Interfacial chemistry and energy band alignment of TiAlO on 4H-SiC determined by X-ray photoelectron spectroscopy

Abstract

Intermixing of TiO2 with Al2O3 to form TiAlO films on 4H-SiC is expected to simultaneously boost the dielectric constant and achieve sufficient conduction/valence band offsets (CBO/VBO) between dielectrics and 4H-SiC. In this work, a composite TiAlO film rather than TiO2-Al2O3 laminations is deposited on 4H-SiC by plasma enhanced atomic layer deposition (PEALD). X-ray photoelectron spectroscopy (XPS) is performed to systematically analyze the interfacial chemistry and energy band alignment between TiAlO and 4H-SiC. An interfacial layer composed of Ti, Si, O and C forms between TiAlO and 4H-SiC during PEALD process. The VBO and CBO between TiAlO and 4H-SiC are determined to be 1.45eV and 1.10eV, respectively, which offer competitive barrier heights (>1eV) for both electrons and holes and make it suitable for the fabrication of 4H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs).