Effect of substrate temperature on the optoelectronic properties of DC magnetron sputtered copper oxide films

TL;DR

This study investigates how substrate temperature during DC magnetron sputtering affects the structural, optical, and electrical properties of copper oxide thin films, revealing temperature-dependent changes in conductivity and band gap.

Contribution

It provides detailed analysis of the influence of deposition temperature on copper oxide film properties, highlighting the role of microstructure in optoelectronic behavior.

Findings

Sheet resistance decreases with higher deposition temperature.

Optical band gap increases from 2.20 eV to 2.35 eV with temperature.

Films are primarily Cu₂O with a critical absorption edge at 300 nm.

Abstract

Copper oxide thin films are deposited on quartz substrates by DC magnetron sputtering and the effect of deposition temperature on their optoelectronic properties is examined in detail. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) analysis, Raman spectroscopy, UV-Vis spectroscopy, and four-probe sheet resistance measurements are used to characterize the surface morphology, structural, optical, and electrical properties respectively. Deposition is carried out at room temperature and between 200 and 300 {\deg}C. XRD analysis indicates that the oxide formed is primarily Cu$_2$O and the absorption spectra show the films have a critical absorption edge at around 300 nm. The sheet resistance gradually decreases with increase in deposition temperature thereby increasing the conductivity of these thin films. Also observed is the increase in band gap from 2.20 eV for room temperature deposition to 2.35 eV at 300 {\deg}C. The optical band gap and the variation of sheet resistance with temperature shows that the microstructure plays a vital role in their behavior. These transformation characteristics are of huge technological importance having variety of applications including transparent solar cell fabrication.