Carrier concentration of calcium zinc oxide with different calcium contents deposited through spray pyrolysis

Calcium zinc oxide (CaZnO) films were prepared via spray pyrolysis deposition at 300 °C with zinc acetate and calcium acetate precursors of various calcium/zinc atomic ratios (CZ) in an aqueous solution. The surface morphology and crystalline structure of the samples were analyzed via scanning electron microscopy and X-ray diffraction. The size of the film grain increased with the CZ parameter, and the films exhibited a zinc oxide structure with preferred (101) orientations. The Ca content and the optical bandgap increased with the CZ parameter as well. Hall measurements were carried out to determine the carrier concentration and mobility. All films showed n-type conduction, with concentrations ranging from 1.7 × 10¹⁶ to 8.7 × 10¹⁶ cm⁻³ for the unintentionally doped CaZnO films. The concentration showed an increasing—flat behavior, and the mobility showed flat—decreasing behavior with an increase in the CZ parameter. Different deep-level states were identified by analyzing the photoluminescence, and these states dominate the carrier concentration of the CaZnO films prepared via spray pyrolysis.