Combined experimental and DFT-TDDFT computational, structural and study effect of inter-diffusion Cu into CdTe thick film by annealing for optoelectronics

In the present study, thermal evaporation techniques were used to prepare Cadmium Telluride (CdTe) films with thickness 1 mu m on a glass substrate (at constant temperature150 degrees C). By immersing these films in a solution Cu(NO3)(2) (1g/1000ml) for 30 min, the prepared films were doped by ion exchange with Cu. Furthermore, the doped films were annealed in vacuum at different temperatures (25, 125, 250, 375, and 500 degrees C) for the diffusion of dopant Cu content, for 30 min. Using the method of Swanepoel, the film thickness as well as the refractive index of films was identified. The density functional theory (DFT-TDDFT) by DMol(3) was used for the optimization of CdTe and Cu:CdTe as an isolated molecule in the gaseous phase. From using the DMol(3)/(GGA-PW91) method with DFT-TDDFT simulation, the HOMO and LUMO values for CdTe and Cu:CdTe isolated molecule are 2.41 eV and 1.66 eV, respectively. The MEP computations and Quantum-chemical calculations properties are computed and combined with the experimental study by using DMol(3)/(GGA-PW91) software. The possible transition in these as deposited and treated films are found to allow direct transition with reduction of the band gap from 1.50 to 1.37 eV with an increase of the temperature of the annealing. Dielectric constant, Energy loss functions (VELF and SELF) for CdTe as deposited and treated were addressed in terms of temperature rise in the annealing. The energy gap is also determined using photoluminescence (PL) and its values the corresponding wavelength peaks correspond roughly to the energy obtained through optical studies. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, Cadmium Telluride (CdTe) films were prepared using thermal evaporation techniques, doped with Cu by ion exchange and annealed at different temperatures to optimize dopant diffusion. The thickness and optical properties of the films were identified using various computational methods, along with experimental studies. The energy gap of the films was determined through photoluminescence analysis, showing a direct transition with reduction of band gap upon annealing.