Tuning the responsivity of monoclinic (InxGa1-x)2O3 solar-blind photodetectors grown by metal organic chemical vapor deposition

We report on the fabrication and characterization of solar-blind photodetectors based on metal organic chemical vapor deposition grown polycrystalline monoclinic indium gallium oxide (InxGa1-x)(2)O-3 alloys on sapphire using N2O for oxidation. The effects of growth conditions on indium incorporation efficiency and oxygen vacancies of the (InxGa1-x)(2)O-3 alloy, photo-to-dark current ratio (PDR), gain and responsivity of the fabricated photodetectors were investigated. The optical bandgap of the films was found to decrease due to the indium incorporation (x = 20.3%, 17.7%, 10.6% for samples A, B, and C, respectively) into the lattice of gallium oxide. By increasing the indium content incorporated into the lattice of Ga2O3, we demonstrated solar-blind photodetectors whose peak responsivity increased from 0.79 A/W (Ga2O3) to 319.1 A/W, 66.1 A/W and 27.7 A/W for samples A, B and C, respectively at 5 V applied bias with the cut off wavelength below 280 nm. Increasing in content resulted in a higher concentration of oxygen vacancies in as-grown films. Increased oxygen vacancies as a result of the change in growth conditions lead to higher photoconductive gain, higher responsivities, and lower PDR, demonstrating a trade-off between responsivity and the PDR. To the best of our knowledge, the peak responsivity value reported in this work is the highest for (InxGa1-x)(2)O-3 based solar-blind photodetectors. Fast rise and fall times in the order of 100 ms have been measured for the photodetectors.