Effect of [Cu]/[Cu+In] Molar Ratios on the Growth and Physical Properties of CuInS2 Nano-Particles using Nan-Vacuum Method

Abstract

APT2012 Symposium 2-5 July 2012, Singapore Effect of [Cu]/[Cu+In] molar ratios on the growth and physical properties of CuInS2 nano-particles using nan-vacuum method Lin-Ya, Yeh, Kong-Wei Cheng*,Wen-Chun Pan Department of Chemical & Material Engineering,Chang Gung University,Taoyuan, Taiwan, ROC Chung-Shan Institute of Science and Technology, Taoyaun, Taiwan, ROC *e-mail: kwcheng@mail.cgu.edu.tw Abstract In this study, CuInS2 nano-particles were prepared in an ultrasonic bath using the non-vacuum method. The X-ray diffraction (XRD) patterns of samples revealed that the samples are the tetragonal CuInS2 phase with a highly (112) preferential orientation. With an increase in [Cu]/[Cu+In] molar ratio in precursor solution, the XRD patterns of the samples indicates that the samples are tetragonal CuInS2 phase, except that the diffraction peaks were slightly shifted to higher angles. The [Cu]/[Cu+In] molar ratio of samples increased with an increase in [Cu]/[Cu+In] molar ratio in precursor solution. No apparent sulfur deficits were observed in samples using energy dispersive analysis of X-ray (EDAX). With [Cu]/[Cu+In] molar ratio in samples of greater than 0.50, the samples are p-type semiconductors while with [Cu]/[Cu+In] molar ratio in samples of less than 0.47, the samples are n-type semiconductors. CuInS2 samples with an average diameter of 20 nm were observed using transmission electron microscope (TEM). The direct energy band gaps of samples were in the ranges of 1.33-1.57 eV obtained using UV-vis-NIR spectrophotometer.