Effect of post deposition heat treatment on microstructure parameters, optical constants and composition of thermally evaporated CdTe thin films

Abstract

Thin film microstructure and its properties can be effectively altered with post deposition heat treatments. In this respect, CdTe thin films were deposited on glass substrates at a substrate temperature of 200 °C using thermal evaporation technique, followed by air annealing at different temperatures from 200 to 500 °C. Structural analysis reveals that CdTe thin films have a cubic zincblend structure with two oxide phases related to CdTe 2 O 5 and CdTeO 3 at annealing temperature of 400 and 500 °C respectively. Regardless of the annealing temperature, the plane (111) was found to be the preferred orientation for all films. The crystallite size was observed to increase with annealing temperature. All films were found to display higher lattice parameters than the standard, and hence found to carry a compressive stress. Optical measurements suggest high uniformity of films both before and after post deposition heat treatment. Films annealed at 400 °C displayed superior optical properties due to its high refractive index, optical conductivity, relative density and low disorder. Furthermore, according to the compositional measurements, CdTe thin films were found to exhibit Te rich and Cd rich nature at regions near the substrate and center of the film respectively, for all annealing temperatures. However, composition of the regions near the substrate was found to become more Te rich with increasing annealing temperature. The study suggests that changing the annealing temperature as a post deposition treatment affects structural and optical properties of CdTe thin film as well as its composition. According to the observations, films annealed at 400 °C can be concluded to be the best films for photovoltaic applications due to its superior optical and structural properties.

Effect of deposition temperature on the growth mechanism of chemically prepared CZTGeS thin films

“…The pole density value was calculated from the following equation: where I i and I 0i are the intensities of the i th diffraction peak of deposited film and etalon from the reference data, respectively, and N is the number of lines on the radiograph. The orientation factor of the films was determined by the following equation: The Raman spectroscopy mapping analysis (RS‐mapping) was performed at a room temperature with the Renishaw InVia90V727 Raman microscope in backscattering geometry with excitation by a near‐infrared laser ( λ = 785 nm). The RS measurements were performed on a motorized table with the scanning area of 100 × 100 μm 2 .…”

“…where I i and I 0i are the intensities of the ith diffraction peak of deposited film and etalon from the reference data, respectively, and N is the number of lines on the radiograph. The orientation factor of the films was determined by the following equation 23,24 :…”

Structural, Optoelectrical, Linear, and Nonlinear Optical Characterizations of Dip-Synthesized Undoped ZnO and Group III Elements (B, Al, Ga, and In)-Doped ZnO Thin Films

“…The nonlinear optical parameters of thin films, such as third-order nonlinear susceptibility χ (3) and nonlinear refractive index n 2 , are crucial for the fabrication of several electronic and photonic devices [53,54]. The n 2 and χ (3) parameters are calculated by combining Miller's generalized rule and the parameters from the WDD single oscillator model [55][56][57] by utilizing the following formulas [58][59][60][61][62],…”

On the structural and thermophysical study of Pb-doped Se-Te-In nanochalcogenide alloys

“…In addition, it is observed that preferred orientation along (0 2 10) direction changes to (5 0 8) direction with Pb doping. The minimization in surface energy and internal stress might be dominating the occurrence of preferential orientation [47][48][49][50][51][52]. These observations reveal that growth direction of examined nanocrystalline composition changes with Pb amount.…”