INFLUENCE OF SUBSTRATES ON THE STRUCTURAL AND OPTICAL PROPERTIES OF CADMIUM, MAGNESIUM, ZINC OXIDE (CdMgZnO) THIN FILMS FOR OPTOELECTRONIC APPLICATIONS

Transparent conducting oxide thin films have wide applications in optoelectronic devices. However, indium tin oxide exhibits toxicity issues. CdMgZnO is a promising alternative due to its tunable bandgap. We investigate the effect of substrate on CdMgZnO thin film properties to evaluate their suitability in photovoltaics and light emitting diodes (LEDs). CdMgZnO thin films were deposited on glass, silicon and indium telluride oxide (ITO) substrates using RF sputtering. Thin film structural properties were analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). Optical characterization was performed using UV-Visible spectroscopy and surface morphology using AFM. All films showed hexagonal wurtzite structure with preferred (002) orientation. Largest grain size of 38.82 nm was observed for silicon substrate. Bandgap ranged from 3.19 eV - 3.47 eV, tunable for optoelectronic applications. Highest surface roughness of 16.43 nm was noted for glass substrate indicating potential light scattering. Optical transmission was highest (89.92) % for silicon substrate and lowest (77.1%) for ITO substrate films. The different substrates exhibit properties suitable for photovoltaics and transparent electrodes. Further analysis of electrical conductivity is warranted to fully improve these CdMgZnO thin films.