Electrical Characterization and Sensitivity Analysis of Cavity-based Dielectric Modulated ZnO Nano-structured TFT for Biosensing Applications

A dielectric-modulated zinc-oxide nano-structured thin-film transistor (DM ZnO TFT) for biosensing applications is proposed in this work. This paper presents electrical characterization and sensitivity analysis of ZnO TFT biosensors with a cavity beneath the gate. Changes in device characteristics, such as transfer and output characteristics, have been observed by varying dielectric constant (K) of neutral biomolecules from 1 to 15. The maximum output drain current (I
DS
) of 56.19 mA/mm was obtained for a cavity filled with biomolecules with a higher dielectric constant (K = 15), which is
$3\times$
higher than the corresponding value of the device when the cavity is filled with the air
$(K=1)$
. The threshold voltage (V
th
) and maximum transconductance (gm) noted for (K = 15) are 47 mV and 11.86 mS/mm, whereas the corresponding values for (K = 1) are 636 mV and 4.35 mS/mm. The sensitivity parameters, such as relative threshold voltage sensitivity (Sv
TH
), transconductance sensitivity (Sg
m
), and output drain current sensitivity (S
IDs
) of the device, are also analyzed for different neutral biomolecules. The maximum Sv
TH
of 92.6%, Sgm of 209.1%, and S
IDS
of 172.6% are obtained for K = 15 with reference to K = 1, illustrating that the proposed device is highly sensitive for biomolecular detection.