Multiscale Metrology and Optimization of Ultra-Scaled InAs Quantum Well FETs

TL;DR

This paper presents a multiscale simulation approach for ultra-scaled InAs quantum well FETs, providing design guidelines to improve device performance and reduce gate leakage.

Contribution

It introduces a comprehensive multiscale modeling methodology combining atomistic and quantum transport models for InAs QWFETs, validated against experimental data.

Findings

Good match with experimental I-V data for 30-50 nm devices

Identified gate contact geometry and work function as key parameters for gate leakage control

Higher gate work function can improve threshold voltage and suppress leakage

Abstract

A simulation methodology for ultra-scaled InAs quantum well field effect transistors (QWFETs) is presented and used to provide design guidelines and a path to improve device performance. A multiscale modeling approach is adopted, where strain is computed in an atomistic valence-force-field method, an atomistic sp3d5s* tight-binding model is used to compute channel effective masses, and a 2-D real-space effective mass based ballistic quantum transport model is employed to simulate three terminal current-voltage characteristics including gate leakage. The simulation methodology is first benchmarked against experimental I-V data obtained from devices with gate lengths ranging from 30 to 50 nm. A good quantitative match is obtained. The calibrated simulation methodology is subsequently applied to optimize the design of a 20 nm gate length device. Two critical parameters have been identified to control the gate leakage magnitude of the QWFETs, (i) the geometry of the gate contact (curved or square) and (ii) the gate metal work function. In addition to pushing the threshold voltage towards an enhancement mode operation, a higher gate metal work function can help suppress the gate leakage and allow for much aggressive insulator scaling.