Cho Chullhee, Wong Joeson, Taqieddin Amir, Biswas Souvik, Aluru Narayana R, Nam SungWoo, Atwater Harry A
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
Department of Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125, United States.
Nano Lett. 2021 May 12;21(9):3956-3964. doi: 10.1021/acs.nanolett.1c00724. Epub 2021 Apr 29.
Interlayer excitons in heterobilayers of transition-metal dichalcogenides (TMDCs) have generated enormous interest due to their permanent vertical dipole moments and long lifetimes. However, the effects of mechanical strain on the optoelectronic properties of interlayer excitons in heterobilayers remain relatively uncharacterized. Here, we experimentally demonstrate strain tuning of Γ- interlayer excitons in molybdenum disulfide and tungsten diselenide (MoS/WSe) wrinkled heterobilayers and obtain a deformation potential constant of ∼107 meV/% uniaxial strain, which is approximately twice that of the intralayer excitons in the constituent monolayers. We further observe a nonmonotonic dependence of the interlayer exciton photoluminescence intensity with strain, which we interpret as being due to the sensitivity of the Γ point to band hybridization arising from the competition between in-plane strain and out-of-plane interlayer coupling. Strain engineering with interlayer excitons in TMDC heterobilayers offers higher strain tunability and new degrees of freedom compared to their monolayer counterparts.
过渡金属二硫属化物(TMDCs)异质双层中的层间激子因其永久垂直偶极矩和长寿命而引起了极大关注。然而,机械应变对异质双层中层间激子光电特性的影响仍相对缺乏研究。在此,我们通过实验证明了在二硫化钼和二硒化钨(MoS₂/WSe₂)褶皱异质双层中Γ层间激子的应变调控,并获得了约107 meV/%单轴应变的形变势常数,这大约是组成单层中内层激子的两倍。我们还进一步观察到层间激子光致发光强度随应变的非单调依赖性,我们将其解释为是由于Γ点对平面内应变和平面外层间耦合之间竞争引起的能带杂化的敏感性。与单层TMDCs相比,TMDCs异质双层中的层间激子应变工程提供了更高的应变可调性和新的自由度。