Title :
Inclusion of impact ionization in the backgating of GaAs FETs
Author :
Li, Z.M. ; Day, D.J. ; McAlister, S.P. ; Hurd, C.M.
Author_Institution :
Nat. Res. Council of Canada, Ottawa, Ont., Canada
Abstract :
It is shown that the familiar threshold behavior of the backgate current of GaAs MESFETs has hysteresis. This is associated with an S-type negative differential conductivity (S-NDC) of the semi-insulating substrate. It is difficult to account for this hysteresis using conventional trap-fill-limited (TFL) theory, and it is attributed to the impact ionization of traps in the substrate. A simple model of this ionization, involving two trap levels, is used to incorporate its effect into an existing analytical model of GaAs FETs. The result is a qualitative interpretation of the backgating characteristics of GaAs MESFETs. The calculations show that a simple combination of two ohmic elements to represent parasitic resistances, and a nonohmic one to represent impact ionization in the substrate, can imitate the observed backgating behavior.<>
Keywords :
III-V semiconductors; Schottky gate field effect transistors; gallium arsenide; impact ionisation; negative resistance; semiconductor device models; GaAs; MESFET; S-type negative differential conductivity; analytical model; backgate current; backgating characteristics; hysteresis; impact ionization; nonohmic element; ohmic elements; parasitic resistances; semi-insulating substrate; threshold behavior; trap-fill-limited theory; Analytical models; Conductivity; Delay effects; FETs; Gallium arsenide; Hysteresis; Impact ionization; Insulation; MESFETs; Voltage;
Journal_Title :
Electron Device Letters, IEEE
