Reliability of InAlN/GaN High Electron Mobility Transistors

InAlN/GaN High-Electron Mobility Transistors (HEMTs) are very promising for high-power and high frequency applications. In comparison with the better established AlGaN barrier layer, the use of an InAlN barrier yields, for the same layer thickness, a higher spontaneous polarization induced charge at the barrier/GaN interface. This enables aggressive barrier thickness scaling and gate length scaling which are key for high frequency operation. An additional benefit of this material system is that with the right composition, InAlN can be lattice matched to GaN. This eliminates internal stresses in the barrier that are believed to compromise the reliability of AlGaN/GaN HEMTs.

Unlike the better understood AlGaN/GaN system, the physics behind the degradation of InAlN/GaN HEMTs after prolonged electrical stress are not well established. Our project aims to address this void by studying the leading degradation modes of these devices under different stress conditions with the ultimate goal of constructing models to predict device lifetime.