(Invited) Investigations and Improvements of AlInN/GaN HEMTs Grown on Si

GaN-based high electron mobility transistors (HEMTs) have attracted tremendous attention because of its wide bandgap and high power handling capability, which are the two fundamental merits for power electronics applications. Lattice-matched AlInN/GaN heterostructure has been considered a promising alternative to its AlGaN/GaN counterpart due to its stronger spontaneous polarization, which induces higher carrier concentration and therefore reduces channel resistance. In addition, InAlN lattice-matched to GaN would not be subject to the inverse piezoelectric effect that deteriorates device reliability as observed on AlGaN/GaN HEMTs.  While a few excellent device characteristics have been demonstrated over the years, AlInN/GaN HEMTs are in general still more vulnerable than AlGaN/GaN HEMTs. It is desirable to clarify the origin(s) of this problem to expedite the development of high power AlInN/GaN HEMTs and the devices alike. In this talk, we will present our recent works on the growth and electrical characterization of AlInN/GaN HEMTs, including capping layer designs, off-state breakdown mechanisms, dynamic resistance measurements as well as low frequency noise measurements. Solutions to cope with the material issues and process issues will also be addressed.