Sputtering Growth of Nitrogen-doped Ga2O3 Films and Applications of Photodetectors

Thin-film Ga2O3-based solar- and visible-blind photodetectors (PDs) stand at the forefront of future applications, with their performance closely tied to film quality. Employing radio frequency magnetron sputtering, we deposited an intrinsic Ga2O3 thin film onto a double-throw (0001) sapphire substrate at a substrate temperature of 500 ℃ for 10 min. Subsequently, using the intrinsic Ga2O3 thin film as the substrate and maintaining constant process parameters, including background vacuum, working pressure, growth temperature, sputtering power, and duration, we introduced N2 at various flow rates (0, 5, 10, 15, 20, and 25 sccm) for the reactive sputtering growth of nitrogen-doped amorphous Ga2O3 thin films. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV–Vis spectrophotometry, and Hall effect measurements were utilized to probe the impact of N2 flow rate on the growth rate, surface morphology, elemental composition, crystallization quality, and optical characteristics, and electrical properties of the Ga2O3 thin films. With increasing N2 flow rate, the films exhibited a notable redshift of the absorption edge, accompanied by a decrease in optical band gap. Hall effect measurements confirmed the stable p-type conductivity of the nitrogen-doped Ga2O3 thin films. Subsequently, metal-semiconductor-metal-type PDs were fabricated using the nitrogen-doped Ga2O3 thin films. These PDs demonstrated heightened sensitivity to 365 nm near-UV light, boasting a remarkable response of 1.32 × 102 A/W and a high response speed of 0.028/0.17 s.