Structural, morphological, electrical, optical, and photoluminescence properties of spray-deposited ZnO thin film: effect of hydrochloric and acetic acids in the precursor

Abstract

In this study, ZnO thin films were spray-deposited onto the soda lime glass and the effect of the presence of hydrochloric acid (HCl) and acetic acid (HAc) in the precursor was investigated. Adding HAc resulted in the compact and crack-free morphology with no distinguishable grain. On the contrary, by adding HCl, the grains were formed on the surface. Adding both HAc and HCl led to the crystallite size enlargement (from 52 nm to 98 and 119 nm, respectively); however, the presence of hydrochloric was more effective. Although the presence of both acids resulted in the carrier concentration increase, by virtue of having the highest mobility value (2.09 cm2 V−1 s−1), the ZnO thin film derived from adding HAc exhibited the highest electrical conductivity value (8.33 Ω−1 cm−1). The photoluminescence study revealed that zinc interstitial defects were responsible for the large carrier concentration of the ZnO film deposited from the starting solution containing HAc, while oxygen vacancies were the dominant donor centers for the ZnO thin firm resulted from the presence of HCl.