Thickness dependence of optoelectronic properties of gallium oxide film deposited by electron beam evaporation technique
摘要
In this study, the effects of β-Ga2O3 film thickness on morphological, topological, compositional, structural, optical, and optoelectronic properties were examined. The films were deposited onto sapphire and quartz substrates using electron beam evaporation. The surface roughness of the films was analyzed using atomic force microscopy, showing an increase from 2.70 nm to 5.03 nm as the film thickness increased. The grain size transitioned from sparse, tiny grains to a more uniform distribution of slightly larger grains, as revealed by field emission scanning electron microscopy. The presence of gallium and oxygen atoms was confirmed through energy-dispersive X-ray spectroscopy. The films showed β-Ga2O3 polycrystalline structures as confirmed by X-ray diffraction analysis. The inter-planar spacing and crystallite size increased from 6.67 to 10.74 nm as film thickness increased. In contrast, the energy band gap decreased from 5.12 eV to 4.87 eV. The optical density, skin depth, optical sheet resistance, and thermal emissivity were in the order of 0–3, 102 cm, 10–7 Ωm2, and 10–12, respectively. The study also revealed that the optoelectronic parameters such as optical density, refractive index, packing density, dispersive energy, single oscillator energy, charge carrier concentration, plasma frequency, relaxation time, optical conductivity and resistivity increased with the thickness of the films. In contrast, other parameters such as skin depth, absorption coefficient, extinction coefficient, band gap energy, porosity, lattice dielectric constant, optical sheet resistance, and thermal emissivity decreased as the film thickness increased.