Characterization of Cu(InGa)Se2 (CIGS) thin films in solar cell devices

Abstract

Cu(InGa)Se2 (CIGS) thin-film solar cells are expected to be the next generation of solar cells because of their economical manufacturing cost and high yield process. In order to develop an efficient thin-film CIGS structure, however, a quantitative composition analysis of major elements is necessary. Quantitative analysis of CIGS was carried out by means of inductively coupled plasma-atomic emission spectrometry (ICP-AES), x-ray fluorescence, a wavelength-dispersed electron probe microanalysis (EPMA), and dynamic SIMS. The ratio of each element that comprises CIGS was determined by an ICP-AES analysis, which was performed by dissolving the entire CIGS sample. A reproducible and rapid semi-quantified analysis of CIGS can be conducted by using x-ray fluorescence and electron probe microanalysis and comparing the results to the certified composition of ICP-AES. Quantitative analysis data for CIGS were also obtained from SIMS depth profiling, and the relative sensitivity factor value was calculated by using the mole fraction of ICP-AES as a reference value for the composition. The atomic force microscopy results indicate that the reproducibility of the SIMS analysis was related to the surface roughness of the CIGS sample. Copyright (c) 2012 John Wiley & Sons, Ltd.