Effects of surface plasma treatment on threshold voltage hysteresis and instability in metal-insulator-semiconductor (MIS) AlGaN/GaN heterostructure HEMTs.

In a bid to understand the commonly observed hysteresis in the threshold voltage (<italic>VTH</italic>) in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors during forward gate bias stress, we have analyzed a series of measurements on devices with no surface treatment and with two different plasma treatments before the <italic>in-situ</italic> Al2O3 deposition. The observed changes between samples were quasi-equilibrium <italic>VTH</italic>, forward bias related <italic>VTH</italic> hysteresis, and electrical response to reverse bias stress. To explain these effects, a disorder induced gap state model, combined with a discrete level donor, at the dielectric/semiconductor interface was employed. Technology Computer-Aided Design modeling demonstrated the possible differences in the interface state distributions that could give a consistent explanation for the observations. [ABSTRACT FROM AUTHOR]