Improved performance of enhancement-mode GaN MIS-FET based on a self-terminating gate recess etching technique with in situ NH3 pre-treatment

Abstract

Based on a self-terminating gate recess etching technique, we successfully fabricated a high-breakdown-voltage and high-threshold-voltage normally-off SiN/AlN/GaN-on-Si metal-insulator-semiconductor-field-effect-transistor (MIS-FET) with optimized PEALD-AlN (plasma-enhance-atomic-layer-deposition) protection layer and in situ NH3 pre-treatment. Compared with thermal-ALD-AlN, the PEALD-AlN protection layer could form a lower interface state density with the GaN channel. Moreover, the in situ NH3 pre-treatment performed in the PEALD system prior to PEALD-AlN deposition could further improve the interface quality. Using in situ NH3 pre-treatment and a PEALD-AlN protection layer, the fabricated SiN/AlN/GaN-on-Si MIS-FET exhibits a high-threshold-voltage of 2.60 V at I D of 1 μA mm−1 (6.57 V by linear extrapolation) and a high-breakdown-voltage of 1775 V.