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Long spin-flip time and large Zeeman splitting of holes in type-II ZnTe/ZnSe submonolayer quantum dots

Authors
  • Ji, H.1, 2
  • Dhomkar, S.1, 2
  • Wu, R.1, 2
  • Ludwig, J.3, 4
  • Lu, Z.3, 4
  • Smirnov, D.3
  • Tamargo, M. C.2, 5
  • Bryant, G. W.6
  • Kuskovsky, I. L.1, 2
  • 1 Department of Physics, Queens College of CUNY, Queens, New York 11367, USA
  • 2 The Graduate Center of CUNY, New York, New York 10016, USA
  • 3 National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
  • 4 Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
  • 5 Department of Chemistry, City College of CUNY, New York, New York 10031, USA
  • 6 Quantum Measurement Division and Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8423, USA
Type
Published Article
Journal
Journal of Applied Physics
Publisher
American Institute of Physics
Publication Date
Jan 01, 2018
Volume
124
Identifiers
DOI: 10.1063/1.5041478
PMID: 31274882
PMCID: PMC6604638
Source
PubMed Central
License
Unknown

Abstract

The Zeeman splitting and degree of circular polarization (DCP) of photoluminescence (PL) from type-II submonolayer ZnTe/ZnSe quantum dots (QDs) have been investigated in magnetic fields up to 18 T. To explain the observed relative intensities and energy positions of the σ+ and the σ− PL, a non-Boltzmann distribution for holes with ultra-long spin-flip time, confined to submonolayer QDs, is proposed. The g -factor of electrons, located in the ZnSe barriers, was obtained from fitting the temperature dependence of the DCP, and its value is in excellent agreement with that of bulk ZnSe. The g -factor of type-II excitons was extracted by analyzing the Zeeman splitting, from which the g -factor of holes confined within submonolayer ZnTe QDs was found to be ~2.65 ± 0.40. This value is considerably larger than that in bulk ZnTe. Tight-binding calculations using an sp 3 s * model were employed to understand the origin of such an increase. The results of the simulation match the experiment and show that the enhancement of the hole g -factor is mostly caused by a reduced orbital contribution to Zeeman splitting arising from the submonolayer thickness of these QDs.

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