Atomic force microscopy images and the corresponding x-ray diffraction patterns of films grown under oxygen partial pressures of (a) , (b) , (c) , and (d) , with a copper nominal concentration of in all cases. -like hexagonal (wurtzite) phase; -like cubic (zincblende) phase.
Lattice parameter variation as a function of the nominal copper concentration obtained using the diffraction peaks for polycrystalline samples grown under and oxygen partial pressures.
Room temperature Raman spectra of films grown under the indicated oxygen partial pressures and copper nominal concentrations. (c) shows also the reduced Raman spectrum (dotted line) for the amorphous film.
Optical transmission spectra for various copper nominal concentrations of samples grown with oxygen partial pressures of (a) and (b) .
Band gap as a function of the nominal copper concentration for the different oxygen partial pressures used to grow the films. The inset shows the optical absorption coefficient as a function of energy.
Inverse temperature dependence of the resistivity [, where is a constant] of films grown with a nominal copper concentration of , under the indicated oxygen partial pressures.
Log of conductivity values at as a function of the activation energy for some typical amorphous semiconductors and for the amorphous film grown under and a nominal copper concentration of . For clarity purposes the usual chemical subindices have been labeled with numbers in parentheses.
Average chemical composition for films grown with nominal copper concentrations of 0.4, 1.0, and grown under the indicated oxygen partial pressures. The Cu concentrations were lower than .
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