Chemical Vapor Deposition of Ga₂O₃ Thin Films on Si Substrates

摘要

Amorphous Ga₂O₃ films have been grown on Si(100) substrates by metal organic chemical vapor deposition (MOCVD) using gallium isopropoxide, Ga(Oi Pr)₃, as single precursor. Deposition was carried out in the substrate temperature range 400-800 ∩. X-ray photoelectron spectroscopy (XPS) analysis revealed deposition of stoichiometric Ga₂O₃ thin films at 500-600 ∩. 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∈. The interfacial layer of the Ga₂O₃/Si was measured to be ~35∈ 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.