Nanoclustering of hydrogen in ion-implanted and plasma-grown amorphous silicon

We report a systematic study of small-angle x-ray scattering and Raman spec troscopy on hydrogen-implanted amorphous silicon (a-Si) and standard device -quality plasma-grown a-Si:H, both having a hydrogen concentration of ii at . %. The modifications of short-range and medium-range structural order ind uced by annealing are investigated. We find that annealing causes the forma tion and growth of nanoscale H complexes in both materials. However, the vo lume content of the H nanoclusters is strongly influenced by the disorder i n the original structure, remaining smaller by a factor of 3 in the a-Si:H with respect to the H-implanted sample. We discuss qualitative resemblances and quantitative differences of the structural evolution of H-implanted a- Si and a-Si:H in terms of H solubility and defect structure in a-Si. In add ition, the study of a-Si implanted with H at different concentrations shows that the amount of H nanoclustering increases superlinearly with the conce ntration of H atoms exceeding solubility. [S0163-1829(98)00843-1].