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

Ga-doped CuInS2 films were prepared on indium-tin-oxide 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 CuInS2 electrodes were measured with impedance spectroscopy based on the Mott-Schottky 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 1.50-1.51 eV and 2.07 x 10(15)-4.50 x 10(15) cm(-3), respectively. Furthermore, the maximum photocurrent density of the as-prepared film was -1.28 mA/cm(2) (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. (C) 2010 Elsevier B.V. All rights reserved.