Structural and electrical characterization of Cu2ZnSnS4 ingot material grown by melting method

Abstract

Abstract In this work, a Cu2ZnSnS4 (CZTS) ingot is grown via a melting method, then cooled; the resulting molten stoichiometric mixture is sealed off in a quartz ampoule under vacuum. The CZTS powder chemical composition analyses are determined using energy dispersive spectroscopy, and revealing the slightly Cu-rich and Zn-poor character of the ingot. Powder X-ray diffraction analysis reveals a crystalline structure with a kesterite phase formation, and a preferred orientation of (112) plane. The lattice constants of the a- and c- axes, calculated based on the XRD analyses, are a = 5.40 Å and c = 10.84 Å. Based on Hall measurements at room temperature, we find that the crystal exhibits p-type conductivity, with a high concentration of 1018 cm–3, a resistivity of 1.7 Ω cm, and a mobility of 10.69 cm2V–1s–1. Activation energies are estimated based on an Arrhenius plot of conductivity versus 1/T, for a temperature range of 80–350 K, measuring 35 and 160 meV in low- and high-temperature regimes, respectively, which is attributed to complex defects (2CuZn+SnZn) and antisite defects (CuZn), respectively. The observed scattering mechanisms are attributed to ionized impurities and acoustic phonons at low and high temperatures, respectively. The extracted band-gap is 1.37 eV.