Effects of Substrates on Structural and Morphological Characteristics of Radio Frequency Sputtered ZnO Layers

Abstract

High quality Zinc Oxide nanostructures (ZONSs) with customized traits became demanding for diverse applications. Based on this fact, some ZONSs with varied layer thicknesses (100 to 400 nm) were deposited on three types of Si (plain, polished and etched) and borosilicate glass substrates using the radio frequency (RF) sputtering method. Asdeposited samples were characterized systematically using various techniques to determine the effects of the substrates on their structures and morphologies. The XRD analyses of the sample showed the formation of high quality nanocrystallites with varying sizes where the crystallinity was improved with the increase of layer thickness and change of substrates. The FESEM and AFM images exhibited the nucleation of dense nanocrystallites with some pores/voids with enhanced surface roughness. In addition, the EDX spectra displayed the presence of appropriate chemical elements in the ZONSs layers. Sample grown on the etched Si substrate at layer thickness of 300 nm was found to be optimum. The results for the etched Si were presented. It was demonstrated that by optimizing the RF sputtering parameters (power of 100 W, Argon flow of 10 sccm and pressure of 10-5 mb) the structural and morphological traits of the layered ZONSs can be tailored. The proposed ZONSs may be useful for various optoelectronic applications including the metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors fabrication.