THERMAL-DESORPTION SPECTROSCOPY OF HYDROGEN FROM AMORPHOUS HYDROGENATED SILICON

Thermal desorption spectroscopy (TDS) based on the mass spectroscopy o f thermally evolved hydrogen is used for desorption analysis of amorph ous hydrogenated silicon (a-Si:FI). Two series of glow discharge chemi cal vapour deposited a-Si:H were investigated by the TDS method. Const ant temperature growth rate enabled to determine temperature regions o f hydrogen evolution and its total content in the film. These values a re compared with the results of infrared (IR) absorption spectroscopy. The dependence of the H content and the position of the maximum of th e evolution curve on deposition conditions, as radio frequency (RF) po wer used in a standard plasma enhanced chemical vapour deposition (PE CVD) glow discharge, was observed. The RF power was related to a silan e how rate during the deposition. The lower temperature of the evoluti on peaks and simultaneously the lower H content were observed in the l ayers prepared under the larger relative RF power conditions (the high silane decomposition efficiency). These results correlate well with l ight degradation measurements in device quality samples.