Suppression and characterization of interface states at low-pressure-chemical-vapor-deposited SiN /III-nitride heterostructures

• DOI: 10.1016/j.apsusc.2020.148530
• Publication Date: 2020-12-05T01:28:28Z
• Authors: Kexin Deng; Xinhua Wang; Sen Huang; Haibo Yin; Jie Fan; Wen Shi; Fuqiang Guo; Ke Wei; Yingkui Zheng; Jingyuan Shi; Haojie Jiang; Wenwu Wang; Xinyu Liu
• Keywords: Deep-level transient spectroscopy; Saturation (graph theory)

Abstract Silicon nitride (SiNx) grown by low-pressure chemical vapor deposition (LPCVD) at a reduced growth temperature (650 °C), is utilized for fabrication of GaN metal–insulator-semiconductor (MIS) power devices. An atomically sharp interface between the LPCVD-SiNx and GaN was achieved, featuring a disordered region with only a thickness of 2.5 ~ 5 A. A fabricated LPCVD-SiNx/GaN/AlGaN/GaN MIS diode exhibits a sharp two-step capacitance–voltage behavior with small frequency dispersion of 0.4 V in the right step. The improved interface was quantified by a well-elaborated constant-capacitance deep-level transient Fourier spectroscopy (CC-DLTFS), delivering quite low density of 1.5 × 10 13 cm - 2 eV - 1 at the level depth of 30 meV and about 4 × 10 11 ~ 1.2 × 10 12 cm - 2 eV - 1 at the level depth of 1 eV. Distributions of interface states can be described by a proposed physics-based decoupling function featuring an exponential law. A discrete level at the SiNx/GaN border or in the barrier layer with the level depth and the capture cross section being 0.8 eV and 5.5 × 10 - 14 cm 2 respectively, can thus be detached from the interface states.