OPTICAL AND STRUCTURAL STUDIES OF NANOCRYSTALLINE SILICON THIN-FILM GROWN BY RAPID THERMAL ANNEALING

Optical and structural properties of nanocrystalline silicon (nc-Si) t hin film exhibiting blue-band photoluminescence (PL) at room temperatu re have been investigated, The nc-Si was grown by rapid thermal anneal ing at 800-1200 degrees C for 1-5 min in vacuum from amorphous Si. PL intensity is increased with the annealing time and temperatures, while PL peak energy of 2.5-2.7 eV is less sensitive. The nc-Si exhibits di stinguished properties such as little infrared absorption of Si-O mode or the average grain size of on the order of 10 nm from blue-band lig ht emitting nc-Si in literature. Thermoabsorption spectroscopy (TAS) s ignal, which monitors derivative of the optical absorption coefficient , sharply rises at 2.8 eV with small structures on 1200 degrees C anne aled nc-Si. The analysis of the TAS results implies that direct optica l transitions between quasi-three-dimensional bands are likely to be r esponsible for the blue-band emission.