Kink effect in HEMT structures: A trap-related semi-quantitative model and an empirical approach for spice simulation

Abstract The mechanism of kink effect in AlGaAs/GaAs high-electron-mobility transistors (conventional, normally-on) is reported. An analytical model, in good agreement with experimental results (behaviour of the kink voltage with temperature and gate voltage) shows that this effect is related to impact ionization phenomenon. Accurate prediction of the I − V characteristics including the kink effect can be carried out, extending the d.c.-equations of the SPICE GaAs-FET model. Three parameters are used in the kink region for the drain current. All of them are extracted from experimentally measured I − V characteristics and preserve physical meaning.