ON-state breakdown mechanism of GaN power HEMTs

Temperature-dependent ON-state breakdown (BV
ON
) loci of AlGaN/GaN high-electron-mobility transistors (HEMTs) were experimentally demonstrated for the first time. With gate-current extraction technique, impact ionization was revealed to be responsible for the ON-state breakdown in our device as the HEMTs is marginally turned on. The characteristic electric-field E
i
of impact ionization was extracted exhibiting an U-shaped temperature dependence from 40 to −30 ºC, with minimum E
i
occurs at −10 ºC. Such anomalous temperature dependence of E
i
together with the kink effect observed in our devices stem from coulomb scattering effect of the acceptor-like traps in AlGaN/GaN heterostructures.