Design and Growth of Quaternary Mg and Ga Codoped ZnO Thin Films with Transparent Conductive Characteristics

This study reports the design growth and characterization of quaternary Mg and Ga codoped ZnO (MGZO) thin films with transparent conductive characteristics deposited on glass substrates by RF magnetron sputtering. The effects of the Ga concentration (from 0 to 2 at %) on the structural, chemical, morphological, optical, and electrical properties of MGZO thin films were investigated. X-ray diffraction study showed that all the MGZO thin films were grown as a polycrystalline hexagonal wurtzite phase with a c-axis preferred orientation and random in-plane orientation. The 2θ value of the (0002) peak of MGZO thin films decreased with increasing Ga concentration. X-ray photoelectron spectroscopy confirmed the Mg and Ga binding energy peaks from the MGZO thin films. The MGZO thin films had a smoother surface morphology. The optical study showed that the band gap energy of MGZO thin films systematically increased from 3.25 to 3.75 eV with increase Ga concentration. The electrical resistivity of the MGZO thin films was improved from 9.5 × 10–2 to 6.89 × 10–4 Ω cm with increasing Ga concentration.