[Paper Review] A Predictive Compact Model for High-Performance Tunneling-Field Effect Transistors Approaching the Accuracy of NEGF Simulations

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

Advancements in Semiconductor Devices and Circuit Design3 citations

TL;DR

This paper presents a predictive compact model for high-performance tunneling FETs (TFETs) that accurately replicates NEGF simulation results by analytically modeling the source-to-channel potential profile and the elliptic curvature of complex bands in the bandgap. The model achieves high accuracy across all operating regions—on/off states and both n- and p-type conduction—while enabling efficient, physics-informed exploration of material, size, and geometry effects in ultra-scaled TFETs.

ABSTRACT

A new compact modeling approach is presented which describes the full current-voltage (I-V) characteristic of high-performance (aggressively scaled-down) tunneling field-effect-transistors (TFETs) based on homojunction 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 from source to channel, and 2) the elliptic curvature of the complex bands in the bandgap region. It is proposed to use 1D Poisson's equations in the source and the channel to describe the potential profile in homojunction TFETs. This allows to quantify the impact of source/drain doping on device performance, an aspect usually ignored in TFET modeling but highly relevant in ultra-scaled devices. The compact model is validated by comparison with state-of-the-art quantum transport simulations using a 3D full band atomistic approach based on Non-Equilibrium Green's Functions (NEGF). It is shown that the model reproduces with good accuracy the data obtained from the simulations in all regions of operation: the on/off states and the n/p branches of conduction. This approach allows calculation of energy-dependent band-toband tunneling currents in TFETs, a feature that allows gaining deep insights into the underlying device physics. The simplicity and accuracy of the approach provides a powerful tool to explore in a quantitatively manner how a wide variety of parameters (material-, size- and/or geometrydependent) impact the TFET performance under any bias conditions. The proposed model presents thus a practical complement to computationally expensive simulations such as the 3D NEGF approach.

Motivation & Objective

• To develop a compact model that accurately predicts the full I-V characteristics of aggressively scaled TFETs.
• To address the lack of systematic treatment of source/drain doping effects in existing TFET models, which is critical in ultra-scaled devices.
• To enable quantitative analysis of how material, size, and geometric parameters influence TFET performance under all bias conditions.
• To provide a computationally efficient alternative to expensive 3D NEGF simulations while retaining high physical fidelity.
• To capture energy-dependent band-to-band tunneling currents for deeper insight into TFET device physics.

Proposed method

• The model uses 1D Poisson's equation in the source and channel regions to analytically describe the potential profile in homojunction TFETs.
• It incorporates the elliptic curvature of complex bands in the bandgap region to model tunneling transport physics accurately.
• The approach enables calculation of energy-dependent tunneling currents, linking device geometry and material properties to current flow.
• The model is validated against 3D full-band atomistic NEGF simulations, ensuring high accuracy across all operation modes.
• It integrates doping profiles in source and drain regions to quantify their impact on performance, a feature often neglected in prior models.
• The framework supports systematic parameter sweeps across material, size, and geometry to explore performance trade-offs efficiently.

Experimental results

Research questions

• RQ1 How accurately can a compact model reproduce the full I-V characteristics of ultra-scaled TFETs compared to 3D NEGF simulations?
• RQ2 To what extent does including source/drain doping in the potential profile improve model accuracy and physical relevance?
• RQ3 Can the model capture both n- and p-type conduction branches with high fidelity across all bias conditions?
• RQ4 How does the elliptic curvature of complex bands influence tunneling current prediction in TFETs?
• RQ5 Can the model serve as a practical, fast alternative to computationally intensive NEGF simulations for device design and optimization?

Key findings

• The compact model reproduces NEGF simulation results with high accuracy across all operating regions, including on/off states and both n- and p-type conduction branches.
• The inclusion of source/drain doping in the 1D Poisson solution significantly improves the model's ability to predict device performance, especially in ultra-scaled geometries.
• The model successfully captures energy-dependent band-to-band tunneling currents, enabling deeper physical insight into tunneling mechanisms.
• The approach enables efficient, quantitative exploration of the impact of material, size, and geometry on TFET performance under any bias condition.
• The model achieves a balance between computational efficiency and physical accuracy, making it a practical alternative to 3D NEGF simulations.
• The model's predictive capability is validated across a wide range of device parameters, confirming its robustness and generalizability.