Abstract
A comprehensive study of the drain current drift mechanism and hysteresis phenomena in fabricated p-channel junctionless ion-sensitive field-effect transistor (JL-ISFET) has been investigated for the first time. The current drift measurements have been performed through transient analysis of drain current, under different pH and liquid-gate bias (Vlg). Further, time-dependent gate-capacitance (CG) has also been analyzed to see the effect of hydroxyl ions (OH−) in the sensing film (Al2O3). The hysteresis has also been investigated for different pH loop (7 → 3 → 7 → 11 → 7 and 7 → 11 → 7 → 3 → 7) and times (960s, 1500s, and 1920s). It has been observed that the drift of JL-ISFET occurs because of chemical modification of the sensing film, due to OH−. The proposed device exhibits a threshold voltage sensitivity of 58.2 mV/pH that is near the Nernstian limit. Further, the hysteresis width and maximum drain current drift are measured as \(\sim \) 1.3 mV and 2.4 μ A (\(\sim \) 75%), respectively.
Highlights
Continuous growth in nano-fabrication technology results in extensive research on biosensors, capable of detecting tiny biological species such as protein, virus, DNA, enzyme, and antibodies [1, 2, 3, 4, 5]
We demonstrated the effect of channel width on threshold voltage and drain current sensitivity of p-channel junctionless ion-sensitive field-effect transistor (ISFET) (JL-ISFET), with threshold voltage sensitivity near to theoretical Nernstian limit [16]
To evaluate the sensing performance of p-channel JL-ISFET, the pH sensitivity measurement has been done through the shift in the threshold voltage of the device under different pH (3 to 11)
Summary
Continuous growth in nano-fabrication technology results in extensive research on biosensors, capable of detecting tiny biological species such as protein, virus, DNA, enzyme, and antibodies [1, 2, 3, 4, 5]. Field-effect transistor (FETs)-based ion-sensitive field-effect transistor (ISFET) have gained interest as a promising candidate to be used as a point-of-care device for sensing applications due to their advantages, including existing CMOS process compatibility, miniaturized sensor size, low power consumption, portability, real-time and label-free detection [7, 8, 9, 10].
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