Wafer-Scale Fabrication of Sub-10 nm TiO2-Ga2O3n-p Heterojunctions with Efficient Photocatalytic Activity by Atomic Layer Deposition

Wafer-scale, conformal, two-dimensional (2D) TiO2-Ga2O3 n-p heterostructures with a thickness of less than 10 nm were fabricated on the Si/SiO2 substrates by the atomic layer deposition (ALD) technique for the first time with subsequent post-deposition annealing at a temperature of 250 °C. The best deposition parameters were established. The structure and morphology of 2D TiO2-Ga2O3 n-p heterostructures were characterized by the scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), etc. 2D TiO2-Ga2O3 n-p heterostructures demonstrated efficient photocatalytic activity towards methyl orange (MO) degradation at the UV light (λ = 254 nm) irradiation. The improvement of TiO2-Ga2O3 n-p heterostructure capabilities is due to the development of the defects on Ga2O3-TiO2 interface, which were able to trap electrons faster. Graphical Abstract