Effect of Deposition Temperature on the Properties of CdTe Thin Films Prepared by Close-Spaced Sublimation

CdTe films have been prepared by close-spaced sublimation under different conditions. When CdTe is deposited at a low temperature, grains with a single predominant growth plane (111) adhere to the substrate and gather into scattered particles. With increasing deposition temperature, the number of CdTe grains on the substrate increases very quickly, the grains begin to form a quasi-continuous film, and (220), (311), (400), and (331) growth planes of CdTe begin to appear. When the deposition temperature and time are increased further, the CdTe grains begin to accumulate, the pin-holes formed initially begin to disappear, and grain boundaries with traces of layer growth can be observed. Different transmittance of samples of different thickness is clearly apparent but changes of the band gap, E (g), of the CdTe films is negligible. XPS results suggest CdTeO3 is generated on the CdTe film surface as the deposition time is increased.