TCAD models of the ballistic mobility in the source-to-drain tunneling regime
| Autor: | Paulina Aguirre, Andreas Schenk |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
010302 applied physics
Physics Gate length Thermionic emission Ranging 02 engineering and technology Solver Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Electronic Optical and Magnetic Materials Numerical integration Computational physics 0103 physical sciences Materials Chemistry Balance equation Electrical and Electronic Engineering 0210 nano-technology Quantum tunnelling Voltage |
| Zdroj: | Solid-State Electronics. 157:1-11 |
| ISSN: | 0038-1101 |
| DOI: | 10.1016/j.sse.2019.03.065 |
| Popis: | TCAD models of the ballistic mobility are developed where the mean ballistic velocity is not a fitting parameter, but a function of either the quasi-Fermi potential or the density. In the first case, a local version can be derived which is more robust when used together with a model for source-to-drain tunneling. The second form conserves the thermionic ballistic current and better matches the on-currents of short-channel FETs obtained from a quantum-transport solver, in particular at low source-drain bias. It requires the iterative extraction of the top-of-the-barrier density. This is the only non-local remnant of the hydrodynamic term in the balance equation for the mean velocity which is discarded in all commercial 2D/3D device simulators. The ballistic mobility, used with the Matthiessen rule, substitutes for this term and prevents that the drift-diffusion current diverges in the limit of zero gate length. The numerical integration of the models with the TCAD simulator S-Device is set out, and simulated transfer characteristics of In0.53Ga0.47As double-gate ultra-thin-body FETs with gate lengths ranging from 7 nm to 40 nm are compared with the corresponding quantum-transport results. It is shown that under conditions of dominant source-to-drain tunneling, the concepts of local quasi-Fermi potential and mean ballistic velocity break down. Suggestions for non-local modifications of both the mobility and tunneling models are given that would allow to use the same setup for all gate voltages from deep sub-threshold to deep inversion. |
| Databáze: | OpenAIRE |
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