The effect of thickness on structural, optical, and electrical properties deposited ZnO thin films by PLD

Abstract

In this paper, the effect of film thickness on structural, electrical, and optical properties of ZnO thin films deposited by Pulsed laser Deposition (PLD) over a quartz substrate has been studied. In PLD the thickness of the deposited thin films varies from 200 nm to 300 nm by increasing the number of laser shots from 9000 shots to 12,000 shots respectively. Deposited thin films were studied by Grazing angle X-ray diffraction (Gi-XRD), Ultraviolet–Visible transmittance spectroscopy (UV–Vis), Lateral I-V measurements, Field emission scanning electron spectroscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Gi-XRD result shows that films deposited over quartz are poly-crystalline in nature and are oriented along (002), (102), and (103) planes. FESEM analysis shows that 300 nm thick film is distributed uniformly over the surface and 200 nm ZnO thin film is distributed mainly at the center. EDX results show the presence of Zn and O elements in both deposited thin films. I-V characteristics in the dark show Schottky contact with Vc 2.9 V and 1 V for 200 nm and 300 nm thin films respectively. The optical band gap of ZnO thin films intersects at the same photo energies for both thicknesses. Tauc’s plot of both films reveals the similar optical band gap energies of 3.25 eV in both deposited films.