Monte carlo particle study of transport along the hetero interface in a field‐effect transistor

Rees

David

1997

We have investigated impact ionization in a small 1.2 µm MESFET by means of Monte Carlo simulation. Whilst ionization in devices operating near pinch-off was found to occur in accordance with the nominal gate-drain electric field, it was found that at lower gate reverse bias the device was vulnerable to oscillating electric fields associated with the formation of accumulation layers. These fields caused significant impact ionization to occur at relatively low nominal gate-drain potentials. Indeed the newly formed holes could have a positive feedback effect on the potential causing the oscillations to increase and the device to eventually break down. Under certain circumstances, the accumulation layer oscillations were stable and the device oscillated with a frequency of ≈125 GHz, though as the displacement current was out of phase with the carrier current, the total current was found to have little more than a ripple on it.

Section: Introductionmentioning

confidence: 99%

Simulation of impact ionization breakdown in MESFETS using Monte Carlo methods

Rees

David

1997

Current instability in power HEMTs

Phillips

Topham

2001

We present an experimental and theoretical study of current instability in an Al 0.23 Ga 0.77 As/In 0.23 Ga 77 As n-channel delta-doped pseudomorphic high electron-mobility transistor (HEMT). Monte Carlo simulations of the device indicated that it was vulnerable to the formation of unusual 'transverse' Gunn dipoles which caused sudden reductions in the drain current. These dipoles were also responsible for a significant number of impact ionization events at higher drain potentials causing a subsequent upturn in the drain current. Our experimental observations of a similar device are in excellent qualitative and good quantitative agreement with our theoretical predictions and so provide compelling evidence for the existence of Gunn instabilities in HEMTs.

Gunn oscillations in planar heterostructure diodes

Pilgrim

Khalid

et al. 2008

Gunn oscillations have been observed and modelled, using a Monte Carlo method, in planar semiconductor GaAs/AlGaAs heterostructure diodes. Our simulation results support an interpretation of experimental results whereby the Gunn domains travel parallel to the semiconductor layers, as opposed to perpendicular to the layers in traditional vertical devices. Fabricated devices with contact separations of 4 µm down to 1.3 µm have been found to oscillate over a range of frequencies from 24.5 GHz to 108 GHz. These structures offer the prospect of generating frequencies further into the terahertz range and an increased ease of integration and flexibility over equivalent traditional vertical structures.