Efficient visible luminescence of nanocrystalline silicon prepared from amorphous silicon films by thermal annealing and stain etching
1 Department of Physics, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia
2 al Farabi Kazakh National University, 96 Tole bi Str., Almaty 050000, Kazakhstan
Nanoscale Research Letters 2011, 6:349 doi:10.1186/1556-276X-6-349Published: 19 April 2011
Films of nanocrystalline silicon (nc-Si) were prepared from hydrogenated amorphous silicon (a-Si:H) by using rapid thermal annealing. The formed nc-Si films were subjected to stain etching in hydrofluoric acid solutions in order to passivate surfaces of nc-Si. The optical reflectance spectroscopy revealed the nc-Si formation as well as the high optical quality of the formed films. The Raman scattering spectroscopy was used to estimate the mean size and volume fraction of nc-Si in the annealed films, which were about 4 to 8 nm and 44 to 90%, respectively, depending on the annealing regime. In contrast to as-deposited a-Si:H films, the nc-Si films after stain etching exhibited efficient photoluminescence in the spectral range of 600 to 950 nm at room temperature. The photoluminescence intensity and lifetimes of the stain etched nc-Si films were similar to those for conventional porous Si formed by electrochemical etching. The obtained results indicate new possibilities to prepare luminescent thin films for Si-based optoelectronics.