In-situ P doped epitaxial Si_1-xC_xgrowth under UHV-CVD

Undoped and in-situ phosphorus-doped epitaxial Si_1-xC_xlayers were grown on chemically cleaned Si (100) substrates by using a UHV-CVD process. The carbon concentrations of the epitaxial layers and growth temperatures were varied, and the effects of post annealing processes were then investigated. In the defect-free films, the carbon content in the Si_1-xC_xlayer was analyzed to be about 1.2% by XRD measurement. About 20% loss of the substitutional carbon atoms occurred after annealing treatment at 1000°C in N₂ambient due to the transfer of the substititual carbon atoms to interstitial sites as well as the formation of the β-SiC precipitates. The changes in microstructures were analyzed by the cross sectional transmission electron microscopy. The surface of the films shows partially polycrystalline structures in high PH₃flow rate, due to surface poisoning by phosphorus segregation. Fully a 100% substitutionality of carbon atoms in the epitaxial Si_1-xC_xfilm is achieved by the addition of PH₃and post annealing.