OPTICAL PROPERTIES OF N-DOPED Cu₂O THIN FILMS DEPOSITED BY RF-MAGNETRON SPUTTERING Cu₂O TARGET

Abstract

N -doped Cu 2 O films were deposited on quartz substrates by reactive magnetron sputtering a Cu 2 O target. The optical constants and thicknesses of the films with different nitrogen partial pressure (NPP) were retrieved from transmittance data by an optical model which combines the Forouhi–Bloomer model with modified Drude model. The results show that when NPP increases from 0.0 to 0.033 Pa, the optical gap decreases from 2.14 to 1.95 eV. Additionally, an optical absorption process in the infrared region below the optical band gap was observed for N -doped Cu 2 O films, which was not found in the pure Cu 2 O film. This is because an intermediate band (IB) in the band gap results from nitrogen doping. It is believed that N -doped Cu 2 O film with suitable NPP could be used to enhance the energy conversion efficiency for photovoltaic cells.