Submicrostructural clusters and doping of amorphous silicon

Experiments on a-Si prepared by vapor deposition or ion bombardment exhibit anomalies which are most readily explained not by a continuous random network but by arrays of morphologically oriented paracrystalline clusters with 3% unreconstructed surface atoms. The effects of hydrogenation on the cluster dimensions are small compared to the effects of deposition or annealing temperature. Substantial morphological reorientation can be induced either by substrate-driven strain or by thermal annealing. Further experiments to study cluster morphological transitions are proposed.