An Analytical Threshold Voltage Model for Triple-Material Cylindrical Gate-All-Around (TM-CGAA) MOSFETs

Abstract

In this paper, an analytical threshold voltage model is proposed for a triple-material cylindrical gate-all-around MOSFET considering parabolic approximation of the potential along the radial axis. The center (axial) and the surface potential models are obtained by solving the 2-D Poisson's equation in the cylindrical coordinate system. This paper refutes the estimation of the natural length using surface potential as in previous work and proposes the use of center-potential-based natural length formulation for an accurate subthreshold analysis. The developed center potential model is used further to formulate the threshold voltage model and also extract drain-induced barrier lowering (DIBL) from the same. The effects of the device parameters like the cylinder diameter, oxide thickness, gate length ratio, etc., on the threshold voltage and DIBL are also studied in this paper. The model is verified by the simulations obtained from 3D numerical device simulator Sentaurus from Synopsys. Index Terms-Center potential, drain induced barrier lowering (DIBL), hot carrier effect (HCE), short-channel effects (SCEs).

A 2-D analytical model for cylindrical gate tunnel FET (CG-TFET) based on center potential

“…The surface potential along the z-axis φ s (z) is related to the center potential φ c (z) as follows [24]:…”

“…All of the above discussed TFET models employ a 2-D analytical solution of the Poisson equation based on surface potential. However, Dubey et al [24] developed an analytical model for CG-MOS based on potential at the center of the cylindrical body. They reported that the characteristic length of the center potential model is smaller compared to the conventional surface potential-based model.…”

2D Analytical Modeling of Surface Potential for GaAs based Nanowire Gate All Around MOSFET

“…The Cylindrical Gate all around (CGAA) MOSFET architecture [5][6], the channel is surrounded by the gate so that the gate has more control over the channel which further minimizes the SCEs. Because of the shorter dimension and higher drive current, CGAA MOSFETs can achieve higher packing density as compared to double gate (DG) MOSFETs [7][8][9][10].…”

Analytical modeling of threshold voltage for Cylindrical Gate All Around (CGAA) MOSFET using center potential

“…In this paper, it has been observed that solving the center potential in the channel may produce more accurate results as compared to surface potential [12]. To solve the Poisson's equation, an assumption is made as the potential inside the channel has parabolic nature [13].…”