Stable Cu2O Photoelectrodes by Reactive Ion Beam Sputter Deposition

Cu2O has been deposited on quartz substrates by reactive ion beam sputter deposition. Experimental results show that by controlling argon/oxygen flow rates, both n-type and p-type Cu2O samples can be achieved. The bandgap of n-type and p-type Cu2O were found to be 2.3 and 2.5 eV, respectively. The variable temperature photoluminescence study shows that the n-type conductivity is due to the presence of oxygen vacancy defects. Both samples show stable photocurrent response that photocurrent change of both samples after 1,000 seconds of operation is less than 5%. Carrier densities were found to be 1.90 × 1018 and 2.24 × 1016 cm−3 for n-type and p-type Cu2O, respectively. Fermi energies have been calculated, and simplified band structures are constructed. Our results show that Cu2O is a plausible candidate for both photoanodic and photocathodic electrode materials in photoelectrochemical application.