Band-Offset Engineering for GeSn-SiGeSn Hetero Tunnel FETs and the Role of Strain
In this paper a simulation study of the effect of conduction and valence band offsets on the subthreshold swing (SS) of a double-gate tunnel field-effect transistor (TFET) with gate-overlapped source is presented. The simulations show that if the pn-junction and the hetero-junction coincide, the ban...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2015-01-01
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| Series: | IEEE Journal of the Electron Devices Society |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/7006669/ |
| Summary: | In this paper a simulation study of the effect of conduction and valence band offsets on the subthreshold swing (SS) of a double-gate tunnel field-effect transistor (TFET) with gate-overlapped source is presented. The simulations show that if the pn-junction and the hetero-junction coincide, the band offsets can significantly improve the SS by suppressing the so-called point tunneling at the pn-junction. It turns out that the performance of an n-channel TFET is determined by the direct conduction band offset whereas that of a p-channel TFET is mainly effected by the energy difference between the light hole bands of the two materials. Thus, the performance of the hetero-junction TFET can be improved by selecting material systems with high conduction or valence band offsets. The misalignment between the pn-junction and the hetero-junction is shown to degrade the SS. The above-described band-offset engineering has been applied to the GeSn/SiGeSn hetero-structure system with and without strain. Simulations of GeSn/SiGeSn hetero-TFETs with band-to-band-tunneling parameters determined from pseudopotential calculations show that compressive strain in GeSn widens the design space for TFET application while tensile strain reduces it. |
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| ISSN: | 2168-6734 |