Abstract
The fabrication of new kesterite absorber layers has drawn tremendous attention among a number of researchers. This article reports the preparation of good-quality copper zinc germanium sulfide Cu2ZnGeS4 (CZGS(4)) thin films via a convenient spray pyrolysis method. The fabrication of an Al/n-Si/Cu2ZnGeS4/Au heterojunction is also presented. X-ray diffraction results confirmed the tetragonal structure in the CZGS(4) samples. Additionally, energy-dispersive x-ray examination illustrated that the Cu2ZnGeS4 samples possess a nearly stoichiometric composition. From the transmittance and reflectance data, the energy gap (E-g), refractive index (n) and absorption coefficient (alpha) were assessed. According to the Tauc relation, the Cu2ZnGeS4 thin samples exhibit a direct optical transition. The energy gap values were found to be in the range of 1.52-1.27 eV. The dispersion and nonlinear optical parameters of the Cu2ZnGeS4 samples were also investigated. Electrical studies showed that the Al/n-Si/Cu2ZnGeS4/Au heterojunction has good rectifying properties, with efficiency of 3.3%.