Bound exciton and optical properties of SnO₂ One-Dimensional nanostructures

One-dimensional nanostructures of direct-forbidden semiconductor SnO ₂ crystallite have been prepared in large scale via thermal evaporation of tin monoxide at 1100 °C. The anomalous optical emission even lasing phenomena are observed below the band edge under pulsed laser excitation, which usually does not occur for a direct-forbidden band semiconductor. Scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, UV-vis reflectance spectroscopy, and Raman scattering spectra were used to characterize the as-synthesized products. The processes of multiphonon coupling with exciton dominate in the exciton transition and lasing. The enhancement of exciton-phonon coupling and bound exciton transition could be mapped in the phonon scattering process. The origin of photoluminescence and lasing of SnO₂ nanobelts and nanowires was illustrated.