An Explicit Unified Drain Current Model for Silicon-Nanotube-Based Ultrathin Double Gate-All-Around <sc> mosfet</sc>s

Abstract

A unified drain current model for silicon-nanotube-based ultra-thin double gate-all-around (DGAA) mosfet is presented in this work. Physics-based, analytical expressions for surface potential and charge density are derived utilizing Fermi-Dirac statistic, one-dimensional density of states (DOS) and Gauss’ law in the ultrathin channel region of the device. Using the derived expressions of surface potential and charge density, a closed-form expression for the drain current under drift-diffusive transport regime is formulated within the purview of gradual channel approximation. The proposed drain current model takes account for two-dimensional carriers’ confinement, which becomes prominent in ultrathin channel devices. The derived model, which is valid for all regions of operation, provides a physics-based description of the surface potential, charge density, and drain current. Output and transfer characteristics of the proposed drain current model have been verified by comparing against results obtained from the three-dimensional numerical simulator for different device parameters. The performance of the proposed drain current model has been further validated with the data presented in reported results. The present drain current model is explicit, analytical, and does not employ any numerical schemes and thus can be readily used in the efficient exploration of any circuit design and simulations.