Electronic-structure studies of hydrogenated amorphous silicon films

Abstract

We have made in situ photoemission measurements of $a-\mathrm{S}\mathrm{i}$ prepared by dc sputtering in a mixture of ${\mathrm{H}}_2$ and argon, and by reacting atomic hydrogen with sputtered films of $a-\mathrm{S}\mathrm{i}$. Differences in the hydrogen — silicon bonding orbitals and the shift of the valence-band edge are discussed. Annealing experiments are presented which show the changes in electronic structure associated with the different silicon — hydrogen complexes which evolve from the sample as the temperature is raised and the $a-\mathrm{S}\mathrm{i}$ is dehydrogenated. The dominant changes in the electronic structure are attributed to single Si — H bonds.