminal devices is presented which minimises parasitic elements and improves thermal heat resistance. Monolithic fabrication of the structure leads to high reproducibility. First experimental results for power generation at W-band frequencies with GaAs Impatt diodes are reported. >

A comparative study on the noise measure of millimetre-wave GaAs impatt diodes

It is theoretically and experimentally demonstrated that the small-signal noise measure of Gaas single-drift Impatt-diodes can efficiently be reduced by increasing the total width of the diode space-charge region due to shot-noise reduction and space-charge smoothing. For a total space-charge region width of 770 nm, a minimum noise-measure of 22 dB at 60 GHz is obtained. This value reaches almost the theoretical optimum noise measure of pin-avalanche diodes.

Active two-terminal devices as local oscillators for low-noise receiver systems at submillimeter wave frequencies

The power capabilities of three different two-terminal devices, GaAs IMPATT diodes, InP Gunn devices and GaAs TUNNETT diodes are evaluated. Two different selective etching technologies have been employed to fabricate devices on either a diamond heat sink or an integral heat sink. The reported RF power levels in fundamental mode are 20 mW at 120 GHz and 15 mW at 135 GHz for D-band GaAs IMPATT diodes, 21 mW at 120 GHz, 17 mW at 133 GHz and 8 mW at 155 GHz for D-band InP Gunn devices and up to 35 mW around 103 GHz for W-band GaAs TUNNETT diodes. Typical de to RF conversion efficiencies range from 0.9% up to over 4.0%. In second harmonic mode power levels of 0.25 mW at 223 GHz were measured from TUNNETT diodes and 0.4 mW at 220 GHz from a Gunn device.

Studies on the high-frequency properties of ?111?, ?110? and ?100? oriented GaAs IMPATT diodes

High-frequency analysis has been carried out to predict the rf performance of 〈111〉, 〈110〉 and 〈100〉 oriented p+nn+, n+pp+ (single drift region) and n+npp+ (double drift region) GaAs IMPATT diodes for opertion at 35 and 60 GHz. The microwave performance is observed to be highly sensitive to crystal orientation in case of p+nn+ and n+npp+ diodes whereas orientation of the substrate has negligible effect on n+pp+ avalanche diodes. The calculation shows that 〈111〉 oriented GaAs IMPATT diode would provide the largest magnitude of negative resistance and negative conductance for both SDR p+nn+ and DDR n+npp+ diodes which indicates that high microwave power with high conversion efficiency can be realised from these 〈111〉 oriented GaAs devices. This result can be explained from the experimental data of electron and hole ionization rates for different orientations in GaAs.

GaAs single-drift flat-profile IMPATT diodes for CW operation at D band

Single-drift flat-profile GaAs IMPATT diodes were designed for CW operation in the 140GHz range. The diodes were fabricated from MBE grown material, mounted on diamond heatsinks and tested in a radial line full height waveguide cavity. An RF output power of 15 mW with a corresponding DC to RF conversion efficiency of 1.5 % was obtained at 135.3 GHz

Low noise, high efficiency GaAs IMPATT diodes at 30 GHz

Low noise, very high efficiency IMPATT diodes provide an attractive alternative to Gunn diodes for many millimetre-wave applications. In the Letter, GaAs Hi–Lo single-drift IMPATT diodes are demonstrated. The diodes are fabricated using molecular beam epitaxy and (at ~30 GHz) exhibit exceptional efficiencies (>20%), very low FM noise (–88 dBc/Hz at 100 kHz off-carrier) and simultaneous CW power levels in excess of 300 mW.

Temperature dependence of electron saturation velocity in GaAs

Electron saturation velocity is determined from the space charge resistance R/sub c/ and microwave impedance Z/sub d/ of GaAs IMPATT diodes under linear conditions. Comparison between experimental measurement and theory is used in a large frequency bandwidth (2-18 GHz) at different temperatures (T<or=500 K). The results obtained are in good agreement with those of other authors.

Selective etching technology for 94 GHz GaAs IMPATT diodes on diamond heat sinks : Heribert Eisele. Solid-St. Elect.32(3), 253 (1989)

Selective etching technology for 94 GHz GaAs IMPATT diodes on diamond heat sinks : Heribert Eisele. Solid-St. Elect.32(3), 253 (1989)

Selective etching technology for 94 GHz GaAs IMPATT diodes on diamond heat sinks

A selective etching technology has been established for 94 GHz GaAs IMPATT diodes operating on diamond heat sinks. Using this technology diodes were realized delivering an output power of 270 mW. The corresponding efficiency was 5.7% at an oscillation frequency of 95 GHz.

Monolithic millimeter-wave IMPATT oscillator and active antenna

A single-chip millimeter-wave transmitter module in which GaAs IMPATT diodes are monolithically integrated with a microstrip resonator and a loop antenna is discussed. Devices operating at 43.3 GHz produce 27-mW CW output power with 7.2% conversion efficiency. Radiation patterns of linear arrays of such radiating elements were determined as a function of interelement spacing and number of elements. The oscillator chip was also directly coupled to and power combined in waveguides, producing an inexpensive millimeter-wave source. >

Anomalous temperature variation of the thermal resistivity of GaAs IMPATT diodes

The thermal resistivity of GaAs IMPATT diodes was measured from 100-325 degrees C and showed an unexpected 10% decrease, in contrast with the behavior of GaAs MESFET devices, whose resistivity increases as much as 30% over the same temperature range. The most likely explanation of this unusual effect is the dominance of charged impurity scattering in a degenerately doped GaAs contact layer. This may be expected to occur in other devices where heat flow crosses highly doped regions. >

Computation of large signal GaAs impatt diode parameters from closed form analytical solution

The paper discusses the computation of the large signal admittance and power in Read and abrupt junction structures based on the approximate closed form solution and considering the basic device structure parameters. The results have been compared with the simulation results on the more realistic Read model and found satisfactory throughout a fairly large RF voltage range. The applicability of the analysis for optimum device design is as good as the simulation, with the advantages of lower cost and greater simplicity in terms of the computer program involved.

High-power 60 GHz monolithic GaAs impatt diodes

Monolithic GaAs impatt diodes were developed as CW power sources at 60 GHz using double-drift flat-profile structures prepared by MBE. Two mesa-type diodes were employed to excite a microstrip resonator produced on the same chip as the diodes. The oscillation frequency was determined by the microstrip dimensions and the diode locations rather than by external circuitry 1.2 W was obtained at 60 GHz with 8.5% efficiency, and a maximum efficiency of 10% was obtained at 58.5 GHz with 1.1 W output power without the use of diamond heat sinks.

Single-drift flat-profile GaAs impatt diodes at 90 GHz

GaAs impatt diodes were fabricated for the 90 GHz range using the single-drift-region structure with flat doping profile. The diodes were fabricated from molecular-beam-epitaxial material and mounted on diamond heat sinks. A highest output power of 240 mW with 4.1% efficiency at 89.6 GHz was achieved.

Noise Investigation of the Impact Ionization in GaAs

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High-efficiency monolithic GaAs IMPATT diodes

Impedance-matching circuits were integrated on the same chip as the IMPATT diodes to produce monolithic impatt diodes for millimetre-wave applications. A drastic reduction of device-to-circuit parasitic elements was achieved by placing the external circuitry very close to the device. Oscillators fabricated in this fashion gave the highest efficiencies reported so far in the 30–35 GHz range with 28% conversion efficiency using hybrid-Read structures.