Scrutinization of cobalt-doped CuGaS2 thin films prepared by spray pyrolysis method for photodetection applications

Abstract

Visible photodetectors are essentially utilized in optical communications and image sensing. CuGaS₂ is a ternary chalcopyrite system comprising greater absorption coefficient and direct bandgap is a suitable semiconductor for photodetector applications. Here, we present the preparation of pristine and Cobalt-doped CuGaS₂ (0.5, 1.0, 1.5 wt.%) thin film photodetectors using chemical spray pyrolysis method. Structural studies affirm the pure phase of CuGaS₂ and the incorporation of Cobalt dopants. Morphological studies confirm the presence of dopants on the CuGaS₂ lattice. Optical studies show the bandgap reduction due to Co doping which enhances photon absorption. The quick response under light illumination of the photodetectors is scrutinized by photoresponse studies at low power density of 4 mW/cm² and operation bias of 1 V. Responsivity and detectivity of pristine and Co-doped CuGaS₂ thin film photodetectors were determined and all devices show outstanding photoresponse in spite of having higher active area (1 cm²). Notably, the 1.0 wt.% Co-doped CuGaS₂ device show highest responsivity and detectivity of 2.40 µAW⁻¹ and 3.52 × 10⁷ Jones respectively despite having low operation bias and higher active area. The tuning of optical and electrical properties via doping resulted in this higher output. Therefore, Cobalt-doped CuGaS₂ thin films has great potential in advancing high performance photodetectors.