| dc.description.abstract |
Undoped and Zn-doped (3 atom%) β-Ga2O3 thin films are prepared by spray pyrolysis method on the c-plane sapphire and ITO substrate. Both the undoped and Zn-doped films show a homogeneous film surface witha uniform distribution of spherical grains. X-ray diffraction analysis reveals the formation of a monoclinic crystal structure for both the undoped and Zn-doped films. Elemental analyses confirm the presence of Ga, Zn, and O without any impurity and chemical analysis revealsthe highest oxidation states of Ga³⁺ and Zn²⁺.Comparison between the density function theory calculation and the photoelectron spectra of the valence band and core levels shows good consistency, with a small dispersion of Ga 3d levels. Zn doping in Ga2O3 reduceshole concentration and the optical band gap of this material.The undoped film exhibits ultraviolet luminescence (UVL) and blue luminescence (BL) respectively. The defect emission band of the undoped film becomes significantly broader with Zn doping, resulting in a green luminescence (GL) along with the UVL and BL. By using the sub-bandgap excitation energies below 4.1 eV, the relative intensities of UVL and BL bands in thedopedfilmcan be tuned; at 3.1 eV excitation energy these emissions can be switched off and the film exhibits only GL emission. Furthermore, the simulation of these emission bands of the Zn-dopedGa2O3 film within the framework of the configuration coordinate model reveals Zn-induced defect states and their electron-phonon coupling strength. The simulated results indicate that these UVL, BL, and GLcan be attributed to the self-trapped hole, VGa, and ZnGa acceptors, and their energy levels are found to be 0.6, 1.1, and 1.5 eV above the valence band maximum. |
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