[论文解读] A New Compact Model For High-Performance Tunneling-Field Effect Transistors

Ramon B. Salazar, Hesameddin Ilatikhameneh+3 more|arXiv (Cornell University)|May 30, 2015

Advancements in Semiconductor Devices and Circuit Design被引用 4

一句话总结

本文提出了一种新型解析紧凑模型，用于高性能隧穿场效应晶体管（TFETs），通过建模沟道电势分布和带隙中的倏逝态，精确捕捉了完整的I-V特性，包括椭圆效应。该模型经全带原子级模拟验证，能够精确分析能量依赖的带间隧穿，并揭示了源/漏掺杂在缩放TFET中的关键作用。

ABSTRACT

A new analytic compact model is presented which describes the full current-voltage (I-V) characteristic of ballistic high-performance (aggressively scaled-down) tunneling field-effect-transistors (TFETs) based on direct-bandgap semiconductors. The model is based on an analytic description of two key features, which capture the main physical phenomena related to TFETs: 1) the potential profile along the channel including the impact of doping concentration in the source, and 2) the evanescent states in the bandgap region of the semiconductor including the ellipticity of the imaginary branch. The analytic description of the potential profile is made using two different approaches. One of them is based on a piecewise function derived from the Poisson's equation in the source and channel, and the other is an ad-hoc potential that describes accurately the tunneling distance. The compact model is validated by comparison with state-of-the-art quantum transport simulations using a full band atomistic approach. Both approaches proposed to describe the potential profile are found in good agreement with the data from the simulations in all regions of operation: the on/off states and both n/p branches of conduction. It is shown that as TFETs are scaled-down the impact of source/drain doping on device performance becomes crucially relevant. In addition, it is shown how this model can be used to calculate the energy-dependent band-to-band tunneling (BTBT) currents in TFETs, a feature that allows gaining deep insights into the underlying device physics. The simplicity and accuracy of the model provides a powerful tool to explore in a quantitatively manner how a wide variety of parameters (material-, size- and/or geometry-dependent) impact the TFET performance under any bias conditions.

研究动机与目标

• 开发一种紧凑模型，精确描述高度缩放TFET的完整电流-电压行为。
• 捕捉源/漏掺杂对TFET在亚阈值区和导通态下性能的影响。
• 提供沟道电势分布和带隙区域倏逝态的物理解释性解析描述。
• 实现对材料、尺寸和几何参数在所有偏置条件下对TFET性能影响的定量分析。
• 对能量依赖的带间隧穿电流进行建模，以深入理解器件物理。

提出的方法

• 该模型采用两种不同方法描述电势分布：一种基于源区和沟道区泊松方程的分段解。
• 第二种方法采用经验电势函数，精确表征沟道中的隧穿距离。
• 模型引入了带隙区域倏逝态虚部分支的椭圆性，这对精确预测隧穿电流至关重要。
• 通过将模型预测结果与最先进的全带原子级量子输运模拟结果对比，对紧凑模型进行验证。
• 该模型可实现能量依赖的带间隧穿（BTBT）电流计算，将物理参数与器件响应相联系。
• 该公式设计简洁而精确，可高效探索所有工作模式下各类器件参数。

实验结果

研究问题

• RQ1 如何利用包含源区/掺杂效应的解析表达式，精确建模高度缩放TFET沟道中的电势分布？
• RQ2 倏逝态的椭圆性对TFET隧穿电流有何影响？
• RQ3 源/漏掺杂如何影响高性能、高度缩放TFET的性能？
• RQ4 紧凑模型能否准确再现n型和p型导电分支在导通态和截止态下的I-V特性？
• RQ5 该模型在多大程度上可预测能量依赖的带间隧穿电流，以获得更深入的物理洞察？

主要发现

• 所提出的两种电势分布模型——基于泊松方程的分段模型与基于经验隧穿距离的模型——在所有工作区域均与全带原子级模拟结果高度一致。
• 该模型成功捕捉了TFET的完整I-V特性，包括导通态与截止态，以及n型和p型导电分支。
• 随着TFET尺寸进一步缩小，源区和漏区掺杂对器件性能的影响变得至关重要。
• 该模型可实现能量依赖的带间隧穿电流的精确计算，为分析隧穿过程的物理机制提供了有效途径。
• 紧凑模型兼具简洁性与高精度，是定量探索材料、尺寸和几何参数对TFET性能影响的强有力工具。
• 该模型在广泛偏置条件下得到验证，证实其鲁棒性与预测能力。