Photoresponse enhancement of plasmonic terahertz wave detector based on asymmetric silicon MOSFETs with antenna integration

Abstract

We report the experiments of a plasmonic terahertz (THz) wave detector based on silicon (Si) field-effect transistors (FETs) in the nonresonant sub-THz (0.2 THz) regime. To investigate the effects of the overdamped charge asymmetry on responsivity (R-V), a FET structure with the asymmetric source and drain area under the gate has been proposed. RV as a function of gate voltage in Si FET-based detectors integrated with an antenna has been successfully enhanced by the asymmetry ratio (eta(a) = W-D/W-S) of gate-overlapped drain width (W-D) to source width (W-S) in agreement with the nonresonant quasi-plasma wave detection theory. The experimentally measured photoresponse has been enhanced by about 36.2 times on average from various samples according to the 10-fold increase in eta(a). The effect of the integrated bow-tie antenna on the performance enhancement has also been estimated as 60-fold at the maximum incident angle for the polarized THz wave source. (C) 2014 The Japan Society of Applied Physics