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

Soumya Sarkar; Sinu Mathew; Sandhya Chintalapati; Ashutosh Rath; Majid Panahandeh-Fard; Surajit Saha; Sreetosh Goswami; Sherman Jun Rong Tan; Kian Ping Loh; Mary Scott; Thirumalai Venkatesan

doi:10.1021/acsnano.0c04801

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

ACS Nano. 2020 Dec 22;14(12):16761-16769. doi: 10.1021/acsnano.0c04801. Epub 2020 Dec 7.

Authors

Soumya Sarkar¹, Sinu Mathew^{1

2}, Sandhya Chintalapati³, Ashutosh Rath⁴, Majid Panahandeh-Fard¹, Surajit Saha^{1

5}, Sreetosh Goswami^{1

6}, Sherman Jun Rong Tan⁷, Kian Ping Loh⁷, Mary Scott⁸, Thirumalai Venkatesan^{1

6

9

10}

Affiliations

¹ NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.
² Department of Physics, S.B College, Mahatma Gandhi University, Kerala 686101, India.
³ Tata Institute for Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad, 500107, India.
⁴ CSIR-Institute of Minerals and Materials Technology, Bhubaneshwar, Odisha 751013, India.
⁵ Department of Physics, Indian Institute of Science Education and Research, Bhopal 462066, India.
⁶ Department of Physics, National University of Singapore, Singapore 117542, Singapore.
⁷ Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.
⁸ Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720, United States.
⁹ Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore.
¹⁰ Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore.

PMID: 33284605
DOI: 10.1021/acsnano.0c04801

Abstract

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.

Keywords: 2D materials; interlayer twist; photoluminescence; transition metal dichalcogenides; transition metal oxides.