Population dynamics and dephasing of excitons and electron-hole pairs in polytype wurtzite/zinc-blende InP nanowires

H. P. Wagner, M. Kaveh, Q. Gao, H. Tan, C. Jagadish, and W. Langbein
Phys. Rev. B 95, 045305 – Published 18 January 2017

Abstract

We investigated the dephasing and population dynamics of electron-hole (e-h) pairs and excitons in vapor-liquid-solid grown polytype wurtzite/zinc-blende (WZ/ZB) InP nanowires (NWs) using heterodyne four-wave mixing (HFWM) in three-beam configuration at temperatures from 80 to 270 K. The photon energy of the 100 fs excitation pulses was varied to predominantly excite either mobile excitons and e-h pairs or indirect WZ/ZB excitons. The population dynamics reveal a multiexponential decay with time constants ranging over six orders of magnitude. The dynamics has been interpreted by a coupled rate equation model which considers WZ and ZB electron states, donor electron states, and band bending trapping holes to the surface. The model reproduces the essential features of the experimentally observed dynamics at different excitation energies, fluences, and lattice temperatures. Intraband thermalization is reached within 5–50 ps, after which the nonradiative recombination dominates the dynamics. Notably, the screenable surface band bending results in long-lived spatially separated carriers, causing a photogenerated, spatially separated electron and hole density which is dominating the long-lived dynamics.

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  • Received 29 June 2016
  • Revised 21 November 2016

DOI:https://doi.org/10.1103/PhysRevB.95.045305

©2017 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
Condensed Matter, Materials & Applied Physics

Authors & Affiliations

H. P. Wagner1,*, M. Kaveh2, Q. Gao3, H. Tan3, C. Jagadish3, and W. Langbein4

  • 1Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA
  • 2Department of Physics and Astronomy, James Madison University, Harrisonburg, Virginia 22807, USA
  • 3Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra ACT 2601, Australia
  • 4School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, United Kingdom

  • *wagnerhp@ucmail.uc.edu

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Issue

Vol. 95, Iss. 4 — 15 January 2017

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