High-Performance CNT-Based FETs on 200 mm Si Wafers With Low Drift and aM-Level Biosensing Sensitivity

Carbon nanotube (CNT)-based ion-sensitive FETs (ISFETs) and biosensor FETs (BioFETs) provide scalable solutions for liquid electrochemical sensing. We present fab-compatible CNT-ISFETs fabricated on 200 mm wafers and evaluated under electrolyte gating, showing consistent threshold voltage (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_th</i>) (0.45 ± 0.06) V, low gate leakage (10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> A), < 10% on-current drift over 7 h, and < 20% variation in key electrical parameters such as on-current, transconductance, threshold voltage, and subthreshold swing, demonstrating good deposition uniformity. After APTES functionalization, BioFETs exhibit <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_on/I_off</i> > 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup>, a narrow <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_th</i> (0.31 ± 0.02) V, and a subthreshold swing of (101 ± 4) mV/dec, meeting relevant performance criteria. Upon functionalization for DNA sensing, our BioFETs achieve responsivities of > 300% for 100 aM target DNA and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ΔV_th</i> ∼ 80 mV, marking the first instance of such low detection in label-free, non-nanoparticle-assisted CNT-FET biosensors.