Growth and Electrical Properties of Epitaxial ZnO Films Prepared by Chemical Bath Deposition Using a Flow Reactor

Abstract

Deposition methods using aqueous solutions have been developed as cost-effective routes to form transparent ZnO semiconductor films. Chemical bath deposition (CBD) employing a solution of zinc nitrate and hexamethylenetetramine is one of the most popular methods to grow ZnO using aqueous solutions. However, the electrical properties of ZnO films grown by CBD have not been extensively studied. In this study, epitaxial ZnO films were prepared by CBD using a flow reactor under various deposition conditions, and the temperature and reactant concentrations required for the growth of a transparent ZnO film with a smooth surface were determined. The electrical properties of the transparent ZnO films were examined by resistivity and Hall effect measurements. The optimum flow rate of the reaction solution, leading to the fastest growth of ZnO, was also identified. The ZnO film grown at such flow rate exhibited the highest electrical mobility. The carrier concentration and mobility of the ZnO film grown under the optimized conditions were 1.2 × 10¹8 cm⁻³ and 21 cm² V⁻¹ s⁻¹, respectively.