Defect analysis of Sn-doped Ga2O3/SiC hetero-structured Schottky diodes using deep level transient spectroscopy

Abstract

The Sn-doped β-Ga2O3 films were fabricated on n-type 4H-SiC substrates using Mist-chemical vapor deposition with different [Sn]/[Ga] ratios of 0%, 3%, 5%, and 10%. For device fabrication, Ni Schottky contacts were deposited on the Ga2O3 epilayer by electron-beam evaporation, forming Ga2O3/SiC hetero-structured Schottky barrier diodes. The deposition influence on the chemical state, electrical properties, and deep-level traps of Sn-doped Ga2O3 films were thoroughly investigated. In J–V characteristics, the Ga2O3 film with 3% [Sn]/[Ga] ratio showed the highest conducting properties and lowest Ron,sp and leakage current. The results of x-ray photoelectron spectroscopy demonstrated that Sn atoms were successfully doped in these films, and the formation of SnO and SnO2 could be inferred based on the [Sn]/[Ga] ratio. Deep-level transient spectroscopy (DLTS) identified the Z1/2 center (carbon vacancy, VC) in 4H-SiC for the undoped device and for the SiC epitaxial sample. In Sn-doped devices, Sn-related levels (SnGa) were observed, and the Z1/2 signal was not detected within our measurement sensitivity. In addition, at higher Sn concentrations, VO-related defects were detected, which could degrade the leakage current and carrier lifetime. This study provides a pathway to optimize the fabrication of high-performance Sn-doped Ga2O3/SiC heterojunction diodes with minimized defect density and enhanced electrical properties.