抄録
This paper describes reliability of AlGaN/GaN heterostructure field-effect transistors fabricated on Si substrates. At an early stage of 50 V high temperature operating life tests, they exhibited a significant lowering of the forward turn-on voltage. The mean time to failure (MTTF) determined by this degradation mode was exponentially increased by decreasing full width at half maximum values of x-ray rocking curves. High-resolution transmission electron microscope and energy dispersive x-ray spectroscopy analyses revealed thinning or partial vanishment of GaN cap layer in a degraded sample. To account for these experimental findings, degradation mechanism assuming diffusion of interfacial materials along dislocations was discussed. An improved device operating at 50 V, where this degradation mode was suppressed, exhibited an MTTF exceeding 1×106 h at a channel temperature of 150℃.
