Effect of annealing on microstructure, residual stress, and photovoltaic characteristics of electrodeposited CdTe films

The effect of annealing on the characteristics of electrodeposited CdTe was investigated. As-deposited CdTe films showed a preferred orientation of ⟨111⟩ normal to the surface of the films. During the annealing, recrystallization and grain growth occurred and the crystallographic orientation became more random. Examination of relative intensity ratios of X-ray diffraction (XRD) peaks for samples annealed at different temperatures for different times showed that the orientation changed toward random up to a certain point before it started to move back toward the textured state. An Arrhenius analysis of the XRD intensity changes yielded an activation energy of 2.5 eV which matches well with that of Cd diffusion in CdTe suggesting that the reaction should be Cd diffusion-limited. The residual stresses in CdTe layers measured by XRD were on the order of 50 MPa which is much higher than the yield stress of CdTe indicating that the stress should introduce crystalline defects