In-situ IR and mass spectroscopic study of theAl(CH3)2/Ha-Si:H reaction processes

The reaction of dimethylaluminumhydride (DMAH) with photochemically deposited hydrogenated amorphous silicon (a-Si:H) has been studied in-situ with polarization modulation IR and quadruple mass spectroscopy. Under UV illumination, IR absorption bands due to hydrogenated silicon species incorporated in the a-Si:H decrease in intensity upon exposure to DMAH at 323–593 K. Between 323 and 473 K, the bands due to SiH3 species completely disappear by the exposure of DMAH while those of SiH2 species remain nearly unchanged. The intensities of the SiH2 bands begin to decrease above 473 K. These spectral changes caused by DMAH exposure are observed only in the early stages with marked evolution of H2 and CH4. These results suggest that DMAH reacts with SiH3 species at the outermost surface of the a-Si:H.