Influence Of Air Annealing On The Structural, Morphology And Optical Properties Of ZnSe Thin Films By CW-CO2 Laser Evaporation

CW-CO2 laser evaporation was used to deposit ZnSe thin films onto glass microscope slides. The films prepared were annealed in air at annealing temperatures of 100, 200 and 300°C. The effect of annealing temperature on the surface morphology, crystal structure and optical properties was investigated. All samples were seen to have an homogeneous surface morphology. The as-deposited and low temperature annealed ZnSe films exhibited the cubic phase. As the annealing temperature increased, a hexagonal phase developed and at 300°C the ZnO phase began to appear. The average crystallite size of ZnSe films increased from 23.84 to 49.64 nm on annealing at 200°C. Dislocation density, strain in the film and film thickness decreased when the annealing temperature increased up to 200°C. The optical band-gap of the as-deposited film was 2.76 eV decreasing to about 2.70 eV at the 200°C anneal. The introduction of the ZnO phase at 300°C decreased crystallite size whereas it increased film strain. This