Band Gap Tuning of DC Reactively Sputtered ZnON Thin Films

Abstract

Zinc oxynitride (ZnO$_x$N$_y$) has recently emerged as a highly promising band gap-tunable semiconductor material for optoelectronic applications. In this study, a novel DC reactive sputtering protocol was developed to fabricate ZnO$_x$N$_y$ films with varying elemental concentrations, by precisely controlling the working pressure. The band gap was rigorously analyzed using UV-Visible spectroscopy, which was complemented by EDAX spectroscopy to determine the variations in the elemental composition. The correlation between the microstructure and band gap was investigated through the application of AFM, XRD, and Raman spectroscopy, while the Urbach theorem was used to evaluate the defect states. This study revealed the existence of intermediate structures formed during the tuning of the band gap, which can have important implications for future research aimed at developing heterostructures and 2D superlattices for photonics applications.