Effective Reduction of Current Collapse in AlGaN/GaN MISHEMT via Low-Temperature Nitriding Treatment

Abstract

We successfully demonstrated a 72% reduction in current collapse under high-field driving conditions ( ${V}_{\text {D}} =300$ V) for AlGaN/GaN MISHEMT using low-temperature supercritical fluid nitridation (SCFN) treatment at $180~^{\circ }$ C for 1 h. A significant improvement in the off-state ( ${V}_{\text {G}}= -10$ V) gate leakage current was observed in MISHEMT with SCFN treatment, resulting in a high breakdown voltage (BV) capability of up to ${V}_{\text {D}}=710$ V (at $1~\mu $ A/mm), compared to only ${V}_{\text {D}}=110$ V without SCFN. Furthermore, in terms of characteristics, the device was improved with a 4.6% increase in maximum drain current ( ${I}_{\text {D},\max }$ ), a 2.9% increase in maximum transconductance ( ${G}_{\text {m},\max }$ ), and an 11.1% decrease in drain-source on resistance [ ${R}_{\text {DS}}$ (on)]. These improvements can be attributed to the repairs of dangling bonds on the AlGaN surface and the elimination of the Al2O3/AlGaN interface traps, which collectively lead to improved performance and stability. Based on the abovementioned results, the X-ray photoelectron spectroscopy (XPS), conduction band edge of defect state density ( ${D}_{\text {it}}$ ), and gate leakage trap-related hopping conduction mechanism were analyzed to explain the phenomenon.