Fabrication and Characterization of β-Phase (Ga<sub>1-x</sub>In<sub>x</sub>)<sub>2</sub>O<sub>3</sub> Alloy Films on C-Plane Sapphire Substrates by Chemical Solution Deposition for Application in Visibl

The objective of this research is to deposit β-Phase (Ga1-xInx)2O3 alloyed films on c-plane sapphire substrates via chemical solution deposition and utilize them for visible-blind UV photodetectors. An aqueous hydrochloric acid solution, containing a mixture of gallium chloride and indium chloride, was employed as the precursor solution. By increasing the indium composition ratio up to x = 0.21, the optical band gap was reduced from 4.88 eV to 4.50 eV. Au/Ni comb-shaped electrodes were formed on β-Ga2O3 and β-(Ga0.79In0.21)2O3 films to fabricate metal-semiconductor-metal-structured photodetectors. The former only responded to UV-C irradiation, whereas the latter responded to both UV-C and UV-B irradiation. The responsivity (R), detectivity (D*), and external quantum efficiency (EQE) of the UV-C radiation (λ = 255 nm) were compared. The latter photodetector exhibited significantly higher values of R = 2.4×103 A/W, D* = 2.7×1013 Jones, and EQE = 1.2×106 %. Notably, the values of R and EQE are approximately seven orders of magnitude higher than those of the former. This result is attributed to the fact that the alloying of Ga2O3 and In2O3 reduces both electrical resistivity and bandgap energy. Our findings demonstrate that (Ga1-xInx)2O3 alloyed films deposited by a non-vacuum process using an aqueous precursor solution are promising candidates for application in visible-blind UV photodetectors.