STRUCTURAL, OPTICAL, AND SURFACE SCIENCE STUDIES OF 4H-SIC EPILAYERS GROWN BY LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION

A series of epitaxial 4H-SiC thin films grown by low pressure chemical vapor deposition (LPCVD) were characterized using various techniques, including xray diffraction (XRD), Fourier transform infrared (FTIR) r eflectance, Raman scattering, and x-ray photoelectron spectroscopy (XP S). The epilayers were grown on heavily doped n-type 4H-SiC substrates using different gas compositions. XRD showed that the thin films were single crystal. Raman scattering identified the films to be 4H polyty pe. FTIR reflectivity spectra indicated improvement in the film qualit y over that of the substrate and atmospheric pressure-grown epilayers. XPS scans revealed the existence of Si, C, and O along with C-contami nant species in the form of CH and carbon oxides. Variations in crysta lline quality, optical, and surface properties with the growth conditi ons were studied. This study also provides an important comparison bet ween low and atmospheric pressure-grown 4H-SiC epilayers.