Effect of disorder on the hydrogen content in Si

Hydrogen concentrations in disordered silicon were measured after exposure to a low-energy hydrogen rf discharge plasma at temperatures between 300 and 425 0C. The saturation hydrogen concentration is found to increase with disorder until amorphization is reached, whereupon the hydrogen content decreases. These results demonstrate that the amorphous structure cannot be considered as a simple extension of a highly defected crystalline structure. We further find that the hydrogen in a-Si exposed to atomic hydrogen in a plasma is bonded only in the monohydride site with an infrared absorption band at ν=1985 cm-1