Research output: Contribution to journal › Article › peer-review
Optical spectroscopy of excited exciton states in MoS2 monolayers in van der Waals heterostructures. / Robert, C.; Semina, M. A.; Cadiz, F.; Manca, M.; Courtade, E.; Taniguchi, T.; Watanabe, K.; Cai, H.; Tongay, S.; Lassagne, B.; Renucci, P.; Amand, T.; Marie, X.; Glazov, M. M.; Urbaszek, B.
In: PHYSICAL REVIEW MATERIALS, Vol. 2, No. 1, 011001, 26.01.2018.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Optical spectroscopy of excited exciton states in MoS2 monolayers in van der Waals heterostructures
AU - Robert, C.
AU - Semina, M. A.
AU - Cadiz, F.
AU - Manca, M.
AU - Courtade, E.
AU - Taniguchi, T.
AU - Watanabe, K.
AU - Cai, H.
AU - Tongay, S.
AU - Lassagne, B.
AU - Renucci, P.
AU - Amand, T.
AU - Marie, X.
AU - Glazov, M. M.
AU - Urbaszek, B.
PY - 2018/1/26
Y1 - 2018/1/26
N2 - The optical properties of MoS2 monolayers are dominated by excitons, but for spectrally broad optical transitions in monolayers exfoliated directly onto SiO2 substrates detailed information on excited exciton states is inaccessible. Encapsulation in hexagonal boron nitride (hBN) allows approaching the homogenous exciton linewidth, but interferences in the van der Waals heterostructures make direct comparison between transitions in optical spectra with different oscillator strength more challenging. Here we reveal in reflectivity and in photoluminescence excitation spectroscopy the presence of excited states of the A exciton in MoS2 monolayers encapsulated in hBN layers of calibrated thickness, allowing us to extrapolate an exciton binding energy of approximate to 220 meV. We theoretically reproduce the energy separations and oscillator strengths measured in reflectivity by combining the exciton resonances calculated for a screened two-dimensional Coulomb potential with transfer matrix calculations of the reflectivity for the van der Waals structure. Our analysis shows a very different evolution of the exciton oscillator strength with principal quantum number for the screened Coulomb potential as compared to the ideal two-dimensional hydrogen model.
AB - The optical properties of MoS2 monolayers are dominated by excitons, but for spectrally broad optical transitions in monolayers exfoliated directly onto SiO2 substrates detailed information on excited exciton states is inaccessible. Encapsulation in hexagonal boron nitride (hBN) allows approaching the homogenous exciton linewidth, but interferences in the van der Waals heterostructures make direct comparison between transitions in optical spectra with different oscillator strength more challenging. Here we reveal in reflectivity and in photoluminescence excitation spectroscopy the presence of excited states of the A exciton in MoS2 monolayers encapsulated in hBN layers of calibrated thickness, allowing us to extrapolate an exciton binding energy of approximate to 220 meV. We theoretically reproduce the energy separations and oscillator strengths measured in reflectivity by combining the exciton resonances calculated for a screened two-dimensional Coulomb potential with transfer matrix calculations of the reflectivity for the van der Waals structure. Our analysis shows a very different evolution of the exciton oscillator strength with principal quantum number for the screened Coulomb potential as compared to the ideal two-dimensional hydrogen model.
KW - TRANSITION-METAL DICHALCOGENIDES
KW - VALLEY POLARIZATION
KW - WSE2 MONOLAYER
KW - COHERENCE
KW - WS2
KW - PHOTOLUMINESCENCE
KW - OPTOELECTRONICS
KW - SEMICONDUCTOR
KW - POLARITONS
KW - GENERATION
UR - http://arxiv.org/abs/1712.01548 http://dx.doi.org/10.1103/PhysRevMaterials.2.011001
UR - http://www.mendeley.com/research/optical-spectroscopy-excited-exciton-states-mos2-monolayers-van-der-waals-heterostructures
U2 - 10.1103/PhysRevMaterials.2.011001
DO - 10.1103/PhysRevMaterials.2.011001
M3 - статья
VL - 2
JO - Physical Review Materials
JF - Physical Review Materials
SN - 2475-9953
IS - 1
M1 - 011001
ER -
ID: 36289917