Transparent conducting tin oxide thin films (thickness ~140 nm) have been synthesized by using vacuum evaporation technique under the vacuum of the order of 10-6 mbar at room temperature. These films have been deposited onto glass and single crystals of KCl substrates and subsequently annealed at different temperatures for varying time periods in high purity oxygen (99.999%) atmosphere to obtain single phase of tin oxide. X-ray diffraction measurements have been carried out on the films deposited onto glass substrates to reveal the phase formation of tin oxide. Secondary ion mass spectrometer (SIMS) and selected area electron diffraction pattern (SAEDP) measurements identify the presence of Sn, SnO and SnO2 phases in the films. Detailed XRD measurements and microstructural features recorded employing SEM, HRTEM, AFM and SIMS have been interpreted in the light of emission bands of these films occurred at 442 nm and 452 nm. The effect of vacuum conditions and annealing on nucleation and growth mechanism of tin oxide thin films has been presented and discussed in detail
