Equilibration and stability in undoped amorphous silicon

The annealing of structure and defect density in silicon-implanted non-hydrogenated and hydrogenated amorphous silicon, a-Si and a-Si:H, is compared. In both materials, the annealing follows equilibrium-like trajectories of defect density versus Urbach energy. A comparison of implanted, as-grown, and light-soaked a-Si:H shows that these three materials are strained on an intermediate, extended, and local scale, respectively. Similar defect annealing rates in ion-implanted and light-soaked a-Si:H point to the same mechanism for relaxation, which most likely is associated with the diffusion of an atom or defect. Hydrogen is the most likely candidate, but more quantitative verification is needed.