Advancements in ohmic contact technology for AlGaN/GaN high-electron-mobility transistors

Abstract

AlGaN/GaN-based high electron mobility transistors (HEMTs) hold significant technological importance due to their applications in power electronics, radio frequency (RF) amplifiers, and microwave communication systems. A critical factor affecting the performance of AlGaN/GaN HEMTs is the formation of high-quality ohmic contacts to the source and drain, which facilitates efficient carrier injection from metal electrodes to the semiconductor. Therefore, various approaches have been employed to achieve the formation of high-quality ohmic contacts. This review presents recent advancements in ohmic contact technology for AlGaN/GaN HEMTs. Specifically, we introduce and discuss contact technologies focusing on multilayer schemes under different annealing conditions, Au-free metallization schemes, surface treatments, non-traditional annealing processes, recess etching, selective area regrowth, and ion implantation.