Thin film deposition of Cu_2O and application for solar cells

摘要

Deposition conditions of cuprous oxide (Cu_2O) thin films on glass substrates and nitrogen doping into Cu_2O were studied by using reactive radio-frequency magnetron sputtering method. The effects of defect passivation by crown-ether cyanide treatment, which simply involves immersion in KCN solutions containing 18-crown-6 followed by rinse, were also studied. By the crown-ether cyanide treatment, the luminescence intensity due to the near-band-edge emission of Cu_2O at around 680 nm was enhanced, and the hole density was increased from 10~(16) to 10~(17) cm~(-3). Finally, polycrystalline p-Cu_2O-ZnO heterojunctions were grown for use in solar cells. Two deposition sequences were studied, ZnO deposited on Cu_2O and Cu_2O deposited on ZnO. It was found that the crystallographic orientation and current-voltage characteristics of the heterojunction were significantly influenced by the deposition sequence, both being far superior for the hetero-junction with structure Cu_2O on ZnO than for the inverse structure. We successfully obtained a photoresponse for the first time in the deposited thin film of Cu_2O/ZnO.