Comparative Study of quaternary Mg and Group III element co-doped ZnO thin films with transparent conductive characteristics

Abstract

Mg and Ga co-doped ZnO (MgxGayZnzO, x+y+z=1, x= 0.05, y=0.02 and z= 0.93, MGZO), Mg and Al co-doped ZnO (MgxAlyZnzO, x + y + z = 1, x = 0.05, y = 0.02 and z = 0.93, MAZO), Mg and In co-doped ZnO (MgxInyZnzO, x+y+z=1, x= 0.05, y=0.02 and z= 0.93, MIZO), Mg doped ZnO (MgxZnyO, x+y=1, x =0.05 and y= 0.95,MZO) and pure ZnO thin films have been prepared on the glass substrates by RFmagnetron sputtering. Their structural, morphological, compositional, electrical, and optical properties were characterized. The X-ray diffraction patterns showed that all the thin filmswere grown as a hexagonal wurtzite phasewith c-axis preferred orientation without secondary phase. The (0002) peak positions ofMGZO, MAZO and MIZO thin films were not significantly changed. The cross-section field emission scanning electron microscopy images of MGZO, MAZO and MIZO thin films showed that all the thin films have a columnar structure with dense morphology. The MGZO thin film showed the best electrical characteristics in terms of the carrier concentration (3.7 × 1020/cm3), charge carrier mobility (8.39 cm2/Vs), and a lower resistivity (1.85 × 10−3 Ω cm). UV– visible spectroscopy studies showed that the MGZO, MAZO and MIZO thin films exhibit high transmittance over 85% in the visible region. The MGZO thin films showed wider optical band gap energy of 3.75 eV.