The physical mechanisms underlying RF current collapse effects in AlGaN-GaN HEMTs are investigated by means of measurements and numerical device simulations. Our study suggests that 1) both surface and buffer traps can contribute to RF current collapse through a similar physical mechanism involving capture/emission of electrons tunneling from the gate; 2) surface passivation strongly mitigate RF current collapse, by reducing the surface electric field and inhibiting electron injection into traps; 3) for surface donor trap densities lower than 9e12 /cm2, surface potential barriers in the 1-2 eV range can coexist with surface traps having much a shallower energy depth and inducing, therefore, current-collapse effects characterized by relatively short time constants.
Effects of surface and buffer traps in passivated AlGaN/GaN HEMTs / Faqir, Mustapha; Verzellesi, Giovanni; Chini, Alessandro; Fantini, Fausto; F., Danesin; F., Rampazzo; G., Meneghesso; E., Zanoni; N., Labat; A., Touboul; C., Dua. - STAMPA. - (2008), pp. 111-112. (Intervento presentato al convegno Workshop On Compound Semiconductor Devices and Integrated Circuits (WOCSDICE) tenutosi a Leuven (Belgium) nel May 2008).
Effects of surface and buffer traps in passivated AlGaN/GaN HEMTs
FAQIR, Mustapha;VERZELLESI, Giovanni;CHINI, Alessandro;FANTINI, Fausto;
2008
Abstract
The physical mechanisms underlying RF current collapse effects in AlGaN-GaN HEMTs are investigated by means of measurements and numerical device simulations. Our study suggests that 1) both surface and buffer traps can contribute to RF current collapse through a similar physical mechanism involving capture/emission of electrons tunneling from the gate; 2) surface passivation strongly mitigate RF current collapse, by reducing the surface electric field and inhibiting electron injection into traps; 3) for surface donor trap densities lower than 9e12 /cm2, surface potential barriers in the 1-2 eV range can coexist with surface traps having much a shallower energy depth and inducing, therefore, current-collapse effects characterized by relatively short time constants.
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