| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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Phonon Limited Electron Mobility in Germanium FinFETs: Fin Direction Dependence |
| Ying Jing, Gen-Quan Han**, Yan Liu, Jin-Cheng Zhang, Yue Hao |
Key Laboratory of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071
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| Cite this article: |
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Ying Jing, Gen-Quan Han, Yan Liu et al 2019 Chin. Phys. Lett. 36 027301 |
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Abstract We investigate the phonon limited electron mobility in germanium (Ge) fin field-effect transistors (FinFETs) with fin rotating within (001), (110), and (111)-oriented wafers. The coupled Schrödinger–Poisson equations are solved self-consistently to calculate the electronic structures for the two-dimensional electron gas, and Fermi's golden rule is used to calculate the phonon scattering rate. It is concluded that the intra-valley acoustic phonon scattering is the dominant mechanism limiting the electron mobility in Ge FinFETs. The phonon limited electron motilities are influenced by wafer orientation, channel direction, fin thickness $W_{\rm fin}$, and inversion charge density $N_{\rm inv}$. With the fixed $W_{\rm fin}$, fin directions of $\langle 110\rangle$, $\langle 1\bar{1}2\rangle$ and $\langle \bar{1}10\rangle$ within (001), (110), and (111)-oriented wafers provide the maximum values of electron mobility. The optimized $W_{\rm fin}$ for mobility is also dependent on wafer orientation and channel direction. As $N_{\rm inv}$ increases, phonon limited mobility degrades, which is attributed to electron repopulation from a higher mobility valley to a lower mobility valley as $N_{\rm inv}$ increases.
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Received: 26 October 2018
Published: 22 January 2019
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| PACS: |
73.50.-h
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(Electronic transport phenomena in thin films)
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73.50.Bk
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(General theory, scattering mechanisms)
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73.50.Dn
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(Low-field transport and mobility; piezoresistance)
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| Fund: Supported by the National Natural Science Foundation of China under Grant Nos 61534004, 61604112 and 61622405. |
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