【Device Papers】Photoelectronic properties and work function of ZnO:Ga films using Ga₂O₃ as gallium source

      Researchers from xxxx have published a dissertation titled " Photoelectronic properties and work function of ZnO:Ga films using Ga₂O₃ as gallium source " in Applied Surface Science.

Abstract

      Zinc oxide is one of the prominent materials for optoelectronic applications. The use of chemical or physical growth methods have a direct influence on its properties, which can be tailored by the incorporation of appropriate dopants. This work focuses on exploring the electrical properties of Ga doped ZnO films grown by rf sputtering, a physical vapor deposition technique, upon exposing the samples to photon excitation from a tungsten-halogen lamp. Experiments were performed under short and long period transient illumination conditions. The characteristic times during a light on/light off cycle were determined. The fastest respond was observed for the undoped films, an indication that the incorporation of Ga produced deep traps inside the band gap, which slowed the free carriers’ on/off photo response dynamics. In addition, the structural, optical and (in the dark) electrical properties were determined as a function of the Ga concentration and substrate temperature. Doping with Ga improved the conductivity of all samples. The films grown at 300 °C with 3 at.% presented the best conductivity. A correlation between the slope of the transmittance in the infrared and the free electron density, determined from Hall effect, was presented. Terahertz spectroscopy experiments probed deep levels in the ZnO band gap showing an inverse correlation between the electrical conductivity and IR absorbance in the energy range 0.11–0.99 eV. The work function was determined by Kelvin probe force microscopy, finding 4.46 eV for undoped ZnO, and a slight modification in the doped films, with 4.61 eV as the largest increment for films with 5 at.% Ga.

DOI：

https://doi.org/10.1016/j.apsusc.2026.167984