A gas-sensor based on tunnel-field-effect-transistor (TFET) is proposed that leverages the unique current injection mechanism in the form of quantum-mechanical band-to-band tunneling to achieve substantially improved performance compared to conventional metal-oxide-semiconductor fieldeffect-transistors (MOSFETs) for detection of gas species under ambient conditions. While nonlocal phonon-assisted tunneling model is used for detailed device simulations, in order to provide better physical insights, analytical formula for sensitivity is derived for both metal as well as organic conducting polymer based sensing elements. Analytical derivations are also presented for capturing the effects of temperature on sensor performance. Combining the developed analytical and numerical models, intricate properties of the sensor such as gate bias dependence of sensitivity, relationship between the required work-function modulation and subthreshold swing, counter-intuitive increase in threshold voltage for MOSFETs and reduction in tunneling probability for TFETs with temperature are explained. It is shown that TFET gas-sensors can not only lead to more than 10 000Â increase in sensitivity but also provide design flexibility and immunity against screening of work-function modulation through non-specific gases as well as ensure stable operation under temperature variations. V C 2013 American Institute of Physics. [http://dx.

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The phenomenon of impact-ionization is proposed to be leveraged for a novel biosensor design scheme for highly efficient electrical detection of biological species. Apart from self-consistent numerical simulations, an analytical formalism is also presented to provide physical insight into the working mechanism and performance of the proposed sensor. It is shown that using the impactionization field-effect-transistor (IFET) based biosensor, it is possible to obtain an increase in sensitivity of around 4 orders of magnitude at low biomolecule concentration and around 6 orders of magnitude at high biomolecule concentration compared to that in conventional FET (CFET) biosensors. Moreover, IFET biosensors can lead to significant reduction (around 2 orders of magnitude) in response time compared to CFET biosensors. V