AlGaN/GaN devices for future power switching systems

GaN/AlGaN device technologies are presented aiming at the applications to power switching systems. In order to reduce on-resistance (R_on), we developed SL (super lattice) capping and QA (quaternary alloy) over-layer techniques for GaN/AlGaN HFET. Further, we achieved almost the same mobility keeping the same 2DEG density for GaN/AlGaN hetero structure grown on Si (111) substrates, which will make the cost comparable to conventional Si one. The experimentally obtained R_onA of the FET is 1.9 mOmegacm², which is 14 times lower than that of Si ones. Additionally, a novel approach to realize enhancement-mode operation of GaN/AlGaN FET is examined over R-plane sapphire, where non-polar AlGaN/GaN heterostructure, free from polarization charge, can be grown