Direct Bandgap-like Strong Photoluminescence from Twisted Multilayer MoS2 Grown on SrTiO3,ACS Nano

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Direct Bandgap-like Strong Photoluminescence from Twisted Multilayer MoS2 Grown on SrTiO3
ACS Nano ( IF 15.8 ) Pub Date : 2020-12-07 , DOI: 10.1021/acsnano.0c04801
Soumya Sarkar ₁ , Sinu Mathew _{1,

2} , Sandhya Chintalapati ₃ , Ashutosh Rath ₄ , Majid Panahandeh-Fard ₁ , Surajit Saha _{1,

5} , Sreetosh Goswami _{1,

6} , Sherman Jun Rong Tan ₇ , Kian Ping Loh ₇ , Mary Scott ₈ , Thirumalai Venkatesan _{1,

6,

9,

10}

Affiliation

NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
Department of Physics, S.B College, Mahatma Gandhi University, Kerala 686101, India
Tata Institute for Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad, 500107, India
CSIR-Institute of Minerals and Materials Technology, Bhubaneshwar, Odisha 751013, India
Department of Physics, Indian Institute of Science Education and Research, Bhopal 462066, India
Department of Physics, National University of Singapore, Singapore 117542, Singapore
Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States
Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore

While direct bandgap monolayer 2D transition metal dichalcogenides (TMDs) have emerged as an important optoelectronic material due to strong light–matter interactions, their multilayer counterparts exhibit an indirect bandgap resulting in poor photon emission quantum yield. We report strong direct bandgap-like photoluminescence at ∼1.9 eV from multilayer MoS₂ grown on SrTiO₃, whose intensity is significantly higher than that observed in multilayer MoS₂/SiO₂. Using high-resolution electron microscopy we observe interlayer twist and >8% increase in the van der Waals gap, which leads to weaker interlayer coupling. This affects the evolution of the band structure in multilayer MoS₂ as probed by transient absorption spectroscopy, causing higher photo carrier recombination at the direct gap. Our results provide a platform that could enable multilayer TMDs for robust optical device applications.

中文翻译：

SrTiO _3上生长的扭曲多层MoS _2的直接带隙状强光致发光

虽然直接带隙单层2D过渡金属二硫化二氢（TMD）由于强的光-质相互作用而成为一种重要的光电材料，但它们的多层对应物却表现出间接带隙，导致光子发射量子产率差。我们报道了在SrTiO ₃上生长的多层MoS ₂在约1.9 eV处有很强的直接带隙状光致发光，其强度明显高于在多层MoS ₂ / SiO ₂中观察到的强度。使用高分辨率电子显微镜，我们观察到层间扭曲和范德华间隙增加8％以上，这导致层间耦合较弱。这影响了多层MoS _2中能带结构的演变如通过瞬态吸收光谱探测的那样，在直接间隙处引起更高的光载流子复合。我们的结果提供了一个平台，可以使多层TMD用于稳健的光学设备应用。

更新日期：2020-12-22

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