A novel band-to-band tunneling junctionless carbon nanotube field-effect transistor with lightly doped pocket: Proposal, assessment, and quantum transport analysis

Abstract

Overcoming the performance limits encountered with the conventional nanoscale transistors while simplifying the fabrication process is an objective that can give a new impulses to the modern nanoelectronics. A novel band-to-band tunneling junctionless carbon nanotube field-effect transistor, endowed with a lightly doped pocket underneath the coaxial gate, is computationally proposed herein. The quantum simulation based on the non-equilibrium Green's function formalism is used in the investigation while considering the self-consistent electrostatics and ballistic transport conditions. The proposed nanodevice switches via the modulation of band-to-band tunneling in the absence of thermionic emission mechanism. The pocket-induced barrier is employed to mitigate the ambiploar behavior attributed to the thermionic current and to improve the nanodevice performance. The simulations show that the proposed device exhibits improved leakage current, ambipolar behavior, subthermionic subthreshold swing, and current ratio in comparison to those provided by its conventional counterpart uniformly doped. In addition, the role of the pocket length in boosting the performance of the proposed band-to-band tunneling device is investigated, where the optimal length of lightly doped pocket is revealed. Note that the obtained enhancements have been thoroughly analyzed using the energy-position-resolved charge density and current spectrum. The recorded improvements, namely subthermionic subthreshold swing and high ION/IOFF current ratio, together with the merits of junctionless paradigm, make the proposed pocket-based technique, as an intriguing strategy that can be used to boost the performance of similar nanoscale band-to-band tunneling junctionless field-effect transistors for high-performance and low-power applications.