Performance Enhancement of Silicon-Based Sub-Terahertz Detector by Highly Localized Plasmonic Wave in Nano-Ring FET

A compact monolithic trantenna (
tran
sistor-an
tenna
) device is presented for a high-performance sub-THz wave detector using 28-nm CMOS foundry process. Based on a highly localized plasmonic wave in a silicon nano-ring field-effect transistor (FET), we obtained a total 535-fold photoresponse (
$\Delta {u}$
) enhancement in an on-chip measurement as compared with our previous works using the same asymmetry ratio (
$\eta _{a}= 30$
). The inner contact diameter (
${d} _{\textit {in}}$
) was scaled down from 8 to
$0.13 ~\mu \text{m}$
for the parasitic resistance limit case. By changing the ground source from inside to outside the nano-ring FET, we could generate different
$\Delta {u}$
polarities, which in turn reduced the junction leakage with improved
$|\Delta {u}|$
. From a fabricated nano-ring FET with the outer ring grounded source, we observed
$5\times $
of additional
$|\Delta {u}|$
enhancement followed by
$107\times $
with
${d} _{\textit {in}}$
scaling. In addition, based on the highly localized plasmonic wave nano-ring FET without any external gain, a record-high free-space responsivity of 12.4 kV/W and a reduced noise equivalent power of 1 pW/Hz
$^{0.5}$
were experimentally demonstrated under 0.12-THz radiation.