Journal
ACS NANO
Volume 7, Issue 8, Pages 7126-7131Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn4024834
Keywords
MoS2; strain engineering; piezoelectric substrate; Raman spectroscopy; photoluminescence
Categories
Funding
- Research Grants Council of Hong Kong [PolyU 5006/12P]
- HK PolyU Grant [1-ZV8N]
- 973 Programs [2013CB932604, 2012CB933403]
- NSF of China [91023026]
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Tuning band energies of semiconductors through strain engineering can significantly enhance their electronic, photonic, and spintronic performances. Although low dimensional nanostructures are relatively flexible, the reported tunability of the band gap is within 100 meV per 1% strain. It is also challenging to control strains in atomically thin semiconductors precisely and monitor the optical, and phonon properties simultaneously. Here, we developed an electromechanical device that can apply biaxial compressive strain to trilayer MoS2 supported by a piezoelectric substrate and covered by a transparent graphene electrode. Photoluminescence and Raman characterizations show that the direct band gap can be blue-shifted for similar to 300 meV per 1% strain. First-principles investigations confirm the blue-shift of the direct band gap and reveal a higher tunability of the indirect band gap than the direct one. The exceptionally high strain tunability of the electronic structure in MoS2 promising a wide range of applications in functional nanodevices and the developed methodology should be generally applicable for two-dimensional semiconductors.
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