The formation of well-defined crystalline structures by UV laser   irradiation of amorphous silicon films
  This study provides a new insight into the processes which occur when thin film hydrogenated amorphous silicon is subjected to UV laser irradiation in the presence of oxygen. It achieves this by observing the effects of subjecting the films to progressively increasing laser radiation doses. This reveals that an array of nuclei is first created, leading to the formation of a well-defined crystalline network, consistent with the structure of silicon oxide. Further irradiation results in the formation of cone-like structures on the crystalline network, due to silicon-oxygen bond breakage and migration of the resultant silicon-rich material. Eventually the cone-like structures become the dominant features, but remain interconnected by nanowire remnants of the original crystalline structure. 
Saydulla K. Persheyev, James A. Cairns
cond-mat.mtrl-sci