J. P. Banerjee

Effect of punch through factor on the breakdown characteristics of 4H-SiC IMPATT diode

Computer simulation has been carried out to investigate the effect of punch through on the breakdown properties such as peak electric field, breakdown voltage and DC-to-RF conversion efficiency of 4H p+nn+ SiC Impatts. The effect of mobile space charge and diffusion has been incorporated in the analysis. The results indicate increase of junction field at breakdown with sharp decrease of breakdown voltage with increasing punch through factors. It has also been observed that the diode exhibits a space charge induced positive resistance which decreases at higher doping levels. A comparative study reveals that higher DC-to-RF conversion efficiency and higher breakdown voltage can be obtained from 4H-SiC Impatts than from Si Impatts.

A proposed method to study the parasitic resistance of Ka-band Silicon IMPATT diode from large-signal electric field snap-shots

In this paper a novel method based on the concept of time varying depletion width modulation at large-signal levels is proposed to obtain the parasitic resistance of the inactive region of Ka-band Silicon Single-Drift Region (SDR) Impact Avalanche Transit Time (IMPATT) diodes. A complete simulation software based on non-sinusoidal voltage excitation method is developed to obtain the large-signal electric field snap-shots of the device at different bias current densities and different phase angles of a full cycle of steady-state oscillation from which the parasitic series resistance of the device is calculated. The series resistance is also calculated from the conventional method i.e., from the large-signal admittance characteristics at threshold frequency. The results however show that the proposed method to determine the series resistance provides better and closer agreement with the experimentally reported value than the conventional method.

Millimeter-wave and noise properties of Si∼Si 1−x Ge x heterojunction double-drift region MITATT devices at 94 GHz

The authors have made an attempt to study the millimeter-wave properties and noise performance of Si~Si1-xGex anisotype heterojunction Double-Drift Region (DDR) Mixed Tunneling Avalanche Transit Time (MITATT) devices operating at 94 GHz. A computer simulation technique based on driftdiffusion model is used for the present study. Two different mole fractions, x = 0.1 and x = 0.3 of Ge and four types of device structure are considered for the simulation. The results show that the n-Si0.7Ge0.3~p-Si heterojunction DDR structure of MITATT device excels all other structures as regards DC to RF conversion efficiency (20.15%), CW power output (773.29 mW) and noise measure (33.09 dB).

A proposed theoretical model of Impact Ionization rate under carrier degeneracy considering different scattering phenomena

A theoretical model of Impact Ionization rate is proposed in this paper. Multistage scattering processes are considered which incorporate electron-electron scattering, hole-hole scattering, optical phonon scattering and impact ionization. The effect of high carrier concentration on carrier mobility and effective mass has been taken into account and the resulting modification in the ionization rate has been incorporated. The proposed theoretical model is simulated for GaAs and the results are found to be in close agreement with available experimental results.

Mobile space charge effect in 4H Silicon Carbide IMPATT diodes

The effect of mobile space charge in the depletion layer of 4H SiC p⁺nn⁺ IMPATT diode has been investigated through computer simulation method. The simulation is based on drift-diffusion model to study DC properties of the device at different bias current densities. The device is designed to operate at millimeter wave frequencies. It is observed that a maximum DC to microwave conversion efficiency of 22.82% is obtained at a bias current density of 4.4times10⁷ A.m². The DC to microwave conversion efficiency of Read and Quasi Read High-low SDR diodes has also been estimated and compared with that of flat profile p⁺nn⁺ diode at the same bias current density of 4.4times10⁷ A.m².