Measurements of off-state electrical stress in InAlN/AlN/GaN heterostructure field-effect transistors with varying In compositions

We report on the electrical stress results in GaN-based heterostructure field-effect transistors (HFETs) with InAlN barriers. We monitored the DC characteristics and low-frequency phase noise behavior for the devices at pre- and poststress conditions for five different wafers with In compositions varying from 12% to 20% in the barriers of the structures. The devices were stressed under off-state conditions with a gate bias of -10V (pinch-off condition) and zero drain bias for 10hr. From the acquired data we observed that at higher In composition, HFETs became less sensitive to the stress. At lower In composition we noted up to 30 dBc/Hz higher low frequency noise for stressed devices over the entire frequency range of 1 Hz-100 kHz. The change in drain current and change in noise power due to electrical stress decrease as the In composition in the barriers of the HFETs increases. The most relevant stress effect is revealed by a drain current reduction which is consistent with higher noise level measured. It was found that the HFET degradation is minimum for nearly lattice matched condition InAlN barriers, i.e.; 17% In composition, at which the sheet electron density (channel current) is comparable with that in lower In composition (12% In). This latter result is promising for power applications in which reliability of devices functioning at higher drain current is crucial. The results may also be beneficial to decouple the effect of off-state stress from the hot electron and self heating effects.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.