Authors: WORAPOT SRIPIANEM, RATCHATEE TECHAPIESANCHAROENKIJ
Abstract: Codoping a semiconductor thin film with two or more dopants is a feasible technique to improve the electrical properties of the thin film. In this work, we studied the codoping of Al and Ga n-type impurities in a ZnO film (AGZO) deposited on a glass substrate by the spray pyrolysis method. The total doping concentration, [Al + Ga]/[Al + Ga + Zn], was 5 at.% with varying Al:Ga codoping proportions of 0:5, 1.25:3.75, 2.5:2.5, 3.75:1.25, and 5:0 at.%. The effect of Al/Ga codoping on the structural, texture, morphological, optical, and electrical properties of the AGZO films were investigated using X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscopy (SEM), UVvisible spectroscopy, and four-point probe technique, respectively. Varying Al:Ga codoping proportions significantly alter the textures and morphologies of the AGZO thin films. Thin films with higher Al doping content exhibit amorphouslike structures due to fine nano grains with high concentrations of disordered grain boundary regions. The optical transmittance spectrums show transmittance higher than 80% in the visible light region for all the codoped films. The sheet resistances and electrical resistivity of the AGZO films are significantly lower than those of the 5 at.% Al-doped ZnO films.
Keywords: Deposition, semiconductor, thin film, nanostructure, spray pyrolysis, doping
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