Search

Metal-semiconductor-metal (MSM) architectures are popular for achieving high-responsivity Ga2O3 solar-blind photodetectors (SBPDs), however, the hot-electron-induced internal photoemission (IPE) effect restricts their detecting performance. Herein, we demonstrate the rational design of an Al/Al2O3/Ga2O3 metal–insulator-semiconductor (MIS) SBPD that has merits of enhanced responsivity, suppressed sub-gap response and ultralow dark current based on the simulation results obtained using Lumerical software. For the cylindrical patterned detectors with Al/Al2O3/Ga2O3 MIS structures, the optimized dimensions of Al electrodes with a conformed ultra-thin (2 nm) Al2O3 layer support the surface plasmon polariton resonances at 250 nm, thus improving the photoresponsivity to 74 mA W−1. Furthermore, the sandwiched Al2O3 layer lifts the barrier for hot electrons in electrodes, which significantly suppresses the IPE-induced sub-gap photoresponse by more than 105 in magnitude with respect to the Al/Ga2O3 MSM counterpart. Optical and electrical field distributions are overlapped in cylindrically patterned MIS detectors, simultaneously improving the excitation and collection efficiencies of excess carriers and resulting in the 103-boosted rejection ratio. [ABSTRACT FROM AUTHOR]

The reverse-voltage dependence of a photocurrent in a Ni/ β -Ga _2 O _3 Schottky barrier diode was investigated under sub-bandgap monochromatic illumination with wavelengths ranging from 275 to 1200 nm. Under low reverse bias conditions, a photocurrent induced by internal photoemission was observed. However, under high reverse bias conditions, the photocurrent near the absorption edge increased significantly with reverse voltage, and the increase was more pronounced for wavelengths closer to the absorption edge. Numerical calculations based on direct optical absorption induced by the Franz–Keldysh (FK) effect showed excellent agreement with the experimental data.