Optimum Functionalization of Si Nanowire FET for Electrical Detection of DNA Hybridization

In this work, we demonstrate a wafer-scale fabrication of biologically sensitive Si nanowire FET for pH sensing and electrical detection of deoxyribonucleic acid (DNA) hybridization. Based on conventional “top-down” CMOS compatible technology, our bioFETs explore a wide range of design (nanowires (NW), nanoribbons (NR), and honeycomb (HC) structures) with opening access scaled down to only 120 nm. After device fabrication, I
_DS
-V
_BG
transfer and I
_DS
-V
_DS
output characteristics show a conventional n-type FET behavior with an I
_ON
/I
_OFF
value higher than 10
⁵
, as well as an increase of threshold voltage as the NW width is reduced. Then, using a capacitive coupling in our dually-gated Si bioFETs, the pH sensitivity is enhanced with a pH response up to 600 mV/pH. Finally, we successfully detected an increase of threshold voltage of n-type silicon nanowires (SiNWs) due to hybridized target DNA molecules.