High Performance ZnSe-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors with Different Schottky Contacts

Abstract

We report on fabrication and characterization of high-performance ZnSe-based metal–semiconductor–metal (MSM) ultraviolet (UV) photodetectors with different Schottky contacts (Cr/Au, Ni/Au, Ag‑nanowire (Ag-NW)) and device structures (conventional planar contacts, interdigitated contacts, hybrid nanowire contacts). At room temperature, the low values of dark current of 0.71, 0.59, and 0.36 nA at bias voltage of 15 V were achieved for devices with Cr/Au, Ni/Au, and hybrid Ni/Au and Ag-NW contacts, respectively. A very high responsivity of 5.40 A W^–1 and detectivity of 3.4 × 10¹¹ cm W^–1 Hz^1/2 at bias voltage of 15 V for light with a wavelength of 325 nm is obtained for UV photodetector with Ni/Au interdigitated contacts. The best performance of devices with Ni/Au interdigitated contacts due to the higher Schottky barrier height of ~1.49 eV for Ni/Au contacts in comparison with ~1.26 eV for Cr/Au contacts is found. The measured response times of all UV photodetectors is in the µs-range and is limited by the RC time of the measurement system. Thus, this study demonstrates the high potential of ZnSe-based MSM structures with Ni/Au interdigitated and hybrid Ni/Au and Ag-NW contacts as a high-sensitive ultrafast UV photodetectors, which are promising for the applications, such as UV tomography and UV high-speed communication systems.