Current instability in power HEMTs

Abstract

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.

Numerical modeling of TeraHertz electronic devices

“…This is exactly what is observed in the experimental spectra [38]. Looking at the experimental I-V curves which exhibit kinks in correspondence to the onset of THz emission [38] one may think that the detected emission could take place due to Gunn oscillations since their onset leads to a decrease of the drain current, and this effect has already been experimentally detected in HEMTs [42]. In order to explain the origin of the emission we have performed MC simulations of HEMTs with different geometries and we have observed that, under certain conditions, Gunn oscillations take place when V DS is higher than a given threshold value as shown in Fig.…”

Review of electron transport properties in bulk InGaAs and InAs at room temperature

“…The scattering mechanisms which are included in the physical model are the following: collisions with ionized impurities (Brooks-Herring model), transitions due to absorption and emission of polar and non-polar optical phonons, collisions with acoustic elastic phonons, intervalley and alloy scatterings [23]. In particular, the impact ionization has been treated in the framework of the Keldysh approach [12,[24][25][26][27] where the probability per unit of time is given by (1) where A is a coeficient which indicates the strength of the scattering process and ϵ th is a threshold energy. The parameter ϵ th can be calculated using the Anderson and Crowell criteria [28] or following the procedure outlined by Quade et al [29].…”

Monolithic fabrication of a planar Gunn diode and a pHEMT side-by-side

“…However, Gunn instabilities on a pHEMT substrate have been reported in the past indicating the high possibility of the successful fabrication of both devices using the same active layers [10]. We show the implementation of a planar Gunn diode and a FET side-by-side on the same substrate for the first time.…”