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 °C. 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.