Physical properties of metal-doped ZnO thin films prepared by RF magnetron sputtering at room temperature

Abstract

Transparent thin films of pure ZnO, Ca-doped ZnO (CZO), and Ga-doped ZnO (GZO) were deposited on glass by RF magnetron sputtering. The influence of calcium and gallium concentrations in zinc oxide (ZnO) films on structural, morphology, electrical, and optical properties of thin films were studied. XRD results show that the obtained films were with a hexagonal wurtzite structure and preferentially oriented perpendicular to the substrate surface. Atomic force microscopy (AFM) evidenced that the type of doping modifies the microstructure of thin films. The as-deposited films show a high transmittance in the visible range over 85%. The shift of the optical band gap of ZnO films with increasing Ca and Ga content suggests the enhancement of carrier concentration. At Ga-doped ZnO, the film has lowest resistivity of 3.8 × 10−3 cm, while the carrier concentration is highest (2.2 × 1020 cm−3).