In Situ Detection of Surface SiH n in Synchrotron‐Radiation‐Induced Chemical Vapor Deposition of a ‐Si on an SiO 2 Substrate

The sensitivity and linearity of infrared reflection absorption spectroscopy (IRAS) has been significantly improved by using a buried‐metal‐layer (BML) substrate having an SiO 2 (15 nm)/Al(200 nm)/Si(100) structure, instead of a plain Si(100) substrate. By applying this BML‐IRAS technique to the in situ observation of synchrotron‐radiation‐induced chemical vapor deposition of amorphous Si ( a ‐Si) on an SiO 2 surface using Si 2 H 6 gas, the vibrational spectra of surface SiH n species in this reaction system have been observed for the first time with sufficient sensitivity for submonolayer coverage. The main silicon hydride species after deposition at 423 K are surface SiH 2 and SiH. Surface SiH 3 and SiH 2 are observed to be easily decomposed by synchrotron radiation irradiation. The decomposition rate of SiH by synchrotron radiation irradiation is much slower than those of SiH 2 and SiH 3 .