Effects of Deposition Temperature on the Electrochemical Deposition of Zinc Oxide Thin Films from a Chloride Solution

Abstract

The structural, electrical, and optical properties of ZnO thin films electrochemically deposited from a chloride solution are investigated. We focus on deposition temperatures. The band gap energy decreased from 3.50 to 3.44 eV as deposition temperatures increased from 60 to 80°C. This variation of band gap is discussed with respect to both conduction and valence band shifts, and the Burstein-Moss effect caused by numerous carriers. Increase in the carrier density of ZnO thin films was observed with increasing deposition temperature; a markedly-high carrier density of 1 × 10²¹ cm⁻³ was exhibited. The origin of the carrier density was also investigated. Although the Cl⁻ content in ZnO thin films decreased with increasing deposition temperature, the increase of Cl⁻ acting as a donor was indicated.