Ultralocalized Optoelectronic Properties of Nanobubbles in 2D Semiconductors.

The optical properties of transition-metal dichalcogenides have previously been modified at the nanoscale by using mechanical and electrical nanostructuring. However, a clear experimental picture relating the local electronic structure with emission properties in such structures has so far been lacking. Here, we use a combination of scanning tunneling microscopy (STM) and near-field photoluminescence (nano-PL) to probe the electronic and optical properties of single nanobubbles in bilayer heterostructures of WSe2 on MoSe2. We show from tunneling spectroscopy that there are electronic states deeply localized in the gap at the edge of such bubbles, which are independent of the presence of chemical defects in the layers. We also show a significant change in the local band gap on the bubble, with a continuous evolution to the edge of the bubble over a length scale of ∼20 nm. Nano-PL measurements observe a continuous redshift of the interlayer exciton on entering the bubble, in agreement with the band-to-band transitions measured by STM. We use self-consistent Schrödinger-Poisson simulations to capture the essence of the experimental results and find that strong doping in the bubble region is a key ingredient to achieving the observed localized states, together with mechanical strain.

[1]  A. Pan,et al.  Morphology Deformation and Giant Electronic Band Modulation in Long-Wavelength WS2 Moiré Superlattices. , 2022, Nano letters.

[2]  Kenji Watanabe,et al.  Ultrasharp Lateral p-n Junctions in Modulation-Doped Graphene. , 2022, Nano letters.

[3]  Timothy C. Berkelbach,et al.  Dark-Exciton Driven Energy Funneling into Dielectric Inhomogeneities in Two-Dimensional Semiconductors. , 2022, Nano letters.

[4]  H. Choo,et al.  Drift-dominant exciton funneling and trion conversion in 2D semiconductors on the nanogap , 2022, Science advances.

[5]  B. Gerardot,et al.  Quantum photonics with layered 2D materials , 2022, Nature Reviews Physics.

[6]  Bjarke S. Jessen,et al.  Nanometer-Scale Lateral p–n Junctions in Graphene/α-RuCl3 Heterostructures , 2021, Nano letters.

[7]  B. Gerardot,et al.  Optical dipole orientation of interlayer excitons in MoSe2−WSe2 heterostacks , 2021, Physical Review B.

[8]  M. Lipson,et al.  Nano-spectroscopy of excitons in atomically thin transition metal dichalcogenides , 2021, Nature Communications.

[9]  P. El-Khoury,et al.  Imaging Charged Exciton Localization in van der Waals WSe2/MoSe2 Heterobilayers. , 2021, The journal of physical chemistry letters.

[10]  Xiaodong Xu,et al.  Moiré trions in MoSe2/WSe2 heterobilayers , 2021, Nature Nanotechnology.

[11]  Thomas J. Kempa,et al.  Anomalous Room-Temperature Photoluminescence from Nanostrained MoSe2 Monolayers , 2021, ACS Photonics.

[12]  Darien J. Morrow,et al.  Trapping interlayer excitons in van der Waals heterostructures by potential arrays , 2021, Physical Review B.

[13]  J. Rho,et al.  Inducing and Probing Localized Excitons in Atomically Thin Semiconductors via Tip‐Enhanced Cavity‐Spectroscopy , 2021, Advanced Functional Materials.

[14]  K. Banerjee,et al.  Defect and strain engineering of monolayer WSe2 enables site-controlled single-photon emission up to 150 K , 2021, Nature Communications.

[15]  H. Atwater,et al.  Highly Strain-Tunable Interlayer Excitons in MoS2/WSe2 Heterobilayers. , 2021, Nano letters.

[16]  Dong Yun Lee,et al.  Tip‐Induced Nano‐Engineering of Strain, Bandgap, and Exciton Funneling in 2D Semiconductors , 2021, Advanced materials.

[17]  M. Lukin,et al.  Excitons in a reconstructed moiré potential in twisted WSe2/WSe2 homobilayers , 2021, Nature Materials.

[18]  A. Pasupathy,et al.  Deep moiré potentials in twisted transition metal dichalcogenide bilayers , 2020, Nature Physics.

[19]  J. Hone,et al.  Diffusivity Reveals Three Distinct Phases of Interlayer Excitons in MoSe_{2}/WSe_{2} Heterobilayers. , 2020, Physical review letters.

[20]  S. Ferrari,et al.  Author contributions , 2021 .

[21]  Zachary D. Schultz,et al.  From SERS to TERS and Beyond: Molecules as Probes of Nanoscopic Optical Fields. , 2020, The journal of physical chemistry. C, Nanomaterials and interfaces.

[22]  J. Hone,et al.  Exciton dipole orientation of strain-induced quantum emitters in WSe2. , 2020, Nano letters.

[23]  J. Kysar,et al.  Imaging strain-localized exciton states in nanoscale bubbles in monolayer WSe2 at room temperature , 2020, 2003.01789.

[24]  T. Pedersen,et al.  Interlayer excitons in van der Waals heterostructures: Binding energy, Stark shift, and field-induced dissociation , 2020, Scientific Reports.

[25]  Moshe G. Harats,et al.  Dynamics and efficient conversion of excitons to trions in non-uniformly strained monolayer WS2 , 2019, Nature Photonics.

[26]  Xiaodong Xu,et al.  One-Dimensional Moir\'e Excitons in Transition-Metal Dichalcogenide Heterobilayers , 2019, 1912.06628.

[27]  A. Pasupathy,et al.  Tunable strain soliton networks confine electrons in van der Waals materials , 2019, 1910.14231.

[28]  F. Bobba,et al.  The Effects of Atomic Scale Strain Relaxation on the Electronic Properties of Monolayer MoS2. , 2019, ACS nano.

[29]  Xiaodong Xu,et al.  Visualizing electrostatic gating effects in two-dimensional heterostructures , 2019, Nature.

[30]  M. Lorke,et al.  Quantum-Dot-Like States in Molybdenum Disulfide Nanostructures Due to the Interplay of Local Surface Wrinkling, Strain, and Dielectric Confinement. , 2019, Nano letters.

[31]  V. Kravets,et al.  Strained Bubbles in van der Waals Heterostructures as Local Emitters of Photoluminescence with Adjustable Wavelength , 2019, ACS Photonics.

[32]  M. Lukin,et al.  Electrical control of interlayer exciton dynamics in atomically thin heterostructures , 2018, Science.

[33]  F. Guinea,et al.  Strain-induced bound states in transition-metal dichalcogenide bubbles , 2018, 2D Materials.

[34]  P. Schuck,et al.  Optically Discriminating Carrier-Induced Quasiparticle Band Gap and Exciton Energy Renormalization in Monolayer MoS_{2}. , 2017, Physical review letters.

[35]  Jong-Hyun Ahn,et al.  Local Strain Induced Band Gap Modulation and Photoluminescence Enhancement of Multilayer Transition Metal Dichalcogenides , 2017 .

[36]  G. Pizzi,et al.  Strain-induced polar discontinuities in two-dimensional materials from combined first-principles and Schrödinger-Poisson simulations , 2017, 1705.01303.

[37]  Brian D Gerardot,et al.  Deterministic strain-induced arrays of quantum emitters in a two-dimensional semiconductor , 2016, Nature Communications.

[38]  T. Heinz,et al.  Population inversion and giant bandgap renormalization in atomically thin WS2 layers , 2015, Nature Photonics.

[39]  P. Ajayan,et al.  Optoelectronic crystal of artificial atoms in strain-textured molybdenum disulphide , 2015, Nature Communications.

[40]  J. Hone,et al.  Measurement of the optical dielectric function of monolayer transition-metal dichalcogenides: MoS 2 , Mo S e 2 , WS 2 , and WS e 2 , 2014, 1610.04671.

[41]  G. Burkard,et al.  k·p theory for two-dimensional transition metal dichalcogenide semiconductors , 2014, 1410.6666.

[42]  Evan J. Reed,et al.  Intrinsic Piezoelectricity in Two-Dimensional Materials , 2012 .