Light illumination effect on the electrical and photovoltaic properties ofIn6S7 crystals

Abstract

The electrical and photoelectrical properties ofIn6S7 crystals have been investigated in the temperature regions of 170–300 K and 150–300 K,respectively. The dark electrical analysis revealed the intrinsic type of conduction. The energyband gap obtained from the temperature-dependent dark current is found to be 0.75 eV. Itis observed that the photocurrent increases in the temperature range of 150 K up toTm = 230 K anddecreases at T>Tm. Two photoconductivity activation energies of 0.21 and 0.10 eVwere determined for the temperature ranges below and aboveTm, respectively. Thephotocurrent (Iph)–illumination intensity (F) dependence follows the law . The value of γ decreases when the temperature is raised toTm, then it starts increasing. The change in the valueγ with temperature is attributed to the exchange in role between the recombination andtrapping centres in the crystal. The crystals are found to exhibit photovoltaicproperties. The photovoltage is recorded as a function of illumination intensity at roomtemperature. The maximum open-circuit voltage and short-circuit photocurrent density,which are related to an illumination intensity equivalent to one sun, are 0.12 V and0.38 mA cm−2, respectively.