Characterization of ZnO and Al doped ZnO thin films prepared by SILAR method

Abstract

The present work is conducted in two stages, first synthesizing ZnO and Al doped ZnO thin films on glass substrates by SILAR method and second, comparing their optical, structural and morphological information. 0.025 M Zinc ammoniac solutions were prepared using Zinc Chloride. In one sample solution Al doping was obtained by adding 1% Aluminum Chloride. At room temperature SILAR cycles of 50 dips were conducted separately for two samples and thus obtained samples were annealed at 450°C for two hours. Obtained ZnO film sample were marked as S1(Sample1) and AZO film as S2(Sample 2). Optical transmittance and absorbance of the prepared samples were revealed by investigating with UV- Visible spectrometer. The transmittance of S1 was comparatively greater to that of S2, were absorbance was vice versa, which gives direct information regarding the increase in crystallinity of S2. The peak and average values of the samples were recorded. From X-ray diffraction, enhancement of intensity peaks was observed in S2 which shows the crystalline property in S2 surface. The lattice parameters were determined from it and ZnO hexagonal structures were identified. The grain size of the samples were calculated and compared. The surface analyses of the samples were provided by Scanning electron Microscope (SEM). Sample S1 was found to be smooth and uniform with good surface morphology whereas S2 was found to be rough and non-uniform. The grain size found to be decreasing in sample S2 compared to S1. So from the study it is confirmed that the grain size will decrease with Al doping but its concentration must be limited to lower values and also SILAR is found to be an effective method in preparing ZnO and Al doped ZnO thin films.