Mobility enhancement in recessed-gate AlGaN/GaN MOS-HFETs using an AION gate insulator

We demonstrated the advantage of aluminum oxynitride (AION) gate insulator in enhancing the performance of recessed-gate AlGaN/GaN-based metal-oxide-semiconductor heterojunction field-effect transistors (MOS-HFETs) fabricated with reactive ion etching. The AION deposition on the recessed-gate structures was found to mitigate the damage of recess etching on the GaN and AlGaN surfaces, enabling a simple gate recess process in the device fabrication. Consequently, a high field-effect mobility of 259 cm(2) V-1 s(-1), together with normally off operation, was achieved for the recessed-gate AlGaN/GaN MOS-HFETs with the AION gate insulator. Temperature dependence of the transconductance of the fabricated devices revealed that carrier transport in the channel was mostly dominated by phonon scattering, indicating excellent interface quality between the AION insulator and the recess-etched AlGaN surfaces. (C) 2019 The Japan Society of Applied Physics