The n-type conduction of indium-doped Cu_2O thin films fabricated by direct current magnetron co-sputtering

摘要

Indium-doped Cu_2O thin films were fabricated on K9 glass substrates by direct current magnetron co-sputtering in an atmosphere of Ar and O_2. Metallic copper and indium disks were used as the targets. X-ray diffraction showed that the diffraction peaks could only be indexed to simple cubic Cu_2O, with no other phases detected. Indium atoms exist as In~(3+) in Cu_2O. Ultraviolet-visible spec-troscopy showed that the transmittance of the samples was relatively high and that indium doping increased the optical band gaps. The Hall effect measurement showed that the samples were n-type semiconductors at room temperature. The Seebeck effect test showed that the films were n-type semiconductors near or over room temperature (＜400K), changing to p-type at relatively high temperatures. The conduction by the samples in the temperature range of the n-type was due to thermal band conduction and the donor energy level was estimated to be 620.2-713.8 meV below the conduction band. The theoretical calculation showed that indium doping can raise the Fermi energy level of Cu_2O and, therefore, lead to n-type conduction.