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In this study, we design and simulate a metal implanted dielectrically modulated tunneling field-effect transistor (MI-DMTFET). In the ambipolar conduction state, the proposed structure works as an efficient sensor for the detection of a wide range of biomolecules. A metal strip (MS) is implanted above the drain-channel junction in the gate dielectric to improve the alignment of band gaps. Therefore, with the help of implanted metal work function engineering, the tunneling barrier gets lowered, which in turn increases the ambipolar current. An optimum metal-strip implant work function of 4.85 eV and a length of 1.5 nm have resulted in significantly improved performance of the proposed device. It has been observed that when the biomolecules with varying dielectric constants and charge densities are captured in the nanogap cavity, the ambipolar current of the biosensor changes, resulting in the detection of the biomolecules. Quantitative and comprehensive analyses of device parameters such as surface potential, electric field, band-to-band tunneling, subthreshold slope, and I ON / I OFF ratio analysis have been performed. Rigorous comparative analyses of key performance-measuring parameters have been performed with a conventional sensor device. It has been found that the proposed device offers maximum sensitivity of 1220 under an ambipolar state at k = 12.

In this work, we propose and simulate an ultrasensitive, label-free, and charge/dielectric modulated Si:HfO 2 ferroelectric junctionless tunnel field effect transistor (FE-JL-TFET) based biosensor. The proposed sensing device employs a dual inverted-T cavity and uses ferroelectric gate stacking of Si-doped HfO 2 , a key enabler of negative capacitance (NC) behavior. The two cavities are carved in gate-source underlap regions by a sacrificial etching technique to sense biomolecules such as streptavidin (2.1), bacteriophage T7 (6.3) and gelatin (12). Two dimensional (2D) calibrated simulations have been performed and the impact of various device parameters, including cavity length and height, on various performance measuring parameters has been studied. It has been observed that the biosensor exhibits better sensitivities for both neutral and charged biomolecules. The maximum values of the I ON / I OFF sensitivity for the neutral, positively charged and negatively charged biomolecules are as high as 3.77 × 10 9 , 5.85 × 10 9 , and 1.72 × 10 10 , respectively. It has been observed that optimizing the cavity length and height can significantly improve the sensing capability of the proposed device. The comparative analysis of the proposed biosensor and other state of the art biosensors shows a significant improvement in the sensitivity (10 1 to 10 6 times) in the proposed biosensor. The detrimental effect of interface trapped charges on the biosensor performance is also analyzed in detail., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this work, design and calibrated simulation of carbon nanotube field effect transistor (CNTFET)-based cascode operational transconductance amplifiers (COTA) have been performed. Three structures of CNTFET-based COTAs have been designed using HSPICE and have been compared with the conventional CMOS-based COTAs. The proposed COTAs include one using pure CNTFETs and two others that employ CNTFETs, as well as the conventional MOSFETs. The simulation study has revealed that the CNTFET-based COTAs have significantly outperformed the conventional MOSFET-based COTAs. A significant increase in dc gain, output resistance and slew rate of 81.4%, 25% and 13.2%, respectively, have been achieved in the proposed pure CNT-based COTA in comparison to the conventional CMOS-based COTA. The power consumption in the pure CNT-COTA is 324 times less in comparison to the conventional CMOS-COTA. Further, the phase margin (PM), gain margin (GM), common mode and power supply rejection ratios have been significantly increased in the proposed CNT-based COTAs in comparison to the conventional CMOS-based COTAs. Furthermore, to see the advantage of cascoding, the proposed CNT-based cascode OTAs have been compared with the CNT-based OTAs. It has been observed that by incorporating the concept of cascode in the CNTFET-based OTAs, significant increases in gain (12.5%) and output resistance (13.07%) have been achieved. The performance of the proposed COTAs has been further observed by changing the number of CNTs (N), CNT pitch (S) and CNT diameter (DCNT) in the CNTFETs used. It has been observed that the performance of the proposed COTAs can be significantly improved by using optimum values of N, S and DCNT.