Comparison of SiO2-based double passivation scheme by e-beam evaporation and PECVD for surface passivation and gate oxide in AlGaN/GaN HEMTs

Abstract

Double-insulator scheme by different deposition methods are first studied.E-beam-based SiO2 shows the best result due to the reduction of gate leakage current.E-beam-based SiO2 and double scheme form a competitive insulator for HEMT.Authors plan to try other tool, such as LPCVD, TCVD and ADM to obtain optimal result. This study investigates and compares AlGaN/GaN high electron mobility transistors (HEMTs) with three different configurations: an as-fabricated HEMT, a HEMT that uses SiO2 for surface passivation and a gate oxide that has been deposited using an electron beam (e-beam) evaporation deposited method, and a HEMT that uses SiO2 for surface passivation and a gate oxide that has been deposited using a plasma-enhanced chemical vapor deposition (PECVD) method. The study found that the e-beam-evaporated SiO2 improves maximum saturation current density, peak extrinsic transconductance, and breakdown voltage by 10%, 13%, and 6%, respectively, over the performance of the PECVD-deposited SiO2 HEMT, due to the reduction of the gate leakage current, and this method provides an improvement of 28%, 25%, and 25% over the performance of the regularly fabricated HEMT.