Ga2O3 metal–insulator-semiconductor solar-blind photodiodes with plasmon-enhanced responsivity and suppressed internal photoemission

Abstract Metal-semiconductor-metal (MSM) architectures are popular for achieving high-responsivity Ga 2 O 3 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/Al 2 O 3 /Ga 2 O 3 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/Al 2 O 3 /Ga 2 O 3 MIS structures, the optimized dimensions of Al electrodes with a conformed ultra-thin (2 nm) Al 2 O 3 layer support the surface plasmon polariton resonances at 250 nm, thus improving the photoresponsivity to 74 mA W −1 . Furthermore, the sandwiched Al 2 O 3 layer lifts the barrier for hot electrons in electrodes, which significantly suppresses the IPE-induced sub-gap photoresponse by more than 10 5 in magnitude with respect to the Al/Ga 2 O 3 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 10 3 -boosted rejection ratio.