CdTe nanostructures prepared by thermal annealing

Homogeneous thin films of a-CdTe:O were thermal annealed in an Ar flux. The as-grown samples have an amorphous structure. The annealed films crystallize to a mixture of both CdTe and CdTeO₃. For low annealing temperatures (less than 100°C) it is possible to get CdTe crystallites with sizes smaller than 14 nm. In this work we report measurements of x-ray diffraction and optical absorption spectra of these films. The x-ray diffraction patterns of the films were used to study the CdTe crystallization process as a function of the annealing temperature. The CdTe crystallite size of the films was determined from the diffraction patterns using the Debye-Scherrer formula. It was observed that the CdTe crystallite size increases with annealing temperature. The optical absorption spectra of the films with the smallest CdTe crystallite size show how the absorption band edge of CdTe is shifted by the effects of the crystallite size.