Ultrasensitive ZnO Nanowire Photodetectors with a Polymer Electret Interlayer for Minimizing Dark Current

Zinc oxide (ZnO) nanowires have attracted extensive interests in ultraviolet photodetection fields owing to their outstanding optoelectronic properties. The detectivity of ZnO nanowire photodetectors is often limited by large dark current due to a number of defect-induced carriers. Herein, a thin layer of poly(2-vinyl naphthalene) (PVN) is introduced between the ZnO nanowire and gate dielectric to deplete defect-induced carriers with the help of the electrostatic field generated by trapped electrons in the PVN layer. The dark current is successfully reduced from 2.2 x 10(-9) to 1.6 x 10(-14) A. Particularly, ZnO nanowire photodetectors with a large I-light/I-dark ratio (>10(7)), high photoresponsivity (>10(6) A W-1), and ultrahigh detectivity (>10(18) Jones) are achieved, which are among the best performance in reported ZnO-based photodetectors. The present simple scheme offers a new strategy to suppress dark current in semiconducting nanomaterials for ultrasensitive photodetection applications.