Thin-Film Single-Crystal Schottky Diodes for IR Detection and Beyond

Abstract

Thin-film p-type Co–Si and n-type Cr–Si Schottky diodes have been fabricated, in which a thin silicon layer is sandwiched between the anode and the cathode of the diodes, in a vertical configuration. The thicknesses of the silicon are 70 and 40 nm, for Co–Si and Cr–Si diodes, respectively. The thin layer significantly reduces the series resistance and the vertical structure reduces the parasitic capacitances in the diode, resulting in a high cutoff frequency, 100 and 54 THz, for the Co–Si and Cr–Si diodes, respectively. The dc current–voltage measurements show that the ideality factor is $\sim 1.25$ . The small ideality factor is attributed to the use of crystalline silicon, enabled by the transfer method. This leads to a relatively high theoretical estimation of responsivity of the diodes in nonlinear detection/rectification. The high cutoff frequency and high responsivity make these diodes a suitable candidate for terahertz (THz) detection, in the range of infrared (IR) and beyond. Our fabrication method and device structure allow for a better integration of Schottky diodes with a strip antenna, which provides a better mechanical stability for practical THz and IR applications.