ANOMALOUS PHOTOLUMINESCENCE FROM 3C-SIC GROWN ON SI(111) BY RAPID THERMAL CHEMICAL-VAPOR-DEPOSITION

Single crystal 3C-SiC epitaxial films are grown on Si(111) surfaces us ing tetramethylsilane by rapid thermal chemical vapor deposition. Stro ng blue/green photoluminescence (PL) was observed at room temperature from the free films of SiC prepared by etching the Si substrate. The m ain PL peak energy varies from 2.1 to 2.4 eV with full widths at half- maximum between 450 and 500 meV, depending on the growth condition, ex citation wavelength and excitation light intensity. A weak peak at 3.0 eV also appeared. The infrared (IR) spectra of free films of SIC exhi bit modes associated with CH and OH groups. We also compared PL charac teristics of free films of SIC with those from porous SiC produced by anodization of SiC/Si to determine the origin of the FL. Porous SiC sh ows a PL peak centered at 1.9 eV, different from those in SiC. From th e analysis of the IR spectra and scanning electron microscopic images, we tentatively suggest that the origin of the PL from free films of S iC might be associated with an OH group adsorbed on defects or some lo calized states asis the case for an amorphous SixC1-x alloy. (C) 1997 American Institute of Physics.