Effect of the N2/O2 ratio on the morphology of SnO2 crystals synthesized through the thermal evaporation of Sn

SnO2 crystals were synthesized on sapphire substrate through the thermal evaporation of Sn powder in an oxygen and nitrogen gas environment at 1000 °C. No catalysts were used for the formation of the SnO2 crystals. One-dimensional structures such as wires and belts were formed in an N2 environment. With increasing the ratio of O2 to N2 in an ambient gas, the morphology of the SnO2 crystals changed from wire and belt to particle. This provides an evidence that the ratio of N2/O2 in the ambient gas is critical to the change in the morphology of SnO2 crystals. The X-ray diffraction analysis indicated that all the SnO2 crystals had a rutile tetragonal crystal structure. The cathodoluminescence spectra of the SnO2 crystals showed that N2/O2 ratio in the ambient gas had an influence on the emission properties.