A form of amorphous hydrogenated material with a low H content was deposited from a magnetically confined plasma, using a range of self bias voltages, and the structure was characterized in terms of its density, fraction of sp3 bonding, H content and H bonding. It was found that the Tauc optical gap varied from 2 to 3eV as the negative bias voltage was decreased. The density of paramagnetic centers ranged from less than 1018/cm3 to more than 1020/cm3. The photoluminescence properties of the films were correlated with the optical gap and defect density, and it was found that the photoluminescence and photoluminescence efficiency increased strongly with the optical gap.

S.R.P.Silva, J.Robertson, G.A.J.Amaratunga, J.Schwan: Philosophical Magazine B, 1996, 74[4], 369-86