Demonstration of high-responsivity epitaxial beta-Ga2O3/GaN metal-heterojunction-metal broadband UV-A/UV-C detector

We demonstrate epitaxial beta-Ga2O3/GaN-based vertical metal-heterojunction-metal (MHM) broadband UV-A/UV-C photodetectors with high responsivity (3.7A/W) at 256 and 365 nm, UV-to-visible rejection > 10(3), and a photo-to-dark current ratio of similar to 100. A small (large) conduction (valence) band offset at the heterojunction of pulsed laser deposition (PLD)-grown beta-Ga2O3 on metal organic chemical vapor deposition (MOCVD)-grown GaN-on-silicon with epitaxial registry, as confirmed by X-ray diffraction (XRD) azimuthal scanning, is exploited to realize detectors with an asymmetric photoresponse and is explained with one-dimensional (1D) band diagram simulations. The demonstrated novel vertical MHM detectors on silicon are fully scalable and promising for enabling focal plane arrays for broadband ultraviolet sensing. (C) 2018 The Japan Society of Applied Physics