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.