Double Drift Region Research Articles

Saturation current induced effects on the microwave and millimetre wave performance of GaAs double drift region IMPATTs

Abstract Computer studies have been carried out to study the role of electron and hole saturation currents on the microwave and millimetre-wave performance of a GaAs double drift region (DDR) IMPATT. It has been found that (i) the device negative conductance and (ii) the device negative resistance both decrease with increase of either electron or hole saturation current, i.e. with the decrease in either electron or hole multiplication factor. It has also been observed that the frequency of operation shifts upwards and the device quality factor increases gradually with increasing saturation current. It has further been observed that the upward shift in operating frequency is more when the GaAs DDR IMPATT performance is controlled by the hole saturation current rather than by the electron dominated saturation current. The relative predominance of the hole saturation current over the electron saturation current in inducing the higher frequency shift of the GaAs DDR IMPATT may be explained in terms of the ine...

A Study on the Effect of Electron and Hole Saturation Currents on the Negative Resistance Profiles, Negative Conductance and the Frequency of Operation of Millimeter Wave (W-Band) Double-Drift Silicon IMPATT Diodes

Computer studies have been carried out on the effect of electron and hole reverse saturation current on the high frequency (i) negative resistance and reactance profiles, (ii) admittance characteristics, and (iii) device quality factor of a silicon double-drift region (DDR) IMPATT operating in the mm-wave range (W-band). The results indicate that the negative resistance peaks in the electron and hole drift layers decrease with increasing reverse saturation current. The total diode negative resistance also decreases appreciably with the increase of either electron or hole reverse saturation current, ie, with decrease in electron or hole current multiplication factors (M & Mp).It has further been observed that in the lower frequency range of the W-band, the device negative conductance decreases with the increase of reverse saturation current, while in the frequency range from 160–210 GHz, the device negative conductance increases with the enhancement of reverse saturation current.An upward frequency shift b...

Small-signal computer simulation of IMPATT diodes including carrier diffusion

A generalized computer simulation method for small-signal analyses of IMPATT diodes incorporating the carrier diffusion current is presented. The method is capable of predicting the effect of carrier diffusion on the integrated device's microwave characteristics as well as on individual space-step contributions to diode negative resistance which in turn can identify the diode zone where carrier diffusion would have a pronounced effect. The results of author's investigation on the effect of carrier diffusion on performance of silicon flat-profile p+nn+, n+pp+ and n+npp+ diode structures indicate that diffusion has a pronounced effect on the p-side of the diodes whereas its effect on the n-side is only marginal. The changes in the values of diode negative conductance and diode negative resistance of the silicon flat-profile double-drift region diodes are observed to remain within ten per cent if the frequency of operation is kept within 100 GHz.

The distribution of negative resistivity in the active layer of millimetre-wave double-drift region diodes

A computer study of the high-frequency negative resistivity distribution profiles in the active layer of double-drift-region (DDR) silicon IMPATT diodes for operation at atmospheric window frequencies in the millimetre-wave range is presented. Iterative simulation programmes have been framed for static and high-frequency realistic analyses of IMPATT diodes. These analyses provide an insight into the relative contribution to microwave power produced by two types of charge carriers in their respective drift regions, and also a knowledge of the intensity of IMPATT oscillation at various space points of the active layer. The negative resistivity profiles exhibit one peak in the middle of each drift layer separated by a minimum in the avalanche layer. This indicates that the drift regions of the diode are major contributors to microwave power generated by a DDR IMPATT device. The space distribution of negative resistivity, as well as the magnitudes of the negative resistivity peaks, depends on the ionisation rates of electrons and holes in silicon and on the mobile space-charge density.

High frequency characterisation of double drift region InP and GaAs diodes

Computer studies have been made on the high frequency characteristics of symmetrically doped flat profile double drift region (DDR) InP and GaAs impatts in the mm-wave (60–100 GHz) frequency band. The spatial distribution of high frequency negative resistance and reactance in the depletion layer of DDR devices and their admittance properties have been investigated. The results indicate that DDR InP impatts should have higher drift zone voltage drop, higher negative resistance and higher negative conductance compared to their GaAs counterparts designed for the same range of mm-wave frequencies. Furthermore, the negative resistance peak is larger in magnitude for InP impatts compared to that for GaAs impatts. It is thus observed that DDR InP impatts should be superior to their GaAs counterparts as regards mm-wave power generation with high conversion efficiency.

Computer-aided analysis of double drift region impatt diode

The results calculated by computer for the double drift region IMPATT diode oscillator on the 8 mm waveband are reported in this paper. A comparison between single and double drift devices concerning the power output and efficiency is given. The effect of doping profile, current density and RF voltage on the performances of these devices have also been investigated. The theoretical data of these double drift IMPATT oscillator and amplifier are provided.

Computer studies of the effect of electron and hole current multiplication factors on the d.c. and microwave properties of symmetrical Si DDR IMPATT devices

Computer studies are presented on the effect of carrier current multiplication on the d.c. field and current profiles and the small-signal admittance of a symmetrical Si double-drift region (DDR) IMPATT diode, taking into account the realistic field dependence of ionization rate and drift velocity of charge carriers and also the effect of mobile space-charge. The d.c. field and current profiles indicate that the lowering of the electron current multiplication ( M n ) is more effective than the lowering of hole current Multiplication factor ( M p ) in modifying the d.c. properties of Si DDR devices. The computer-aided small-signal analysis carried out for the same structure shows that, a lowering of M n leads to a sharp decrease of the peak value of the small-signal negative conductance at a fixed d.c. current density which is accompanied by a shift of the frequency range of oscillation towards the higher frequency side.

On the theory of the avalanche transit-time diode reflection amplifier†

Abstract A comparatively simple non-linear analytical theory of the IMPATT diode has been developed which accounts for a finite thickness of the avalanche region. Single and double drift region encapsulated and non-encapsulated diodes have been investigated in reflection amplifiers where the circulator is an integral part of the broad-band matching network. It is demonstrated that large bandwidths are possible and that the IMPATT diode amplifier has some important non-linear properties in common with the TWT.

High-power millimeter wave IMPATT oscillators with both hole and electron drift spaces made by ion implantation

CW powers of 640 mW at 50 GHz have been obtained from double-drift region IMPATT diodes. This result represents the highest product of CW power times frequency squared obtained to date from any IMPATT diode. The diodes are p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> pnn <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> structures and have both hole and electron drift spaces. The systematic fabrication (by ion implantation) and the evaluation of the dc and millimeter wave characteristics are presented.