Structural, optical, and gas sensing properties of CdSe thin films deposited by SILAR method

Today, the rapid change that occurs with the acceleration of research and studies in thin film materials creates new opportunities for the development of new processes, materials, and technologies. In this study, cadmium selenide (CdSe) thin films were deposited on the glass substrate by successive ionic layer adsorption and reaction (SILAR) method with 30, 40, and 50 deposition cycles. Structural, optical, electrical, and gas sensing properties of CdSe thin films were investigated as a function of the deposition cycle directly related to the thickness of samples. The transmission decreased from 13 to 5% from 30 to 50 cycles whereas increasing in absorbance from 0.6 to 1.2. Optical bandgap values were calculated as 1.83, 1.79, and 1.76 eV for 30 cycle, 40 cycle, and 50 cycle, respectively. From Raman analyses, CdSe thin films have two strong modes at 200 cm −1 for all films and 819, 838, and 872 cm −1 for 50CdSe, 40CdSe, and 30CdSe, respectively. CO 2 gas detection measurements from 10 to 50 ppm were made for all samples at room temperature. The responses of 10 ppm CO 2 gas sensing were calculated as 4%, 5%, and 7% for 30 cycle, 40 cycle, and 50 cycle at room temperature. It was seen that the best results were obtained with the 50 cycle thin film. The effect of deposition cycle was investigated on the structural, morphological, optical, and electrical properties of the films in detail.