Investigation of gate-engineered heterostructure tunnel field effect transistor as a label-free biosensor: a compact study

In this article, the authors have articulated DC as well as transient response of a dielectric modulated gate-engineered heterostructure tunnel field effect transistor (GE-HTFET)-based biosensor for label-free detection. A low (direct) bandgap material, indium arsenide (InAs) has been selectively used in the source region to achieve improved band-to-band tunneling of carriers in the tunnel FET. The extended gate architecture is incorporated to stabilize the biomolecules in the nano-cavity aiding significant boost in ON current sensitivity. Using SILVACO ATLAS TCAD tool, the sensitivity of the biosensor is evaluated considering two important parameters possessed by bio-targets, i.e. dielectric constant (k) and charge density (N). A thorough analysis has been performed to show the impact of variation of dielectric constants and charge density of biomolecules over transfer characteristics of the device. ON current level (Ion) is eventually extracted which is considered here as the suitable sensing parameter of the device. Transient response to detect the settling time of Ion is also demonstrated here in presence of both positively and negatively charged bio-species with varying values of dielectric constant. Then ON current sensitivity is extracted accordingly for different locations of biomolecules within the nano-gap. Finally, an extensive comparative analysis of the present structure in terms of ON current sensitivity is shown to justify its sensing ability as compared to recently reported device structures.