Structural, Optical and Electrical Properties of CuIn 0.7 Ga 0.3 Se 2 Ingot Prepared by Direct Melting

CuIn0.7Ga0.3Se2 (CIGS) ingots were prepared by reaction of high-purity elements in stoichiometric proportions. The direct melting of elements was carried out using an original and low-cost process. The structural and morphological properties of the obtained material were investigated through x-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. To detect and identify the defect chemistry of the obtained crystal, we used cathodoluminescence measurements at different temperatures. Moreover, the electrical properties of the CIGS material have been deeply investigated in this work using impedance spectroscopy. The activation energy for the conduction process was estimated. The conductivity data were found to obey the universal law of Jonsher. AC conduction is attributed to the correlated barrier hopping model. In the Nyquist diagram, two microscopic contributions to the electrical conduction were well identified.