FAST INTERFACIAL OXIDATION OF AMORPHOUS SI1-XGEX-H BY SNO2

Fast oxidation of amorphous (a) Si1-xGex:H by interfacial reaction with SnO2 was observed at the temperature range of 400-500 degrees C. The rate of interfacial oxidation was very significant, while a test in a dry O-2 ambient at the same temperatures showed no oxidation of a-Si1-xGex:H beyond the native oxide. The interfacial reaction of the a-SiGe:H/SnO2/glass system resulted in a layered structure of silicon oxide, tin oxide, and beta-Sn at the a-SiGe/SnO2 interface. The extent of the interfacial reaction was found to depend on the Ge content in the a-Si1-xGex:H films; after annealing, the resultant silicon oxide layer is thicker for the Si-rich SiGe layer than for the Ge-rich composition. On the other hand, the SnO2 layer was totally reduced by an a-Ge:H top layer after a 1 h, 500 degrees C annealing procedure. (C) 1995 American Institute of Physics.