Enhanced carrier mobility and direct tunneling probability of biaxially strained Ge{sub 1−x}Sn{sub x} alloys for field-effect transistors applications

Journal Article · Thu May 14 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4921107· OSTI ID:22410185

Liu, Lei; Liang, Renrong; Wang, Jing; Xu, Jun ^[1]

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1. Tsinghua National Laboratory for Information Science and Technology, Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

The carrier transport and tunneling capabilities of biaxially strained Ge{sub 1−x}Sn{sub x} alloys with (001), (110), and (111) orientations were comprehensively investigated and compared. The electron band structures of biaxially strained Ge{sub 1−x}Sn{sub x} alloys were calculated by the nonlocal empirical pseudopotential method and the modified virtual crystal approximation was adopted in the calculation. The electron and hole effective masses at the band edges were extracted using a parabolic line fit. It is shown that the applied biaxial strain and the high Sn composition are both helpful for the reduction of carrier effective masses, which leads to the enhanced carrier mobility and the boosted direct band-to-band-tunneling probability. Furthermore, the strain induced valance band splitting reduces the hole interband scattering, and the splitting also results in the significantly enhanced direct tunneling rate along the out-of-plane direction compared with that along the in-plane direction. The biaxially strained (111) Ge{sub 1−x}Sn{sub x} alloys exhibit the smallest band gaps compared with (001) and (110) orientations, leading to the highest in-plane and out-of-plane direct tunneling probabilities. The small effective masses on (110) and (111) planes in some strained conditions also contribute to the enhanced carrier mobility and tunneling probability. Therefore, the biaxially strained (110) and (111) Ge{sub 1−x}Sn{sub x} alloys have the potential to outperform the corresponding (001) Ge{sub 1−x}Sn{sub x} devices. It is important to optimize the applied biaxial strain, the Sn composition, and the substrate orientation for the design of high performance Ge{sub 1−x}Sn{sub x} field-effect transistors.

• OSTI ID: 22410185
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
APPROXIMATIONS
CARRIER MOBILITY
COMPARATIVE EVALUATIONS
CONCENTRATION RATIO
CRYSTAL STRUCTURE
CRYSTALS
ELECTRONIC STRUCTURE
ELECTRONS
ENERGY GAP
FIELD EFFECT TRANSISTORS
GERMANIUM ALLOYS
HOLES
ORIENTATION
STRAINS
SUBSTRATES
TIN ALLOYS
TUNNEL EFFECT