Effect of gallium proportion on the structural, optical, and electrical properties of the CuIn 1-x Ga x Se 2 compound

With their high absorption coefficient, the CuIn 1-x Ga x Se 2 chalcopyrite-structured compounds have a number of advantages in the race to produce large-scale, low-cost solar panels. In this perspective, CuIn 1-x Ga x Se 2 ingots ( x = 0.3, 0.4, 0.5) were prepared, and the influence of the proportion of gallium on the structural, optical, and electrical properties was studied. X-ray diffraction analyzes have shown that the obtained ingots are polycrystalline and possess a chalcopyrite structure. The preferred orientation along the plane (112) which is very suitable for photovoltaic conversion has been obtained. The main X-ray diffraction peaks showed changes in their diffraction angles that increased with increasing gallium proportion. The ratio “c/a” calculated from the lattice parameters “a,” and “c” was found close to two for all gallium proportions. Spectrophotometer analysis allowed us to observe the good absorption of the compound CuIn 1-x Ga x Se 2 , and the obtained results showed that the band gap width E g increases with the increase in the proportion of gallium and was found to vary between 1.12 eV and 1.32 eV, with E g = 1.26 eV for x = 0.4. Characterizations by Hall effect measurements showed that the produced ingots have a p-type conductivity. Also, a low resistivity of the order of 0.76 Ωcm was found for x = 0.4. The results obtained in the context of this work show that the prepared CuIn 0.6 Ga 0.4 Se 2 compound exhibits the best optoelectronic properties.