Deposition of cupric oxide thin films by spin coating

Cupric oxide thin films were deposited onto soda lime glass by spin coating and subsequent annealing of copper nitrate dissolved in a glycerol–water solvent. It was found that the solution consistently gave reproducible films with good adhesion on glass. A range of band gaps were estimated between 0.8 and 1.17 eV, showing that this material has potential as a photoabsorber. Resistivity was successfully reduced from 1.47×105 to 7.02 Ω cm by doping the films with sodium. Dopant concentrations of 1 at-% gave the lowest resistivity, showing that the ideal doping is 1% or less. Film structure was found to improve with an increase in annealing time from 10 min to 1 h, although this did not have any noticeable effect on either the electrical or optical properties of the films.