Synthesis and characterization of pure and doped ZnO thin films by colloidal solution route

Abstract

newline ZnO, a II-VI group semiconductor having a direct wide band gap (3.37 eV) and large exciton binding energy (60 meV), has great attention of researchers because of its electrical and optical properties which makes it an important material in various applications. ZnO thin film exhibits hexagonal wurtzite crystal structure. High excitonic binding energy, high resistivity against radiation, high breakdown voltage, sensitivity to visible light, and easy wet chemical stability are some of the interesting features of this material. ZnO is mostly being deposited using two ways: vacuum deposition and chemical route. The main drawback of vacuum deposition is the requirement of expensive vacuum equipments. Additionally the throughput of this method is less compared to chemical (colloidal) one. The present work focuses the Chemical Bath Deposition (CBD) method due to its simplicity in requirements. Another advantage of the CBD method over other methods is that the film can be deposited on substrates of different shapes and size. Influence of multiple layering of pure ZnO thin films on the structural, morphological and optical properties are studied. The films of various thicknesses and particle size are prepared by varying the concentration of ZnCl2 as precursor material from 0.1M to 0.5M. Structural, morphological, optical and electrical properties of pure zinc oxide (ZnO) thin films grown by CBD and dip coating method on glass substrates and effect of doping various materials such as copper (Cu: ZnO), sodium (Na: ZnO) and potassium (K: ZnO) on the properties of ZnO thin films grown by CBD on glass substrates are investigated. newline