Hydrogen configurations and stability in amorphous sputtered silicon

The effects of the deposition parameters on configurations and stability of hydrogen (deuterium) in amorphous sputtered silicon a-Si:H have been analyzed using Fourier transformed infrared absorption spectroscopy, deuterium effusion experiments, and x-ray diffractometry. The ratio of monohydride bonds Si–H was calculated from the infrared absorption stretching mode spectrum. This ratio was increased when the substrate temperature was increased. The effusion results in a-Si:D, when deposited with a simple cathode, have shown the presence of clustered deuterium weak bonds in microvoids (400 °C deuterium effusion peak), beside isolated Si–D bonds embedded in the more compact tissue (650 °C deuterium effusion peak). The deconvolutions of the stretching mode infrared absorption spectrum of the as-grown sample and after isothermal annealing at 510 °C have allowed one to conclude that it is not possible to identify the low temperature and high temperature effusion peaks, respectively, with the decomposition of Si–H2 and Si–H centers. The effusion of the less stable hydrogen improved the amorphous structural relaxation. The ratio of monohydride bonds was increased by introducing a magnetron cathode in the deposition chamber. At the same time, the deuterium effusion spectrum was modified, showing a continuous deuterium effusion from 350 °C, instead of two well-defined effusion peaks.