Substrate bias influenced physical characteristics of nanocrystalline silver copper oxide films

Abstract

The silver-copper-oxide (Ag2 Cu2O3) films were prepared by reactive magnetron sputtering of equimolar silver copper alloy target (Ag50 Cu50) onto the glass substrates in an oxygen partial pressure of 2 X 10-2 Pa and at different substrate bias voltages in the range from 0 to -90 V. The X-ray photoelectron spectroscopic studies on the films formed at substrate bias voltage of -60 V showed the characteristic core level binding energies of Ag2Cu2O3. The films formed on unbiased substrates were X-ray amorphous. The mixed phase films of Ag2 Cu2O3 and Ag were deposited at substrate bias voltage of -30 V, where as nanocrystalline and single phase Ag2Cu2O3 films were achieved at substrate bias voltage of -60 V. The atomic force micrographs of the unbiased films showed spherical shaped grains while those deposited at higher substrate bias voltages exhibited grains with pyramidal shape. The electrical resistivity of the films increased from 1.2 X 10-5 to 8.6 X 10-3 Ωcm with increase of substrate bias voltage from 0 to -60 V respectively. The optical band gap of the films increased from 1.78 to 1.92 eV with increase of substrate bias voltage from 0 to -60 V.