Chemical vapour deposition of Cu 2O and CuO from CuI and O 2 or N 2O

Abstract

Thin films of CuO and Cu 2O were deposited from CuI as the copper source and O 2 or N 2O as the oxygen source. If O 2 was used, both CuO and Cu 2O were obtained. Cu 2O was deposited at low O 2 partial pressures ( P o 2 < 0.2 Torr) in a long isothermal hot wall chemical vapour deposition (CVD) reactor ( T=500 °C). The CuO phase was obtained at a certain position in the CVD reactor and a sudden maximum in the deposition rate was then reached. The maximum was attributed to a change in the deposition mechanism upon the formation of CuO. When I 2 was added to the reaction gas mixture, the maximum disappeared and the deposition rate increased. The formation of CuO was also investigated thermodynamically. For higher [I 2]/[CuI] ratios, the CuO phase was stable, even at a low O 2 pressure. Cu 2O films were also deposited with N 2O as the oxygen source. At 650 °C and with an excess of CuI, the deposition rate was found to be controlled by the decomposition of N 2O. Above a linear gas flow velocity of 70 cm s −1, the deposition rate was constant, which indicated a surface-controlled process.