Formation and Properties of Nanostructured Layers from Amorphous Silicon

摘要

Nanocrystalline silicon (nc-Si) films were prepared from hydrogenated amorphous silicon (a-Si:H) ones by using rapid thermal or conventional furnace annealing followed by stain etching in hydrofluoric acid solutions. The rapid thermal annealing at 950°C was found to result in partial or nearly complete crystallization of 0.5 μm thick a-Si:H films similarly to the annealing in furnace. The optical reflectance spectroscopy revealed the nc-Si formation as well the high optical quality of the formed nc-Si films. The Raman scattering spectroscopy allowed us to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 3-8 nm and 50- 90%, respectively, depending on the annealing regime. The PL measurements showed that, in contrast to the initial a-Si:H films and thermally annealed ones, the annealed films subjected to a short dipping in stain-etching solution exhibited efficient photoluminescence (PL) the spectral region of 600-900 nm at room temperature. The PL intensity and lifetime (20-50 us) of the stain-etched nc-Si films were similar to that for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to form inexpensive luminescent thin films for Si-based optoelectronics.