Abstract: CdTe thin films with different thicknesses are prepared on well-cleaned glass by hot wall vacuum deposition,and their structural and optical properties are measured.XRD results show that the films are polycrystalline with a typical cubic phase structure and preferred orientation of (111).The lattice constant is 0.649nm for a 17.87μm film,which matches the standard value well.The transmittance spectra and the reflection spectra are measured with a Cary 5000 double beam spectrometer from 200 to 1200nm,and both the absorption coefficient and the extinction coefficient as well as the refractive index are discussed in the intrinsic absorption region.A plot of (hνα)2 versus hν is used to determine the optical energy gap of the CdTe thin films.It is found that the optical energy gap decreases with the increase of film thickness,possibly due to a larger grain size.These results confirm that CdTe is a direct gap material with a high absorption coefficient in the intrinsic absorption region.

Key words: hot wall vacuum deposition, CdTe thin film, structural properties, optical properties