Solar-blind UV detection by ultra-wide-bandgap 4HCB organic single crystal semiconductor

Abstract

In this work, the solar-blind ultraviolet (UV) detection performance of organic single crystals 4-hydroxycyanobenzene (4HCB) is demonstrated. The ultra-wide bandgap and low dark current make 4HCB an important candidate for this application. Detectors with two electrode configurations, i.e., sandwiched electrode (SWE) and interdigital electrode (IDE), are fabricated based on 4HCB single crystals and measured under the illumination of 254 nm-UV light. Apparently, the IDE detector exhibits a responsivity R of 14 000 μA W-1 at a bias voltage of 1000 V, which is 2000 times higher than that of the SWE detector, due to its enhanced photoconductive gain by the surface layer edge states. To explore the possibility for the space UV detection applications in the radiation environment, the effect of neutron radiation on 4HCB detector performance is revealed. The point defects introduced by fast neutrons, mainly H vacancies, dominate the variation of the Fermi energy level and electric properties; however, this effect on photodetection is limited when the neutron flux is below 1013 n cm-2.