Chemical Vapor Deposition of Ga₂O₃Thin Films on Si Substrates

Abstract

Amorphous <TEX>$Ga_2O_3$</TEX> films have been grown on Si(100) substrates by metal organic chemical vapor deposition (MOCVD) using gallium isopropoxide, <TEX>$Ga(O^iPr)_3$</TEX>, as single precursor. Deposition was carried out in the substrate temperature range 400-800 <TEX>$^{\circ}C$</TEX>. X-ray photoelectron spectroscopy (XPS) analysis revealed deposition of stoichiometric <TEX>$Ga_2O_3$</TEX> thin films at 500-600 <TEX>$^{\circ}C$</TEX>. XPS depth profiling by <TEX>$Ar^+$</TEX> 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 <TEX>${\sim}10{\AA}$</TEX>. The interfacial layer of the <TEX>$Ga_2O_3$</TEX>/Si was measured to be <TEX>${\sim}35{\AA}$</TEX> 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.