Self-powered MSM deep-ultraviolet beta-Ga2O3 photodetector realized by an asymmetrical pair of Schottky contacts

Self-powered photodetectors working in solar-blind region (below 280 nm) have attracted growing attention due to their wide applicability. Monoclinic Ga2O3 (beta-Ga2O3) with excellent merits and a wide bandgap (4.9 eV) is regarded as a good candidate for solar-blind photodetector application. Self-powered photodetectors generally based on homo/heterojunction suffer from a complex fabrication process and slow photoresponse because of the interface defects and traps. Herein, we demonstrated a fabrication and characterization of a self-powered metal-semiconductor-metal (MSM) deep-ultraviolet (DUV) photodetector based on single crystal beta-Ga2O3 . The self-powered property was realized through a simple one-step deposition of an asymmetrical pair of Schottky interdigital contacts. The photocurrent and responsivity increase with the degenerating symmetrical contact. For the device with the most asymmetric interdigital contacts operated at 0 V bias, the maximum photocurrent reaches 2.7 nA. The responsivity R-lambda. external quantum efficiency EQE, detectivity D*, and linear dynamic range LDR are 1.28 mA/W, 0.63, 1.77 x 10(11) Jones, and 23.5 dB, respectively. The device exhibits excellent repeatability and stability at the same time. Besides, the device presents a fast response speed with a rise time of 0.03 s and a decay time of 0.08 s. All these results indicate a promising and simple method to fabricate a zero-powered DUV photodetector. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing AgreementFunding Agencies|Natural Science Foundation of China [51711530035, 61874084, 61704125]; Swedish Foundation for International Cooperation in Research and Higher Education (STINT) [CH2016-6722]