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

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 ~ 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.