Bound Exciton and Optical Properties of SnO2 One-Dimensional Nanostructures

One-dimensional nanostructures of direct-forbidden semiconductor SnO2 crystallite have been prepared in large scale via thermal evaporation of tin monoxide at 1100 degrees 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.