L-Shaped High Performance Schottky Barrier FET as Dielectrically Modulated Label Free Biosensor

In this work, we demonstrate the realization of L-Shaped Schottky Barrier FET as a biosensing device with improved sensitivity. The proposed device uses dual material gate with work functions of 4.2 eV (Al) and 4.8 eV (Cu) and Hafnium Oxide (HfO
₂
) as the gate dielectric. In order to detect the biomolecule, a nano-gap cavity is created in the vertical gate (Gate1) by etching out the oxide. The electrical characteristics of biomolecules such as dielectric constant and charge density modulate the Schottky Barrier width, which in turn, changes the drive current of the device. Various sensitivity parameters have been thoroughly investigated at
${\text{V}}_{DS} =\,\,\text{V}_{GS}=0.5\text{V}$
and a comparative analysis with the conventional device has been performed. The results so obtained reveal that
$\text{I}_{ \mathrm{\scriptscriptstyle ON}}$
sensitivity of the proposed device is much better for both neutral as well as charged biomolecules (maximum of 21x for neutral, at K = 12; 20x for charged biomolecules at
$\rho =-5\times 10$
¹⁰
cm
⁻²
, at K = 12). Besides this, the
$\text{I}_{ \mathrm{\scriptscriptstyle ON}}/\text{I}_{ \mathrm{\scriptscriptstyle OFF}}$
sensitivity, transconductance (
${\text{g}}_{m}$
) sensitivity and selectivity show similar improvements. Further, the proposed device shows better sensitivity performance at low as well as at higher temperatures as compared to the state-of-the-art biosensing devices.