Improvement of photovoltaic properties of n-Cu2O/Au Schottky junctions

Development of Schottky junctions made with extremely cheap semiconductor material of electrodeposited cuprous oxide (Cu2O) is a viable approach for the low cost solar energy applications. In this study, Cu2O/Au Schottky junctions were investigated for this purpose. Two pre-treatment processes annealing in air at 175 °C for 15 min duration and sulphidation of film surfaces with ammonium sulphide vapour at 27 °C for 8 s duration were investigated. The study was also extended to combine pre-treatment of first annealing in air followed by sulphidation. Schottky junctions were fabricated by sputtering Au films of thickness ∼12 nm on pre-treated films. XRD, SEM, capacitance-voltage, current-voltage and photoresponse measurements were employed in the investigation. The unique pre-treatment process of combine annealing and sulphidation of n-Cu2O films resulted a Schottky junction capable of producing an increase in the built-in voltage from −197 mV to −943 mV at the interface and to record a high short circuit current density of 10.52 mA cm−2. In general, all the pre-treatment had a positive effect on the junction performance. Efficiency of the device is still at the low side (0.63%) due to poor fill factor and open circuit voltage. The study demonstrated that further optimization of pre-treatment processes and improvement of other structural parameters could produce an n-Cu2O/Au Schottky junction cable of producing conversion efficiency suitable for large scale solar energy applications.