SEGREGATION ENHANCED Ge_(1-x)Sn_x NANOCRYSTAL FORMATION ON SILICON SUBSTRATE

摘要

Thin layers of SiGeSn alloys were deposited on (001) Si wafers by MBE followed by thermal treatment at 600-1000℃ for 10-150 min in N_2 or O_2 atmospheres. Based on TEM and RBS investigations, we report on phase separation and Sn surface segregation after treatment in an N_2 atmosphere. Formation of Ge_(1-x)Sn_x crystals, however, takes place during oxidation of SiGeSn alloys. The Ge_(1-x)Sn_x crystals are of nanometer size and of lens-like or sphere-like facetted shape. The formation of Ge_(1-x)Sn_x crystals takes place as a result of Sn and Ge segregation at the moving SiO_2/Si interface.