Parasitic side channel formation due to ion implantation isolation of GaN HEMT

Abstract

Low-dose high-energy ion implantation is effective for isolating GaN high-electron-mobility transistors (HEMTs). However, lateral penetration of implanted ions induces damages at sides of AlGaN/AlN/GaN HEMTs and causes parasitic channel formation. By comparing ion implantation isolated HEMTs with varied widths, the parasitic channel behavior is characterized: the parasitic channel shows low on-state conductance, reduced gate current, and more positive threshold voltage compared to the active HEMT channel. The high N ion implantation energy for HEMT isolation was up to 375 keV, and the effective widths of HEMTs are narrowed by similar to 0.5 mu m. The electrical characteristics of the parasitic channel are theoretically understood by considering ionization of point defect generated in the AlGaN/AlN/GaN heterostructures.