Analytical drift-current threshold voltage model of long-channel double-gate MOSFETs

作者:Shih Chun Hsing*; Wang Jhong Sheng
来源:Semiconductor Science and Technology, 2009, 24(10): 105012.
DOI:10.1088/0268-1242/24/10/105012

摘要

This paper presents a new, physical threshold voltage model to solve the ambiguity in determining the threshold voltage of double-gate (DG) MOSFETs. To avoid the difficulties of the conventional 2 Psi(B) model in nearly undoped DG MOSFETs, this study proposes to define the on-off switching based on the actual roles of the drift and diffusion components in the total drain current. The drift current strongly enhances beyond the threshold voltage, while the diffusion current plays a major role in the subthreshold. The threshold voltage is defined as the drift component that exceeds the diffusion counterpart. From the solutions of Poisson's equation, the drift and diffusion currents of DG MOSFETs are separately formulated to derive the analytical expressions of the threshold voltage and associated threshold current. This model provides a comprehensive description of the switching behavior of DG MOSFET devices, and offers a physical onset threshold current to determine the threshold voltage in practical extraction.