An extensive study is presented to describe the impact of partial hybridization on the device electrostatics and on current of a silicon dielectric-modulated tunnel field effect transistor (DM-TFET). To gain insight into the various design considerations and factors influencing the sensitivity, both process-related issue such as cavity length variation and real-time issues related to biomolecules behavior such as partial hybridization, charge, and position of receptors/target molecules have been investigated through extensive numerical simulations. The results indicate that TFET-based sensor does not suffer from scaling issues and thus can help in miniaturization without compromising the sensitivity, unlike a nanogap-embedded DM-FET.

Comparative Analysis of Dielectric-Modulated FET and TFET-Based Biosensor

In this paper, an analytical model for a p-n-p-n tunnel field-effect transistor (TFET) working as a biosensor for label-free biomolecule detection purposes is developed and verified with device simulation results. The model provides a generalized solution for the device electrostatics and electrical characteristics of the p-n-p-n-TFET-based sensor and also incorporates the two important properties possessed by a biomolecule, i.e., its dielectric constant and charge. Furthermore, the sensitivity of the TFET-based biosensor has been compared with that of a conventional FET-based counterpart in terms of threshold voltage (Vth) shift, variation in the on-current (Ion) level, and Ion/Ioff ratio. It has been shown that the TFET-based sensor shows a large deviation in the current level, and thus, change in Ion can also be considered as a suitable sensing parameter. Moreover, the impacts of device parameters (channel thickness and cavity length), process variability, and process-induced damage on the sensitivity of the biosensor have also been discussed.

A Dielectric-Modulated Tunnel-FET-Based Biosensor for Label-Free Detection: Analytical Modeling Study and Sensitivity Analysis

To reduce the fabrication complexity and cost of the nanoscale devices, a charge-plasma concept is introduced for the first time to implement a dielectric-modulated junctionless tunnel field-effect transistor (DM-JLTFET) for biosensor label-free detection. The formation of p+ source and n+ drain regions in DM-JLTFET is done by the deposition of platinum (work function = 5.93 eV) and hafnium (work function = 3.9 eV) materials, respectively, over the silicon body. Furthermore, a nanogap cavity embedded within the gate dielectric is created by etching the portion of gate oxide layer toward the source end for sensing biomolecules. For this, the sensing capability of DM-JLTFET has been investigated in terms of variation in dielectric constant, charge density, length, and thickness of the cavity at different bias conditions. Finally, a comparative study between DM-JLTFET and MOSFET biosensor is investigated. The implementation of proposed device and all the simulations have been performed by using ATLAS device simulator.

A Charge-Plasma-Based Dielectric-Modulated Junctionless TFET for Biosensor Label-Free Detection

In this paper, a short-gate tunneling-field-effect-transistor (SG-TFET) structure has been investigated for the dielectrically modulated biosensing applications in comparison with a full-gate tunneling-field-effect-transistor structure of similar dimensions. This paper explores the underlying physics of these architectures and estimates their comparative sensing performance. The sensing performance has been evaluated for both the charged and charge-neutral biomolecules using extensive device-level simulation, and the effects of the biomolecule dielectric constant and charge density are also studied. In SG-TFET architecture, the reduction of the gate length enhances its drain control over the band-to-band tunneling process and this has been exploited for the detection, resulting to superior drain current sensitivity for biomolecule conjugation. The gate and drain biasing conditions show dominant impact on the sensitivity enhancement in the short-gate biosensors. Therefore, the gate and drain bias are identified as the effective design parameters for the efficiency optimization.

Comparative Performance Analysis of the Dielectrically Modulated Full- Gate and Short-Gate Tunnel FET-Based Biosensors

Substance use patterns are notorious for their ability to change over time. Both licit and illicit substance use cause serious public health problems and evidence for the same is now available in our country. National level prevalence has been calculated for many substances of abuse, but regional variations are quite evident. Rapid assessment surveys have facilitated the understanding of changing patterns of use. Substance use among women and children are increasing causes of concern. Preliminary neurobiological research has focused on identifying individuals at high risk for alcohol dependence. Clinical research in the area has focused primarily on alcohol and substance related comorbidity. There is disappointingly little research on pharmacological and psychosocial interventions. Course and outcome studies emphasize the need for better follow-up in this group. While lack of a comprehensive policy has been repeatedly highlighted and various suggestions made to address the range of problems caused by substance use, much remains to be done on the ground to prevent and address these problems. It is anticipated that substance related research publications in the Indian Journal of Psychiatry will increase following the journal having acquired an 'indexed' status.

Substance use and addiction research in India

In this letter, we propose a dielectric modulated double-gate tunnel field-effect transistor (DG-TFET)-based sensor for low power consumption label-free biomolecule detection applications. A nanogap-embedded FET-based biosensor has already been demonstrated experimentally, but a TFET-based biosensor has not been demonstrated earlier. Thus, a concept of TFET-based sensor is presented by analytical and simulation-based study. The results indicate better sensitivity toward two different effects (dielectric constant and charge of biomolecule) in comparison with a FET-based biosensor, and the additional advantages of CMOS compatibility, low leakage (low static power dissipation), and steep subthreshold slope make TFET an attractive alternative architecture for CMOS-based sensor applications.

Dielectric Modulated Tunnel Field-Effect Transistor—A Biomolecule Sensor

Investigation of dielectric modulated (DM) double gate (DG) junctionless MOSFETs for application as a biosensors

In the present work, comprehensive investigation of the ambipolar characteristics of two silicon (Si) tunnel field-effect transistor (TFET) architectures (i.e. p-i-n and p-n-p-n) has been carried out. The impact of architectural modifications such as heterogeneous gate (HG) dielectric, gate drain underlap (GDU) and asymmetric source/drain doping on the ambipolar behavior is quantified in terms of physical parameters proposed for ambipolarity characterization. Moreover, the impact on the miller capacitance is also taken into consideration since ambipolarity is directly related to reliable logic circuit operation and miller capacitance is related to circuit performance.

Rakhi Narang

Papers

Comparative Analysis of Dielectric-Modulated FET and TFET-Based Biosensor

A Dielectric-Modulated Tunnel-FET-Based Biosensor for Label-Free Detection: Analytical Modeling Study and Sensitivity Analysis

Dielectric Modulated Tunnel Field-Effect Transistor—A Biomolecule Sensor

Investigation of dielectric modulated (DM) double gate (DG) junctionless MOSFETs for application as a biosensors

Assessment of Ambipolar Behavior of a Tunnel FET and Influence of Structural Modifications