Characterization of functionally graded zinc oxide film prepared from aqueous solution by controlling cathode potential

Wurtzite zinc oxide (ZnO) film was cathodically deposited on a conductive g lass substrate from a simple aqueous zinc nitrate solution kept at 335 K. Z nO films with changing resistivity in the thickness direction was prepared at increased deposition rate by controlling potential method composed of Is t-step electrolysis at the cathode potentials ranging from -0.9 to -1.2 V r eferred to Ag/AgCl electrode for electric charge of 60 C m(-2) and of follo wing End-step electrolysis at -0.7 V up to 200 C m(-2). The sheet resistivi ty of the ZnO films decreased by about three orders of magnitude with the i ncrease in the film thickness from 0.3 to 0.9 mu m. Defect-free and 0.9 mu m-thick ZnO film with smooth surface was obtained by using controlling pote ntial method with Ist-step electrolysis of -1.2 V for approximately Ih and showed optical transmission of 74% at visible wave length.