A review of selective area grown recess structure for insulated-gate E-mode GaN transistors

Abstract

Recess structure is one of the main schemes for insulated-gate E-mode GaN transistors. In this work, selective area growth (SAG) is proposed to fabricate damage-free recess-gate device, and related progresses regarding process optimization and structure evolution have been reviewed. Firstly, the SAG process has been optimized by interface separation (conduction interface and regrowth interface) and n-type Si impurity removal to achieve high-quality AlGaN/GaN heterostructure. Compared to the traditional etching method, the feasibility and superiority of SAG scheme are demonstrated for realizing E-mode Al2O3/GaN MISFET with small Vth hysteresis. Then, by inserting an in situ AlN interlayer, the SAG Al2O3/AlN/GaN MISFET yields improved frequency dispersion and gate channel conduction performances. To further enhance the channel conduction, the SAG partially recess-gate Al2O3/AlGaN/GaN MIS-HFET structure is proposed, by which both high Vth and high-field-effect channel mobility have been achieved. Those results indicate that SAG method gives a perspective way for insulated-recess-gate GaN transistors fabrication.