No abstract

Indium sulfide (In2S3) thin films were deposited on glass and sapphire substrates by physical co-evaporation of the elements. The deposition parameters were varied to optimize the structural properties of the thin films. The sample epitaxially grown on a-sapphire substrate shows the smoothest surface and the highest crystallinity. The optical absorption properties were found to be independent on the deposition parameters and substrate material. We found for In2S3 a weakly pronounced absorption onset at 1.7 eV and a strong one at 2.5 eV, which can be attributed to direct band–band transitions located at 2.1 and 2.7 eV, respectively. Electrical characterization reveals photovoltaic activity with p-ZnCo2O4/ n-In2S3 heterodiodes but low performance due to non-ideal heterojunction properties. We further find a strong, persistent photoconductivity, which manifests itself in a strong time-dependence of the dark resistivity after the samples were exposed to light.

Undoped and vanadium‐doped In2S3 is used to fabricate pin‐diodes. As p‐type semiconductor two materials are compared: nano crystalline NiO and amorphous zinc‐cobalt‐oxid (ZCO). n‐ZnO:Al (AZO) is used as electrode to In2S3. In2S3‐films are grown by co‐evaporation, NiO‐ and ZCO‐films by pulsed laser deposition (PLD) and ZnO:Al‐films by RF sputtering. The diodes exhibit high current rectification of up to 3 and 6 orders of magnitude at ±2 V for diodes with p‐NiO and p‐ZCO, respectively. Diodes with p‐type ZCO are used for solar cell analysis. Upon illumination both solar cell types with undoped and V‐doped In2S3 as absorber material show photovoltaic activity. We find open‐circuit voltages of up to 300 mV and short‐circuit current densities of up to 0.29 mA cm−2.