Photoconductivity kinetics in AgIn5S8 thin films

The temperature (T) and illumination intensity (F) effects on the photoconductivity of as grown and heat-treated AgIn5S8 thin films has been investigated. At fixed illumination intensity, in the temperature region of 40–300 K, the photocurrent (Iph) of the films was observed to decrease with decreasing temperature. The Iph of the as grown sample behaved abnormally in the temperature region of 170–180 K. At fixed temperature and variable illumination intensity, the photocurrent of the as grown sample exhibited linear, sublinear and supralinear recombination mechanisms at 300 K and in the regions of 160–260 K and 25–130 K, respectively. This behavior is attributed to the exchange of role between the linear recombination at the surface near room temperature and trapping centers in the film which become dominant as temperature decreases. Annealing the sample at 350 K for 1 h improved the characteristic curves of Iph. The abnormality disappeared and the Iph − T dependence is systematic. The data analysis of which revealed two recombination centers located at 66 and 16 meV. In addition, the sublinear recombination mechanism disappeared and the heat-treated films exhibited supralinear recombination in most of the studied temperature range.

Research highlights▶ The photoconductivity kinetics of the AgIn5S8 thin films is investigated. ▶ The photocurrent of the as grown sample exhibited linear, sublinear, and supralinear recombination mechanisms at 300 K, above 160 K, and below 160 K, respectively. ▶ Annealing the sample at 350 K improved the characteristic curves of Iph. The data analysis of which revealed two recombination centers at 66 meV and 16 meV. ▶ The heat-treated films exhibited supra-linear recombination in most of the studied temperature range (40–300 K).