Low-temperature photoluminescence of oxide-covered single-layer MoS2

We present a photoluminescence study of single‐layer MoS2 flakes on SiO2 surfaces. We demonstrate that the luminescence peak position of flakes prepared from natural MoS2, which varies by up to 25 meV between individual flakes, can be homogenized by annealing in vacuum. We use HfO2 and Al2O3 layers...

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Published in:Physica status solidi. PSS-RRL. Rapid research letters 2012-03, Vol.6 (3), p.126-128
Main Authors: Plechinger, G., Schrettenbrunner, F.-X., Eroms, J., Weiss, D., Schüller, C., Korn, T.
Format: Article
Language:English
Subjects:
MoS2
photoluminescence
two-dimensional crystals
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Summary:We present a photoluminescence study of single‐layer MoS2 flakes on SiO2 surfaces. We demonstrate that the luminescence peak position of flakes prepared from natural MoS2, which varies by up to 25 meV between individual flakes, can be homogenized by annealing in vacuum. We use HfO2 and Al2O3 layers prepared by atomic layer deposition to cover some of our flakes. In these flakes, we observe a suppression of the low‐energy luminescence peak which appears in asprepared flakes at low temperatures. We infer that this peak originates from excitons bound to surface adsorbates. We also observe different temperature‐induced shifts of the luminescence peaks for the oxide‐covered flakes. This effect stems from the different thermal expansion coefficients of the oxide layers and the MoS2 flakes. It indicates that the single‐layer MoS2 flakes strongly adhere to the oxide layers and are therefore strained. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) In this Letter, Plechinger et al. study the low‐temperature photoluminescence (PL) of single‐layer MoS2 flakes. For flakes that are covered with dielectric oxide layers, the authors observe a suppression of the low‐energy PL peak visible in as‐prepared samples. From the temperature‐induced shift of the PL peaks, they infer that the oxide‐covered flakes are strained.
ISSN:1862-6254
1862-6270
DOI:10.1002/pssr.201105589