Photoluminescence study of epitaxial 4H-SiC grown on AlN/Si(100) complex substrate by chemical vapor deposition

Epitaxial 4H-SiC grown on AlN/Si(100) complex substrate by chemical vapor deposition (CVD) at the relatively low temperature was investigated. During the growth, ethylene and silane were used as the precursors and hydrogen as the carrier gas. The structural and optical properties of the epitaxial film were characterized by various methods. The results of X-ray diffraction (XRD) and Raman scattering show that the obtained epilayer is monocrystalline hexagonal SiC. By the Auger electron spectrum (AES), the thermal diffusion of Al and N from the AlN buffer layer to the SiC epitaxial layer was observed. Al and N were proved to be substitute for Si and C respectively in the SiC layer by the X-ray photoelectron spectrum (XPS). The room-temperature photoluminescence (PL) consisted with the Al acceptor level and the N donor level was observed at 3.03 eV and 3.17 eV, respectively. The obtained epitaxial SiC layer was thus proved to be 4H polytype. A PL peak corresponding to the recombination between the secondary conduction band minimum of 4H-SiC and the Si-vacancy acceptor level was also observed at 3.37 eV.