Demonstration of AlGaN/GaN High Electron Mobility Transistors on a-Plane (11(2)over-bar0) Sapphire

The AlGaN/GaN heterostructures (HSs) with reduced dislocation density were grown on 4-in. a-plane sapphire substrate. The two-dimensional electron gas (2DEG) was observed for AlGaN/GaN HSs on a-plane sapphire. A complete pinch off AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated with a maximum drain current density (I-DSmax) of 551 mA/mm and transconductance maximum (g(mmax)) of 134 mS/mm. Compared to c-plane grown HEMTs, two orders of magnitude low gate leakage current was observed on a-plane grown HEMTs with enhanced barrier height. The low gate leakage is due to enhanced Schottky barrier height and reduced dislocation density of GaN grown on a-plane sapphire. [DOI: 10.1143/JJAP.47.3332]