Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE

We report ultra-high responsivity of epitaxial [Formula: see text] (TGO) Schottky UV-C photodetectors and experimentally identified the source gain as deep-level defects, supported by first principles calculations. Epitaxial TGO films were grown plasma-assisted molecular beam epitaxy on (?201) oriented n-type ?-[Formula: substrates. Fabricated vertical devices exhibited peak responsivities high 3.5 A/W at ?5 V applied bias under 250 nm illumination with sharp cutoff shorter than 280 fast rise/fall time in milliseconds order. Hyperspectral imaging cathodoluminescence (CL) spectra examined to find mid-bandgap this gain. Irrespective different tin mole fractions, epilayer extra CL peaks green band (?2.20 eV) not seen along enhancement blue emission-band (?2.64 suppression UV emission-band. Based hybrid functional calculations optical emission expected for defects involving Sn text], Ga –Sn complexes are proposed potential defect origins observed emission-bands. Such behave acceptors that can efficiently trap photogenerated holes predicted be predominantly responsible photoconductive Sn-alloyed means thermionic electron tunneling. Regenerating optimizing growth techniques, we have demonstrated a planar photodetector highest responsivity.