The preparation and characterization of Ga-doped CuInS₂ films with chemical bath deposition

Ga-doped CuInS₂ films were prepared on indiumtinoxide substrates by chemical-bath-deposition method. The XRD diffractograms demonstrate that CuInS₂ is the major crystalline phase of the as-prepared films. In addition, the doping density and flat band potential of the Ga-doped CuInS ₂ electrodes were measured with impedance spectroscopy based on the MottSchottky equation. With Ga molar ratios in the bath solution higher than 0.2, the semiconductor property of the sample was changed from n- to p-type. Additionally, the values of energy band gap and carrier densities of the Ga-doped samples were found in the range of 1.501.51 eV and 2.07×10 ¹⁵4.50×10¹⁵ cm^-3, respectively. Furthermore, the maximum photocurrent density of the as-prepared film was -1.28 mA/cm² (with an external potential set at -1.0 V) when subject to the illumination of a 300 Xe lamp. These visible-light responsive properties assure their promising applications in photo-absorbing layers for photovoltaic cells or photocatalysts for hydrogen production.