Epitaxial growth of layered structures of silicon carbide and aluminum nitride by metal-organic chemical vapor deposition.

摘要

In this study, individual layers and heterostructures of AlN and SiC were grown on various substrates by metal-organic chemical vapor deposition (MOCVD) with TMA, NH{dollar}sb3{dollar}, SiH{dollar}sb4{dollar}, and C{dollar}sb2{dollar}H{dollar}sb4{dollar} as the precursors for Al, N, Si, and C, respectively. The grown films were characterized by X-ray diffraction, scanning electron microscopy, UV absorption spectroscopy, and some other analytical techniques.; For individual layer growth, epitaxial AlN films were obtained on c-Al{dollar}sb2{dollar}O{dollar}sb3{dollar}, r-Al{dollar}sb2{dollar}O{dollar}sb3{dollar}, and 6H-SiC substrates at temperatures higher than 1100{dollar}spcirc{dollar}C. The AlN films grown on 6H-SiC had superior crystal quality and surface morphology. Epitaxial SiC films were grown on Si(100) and Si(111) substrates at 1350-1400{dollar}spcirc{dollar}C with a two-step process. Deposition of SiC on bare Al{dollar}sb2{dollar}O{dollar}sb3{dollar} substrates resulted in peeled-off films or no growth at all.; For layered growth of AlN and SiC, AlN films grown on SiC/Si(100) were polycrystalline and exhibited the wurtzite structure. SiC films grown on AlN/Si(111) appeared to be single crystal when the AlN layer was very thin (0.1 {dollar}mu{dollar}m). Epitaxial 6H-SiC films were grown on AlN/Al{dollar}sb2{dollar}O{dollar}sb3{dollar} and AlN/6H-SiC substrates at 1375{dollar}spcirc{dollar}C. Double crystal X-ray rocking curve studies have shown that the defect density in the SiC layers on AlN/c-Al{dollar}sb2{dollar}O{dollar}sb3{dollar} was in the order of {dollar}10sp{lcub}10{rcub}{dollar} cm{dollar}sp{lcub}-2{rcub}{dollar}, slightly superior to that of SiC on Si(111) substrate.; All the SiC films grown in this study showed n-type conductivity with undesirable electrical characteristics such as low ({dollar}10sp{lcub}-3{rcub}Omega{dollar} cm) resistivities, low ({dollar}{rcub}10sp{lcub}19{rcub}{dollar} cm{dollar}sp{lcub}-3{rcub}){dollar} carrier concentrations. Contamination from nitrogen and oxygen was responsible for these degraded properties.