Chemical vapor deposition of Ga2O3 thin films on Si substrates

Abstract

Amorphous Ga2O3 films have been grown on Si(100) substrates by metal organic chemical vapor deposition (MOCVD) using gallium isopropoxide, Ga(Oipr)3, as single precursor. Deposition was carried out in the substrate temperature range 400-800 °C. X-ray photoelectron spectroscopy (XPS) analysis revealed deposition of stoichiometric Ga2O3 thin films at 500-600 °C. XPS depth profiling by Ar+ ion sputtering indicated that carbon contamination exists mostly in the surface region with less than 3.5% content in the film. Microscopic images of the films by scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed formation of grains of approximately 20-40 nm in size on the film surfaces. The root-mean-square surface roughness from an AFM image was ∼10 Å. The interfacial layer of the Ga2O3/Si was measured to be ∼35 Å thick by cross-sectional transmission electron microscopy (TEM). From the analysis of gaseous products of the CVD reaction by gas chromatography-mass spectrometry (GC-MS), an effort was made to explain the CVD mechanism.