Highly c-axis oriented (Mg, Sn) co-doped ZnO thin films for optoelectronic applications

Abstract

In this paper, results on the microstructural, optical and electrical characteristics of the (Mg, Sn) co-doped ZnO films as a function of Mg, Sn dopant concentrations have been presented. All the films are highly oriented along the c-axis in the (0 0 2) plane, possessing a hexagonal wurtzite crystal structure of ZnO. Upon doping and codoping, the crystallite size is found to decrease. The root mean square (RMS) roughness is maximum for the undoped ZnO film and decreases upon doping and codoping. The field emission scanning electron micrographs reveal granular surface morphologies of the films. The undoped ZnO films' transmittance is minimal and improves upon doping and codoping with a maximum of ∼95% of transmittance for the Mg:Sn (1:1 at%) co-doped ZnO film in the wavelength range 420–550 nm and beyond 700 nm. The electrical conductivity of the film increases upon doping and codoping with a maximum of 1.38x102 (Ω-cm)−1 for the Mg:Sn (1:1 at%) co-doped ZnO film. It has been established that the Mg:Sn (1:1 at%) co-doped ZnO film is a potential candidate to be used as transparent conductive oxide for optoelectronic applications.