Molecular Hydrogen in Amorphous Silicon with High Internal Stress

Hydrogenated amorphous silicon with high compressive stress and hydrogen concentration as high as the hydrogen solubility limit has been studied. The concentrations of total hydrogen and bonded hydrogen have been determined by nuclear reaction analysis and infrared transmission spectroscopy, respectively. The amount of molecular hydrogen has been estimated as a difference between these two concentrations. Silicon ion implantation has been used to transform the hydrogen molecules into silicon-bonded hydrogen. The sensitivity of the Fourier transform infrared spectrometer to the expected variations in the bonded hydrogen concentration has been proved using hydrogen implantation. It has been concluded that in spite of high hydrogen content in the material the concentration of molecular hydrogen in the studied films is below 1 at. % and is not the reason for the high internal stress.