EVIDENCE FOR ATOMIC H INSERTION INTO STRAINED SI-SI BONDS IN THE AMORPHOUS HYDROGENATED SILICON SUBSURFACE FROM IN-SITU INFRARED-SPECTROSCOPY

The reaction of atomic hydrogen with a growing amorphous hydrogenated silicon film plays a crucial role in determining the final material pr operties: hydrogen saturates dangling bonds in the film and thereby lo wers the defect density, and it is assumed that hydrogen ij inserted i nto strained bonds of the silicon network thereby reducing the local d isorder. The latter reaction can be inferred indirectly since the tota l hydrogen uptake exceeds the decrease in the defect density. This let ter presents the first diner experimental evidence from in situ infrar ed spectroscopy for the insertion of hydrogen into strained Si-Si bond s. This reaction becomes visible during the addition of atomic hydroge n to an as-grown film by the appearance of a characteristic SiH vibrat ional mode at 2033 cm(-1) indicating a different embedding Si matrix c ompared to the standard SiH bulk vibration at 2000 cm-1. (C) 1997 Amer ican Institute of Physics. [S0003-6951(97)00252-0].