Applied Physics A

, Volume 116, Issue 1, pp 85–90

Electron propagation from a photo-excited surface: implications for time-resolved photoemission

  • S.-L. Yang
  • J. A. Sobota
  • P. S. Kirchmann
  • Z.-X. Shen
Article

DOI: 10.1007/s00339-013-8154-9

Cite this article as:
Yang, SL., Sobota, J.A., Kirchmann, P.S. et al. Appl. Phys. A (2014) 116: 85. doi:10.1007/s00339-013-8154-9

Abstract

We perform time- and angle-resolved photoelectron spectroscopy on p-type GaAs(110). We observe an optically excited population in the conduction band, from which the time scales of intraband relaxation and surface photovoltage decay are both extracted. Moreover, the photovoltage shift of the valence band intriguingly persists for hundreds of picoseconds at negative delays. By comparing to a recent theoretical study, we reveal that the negative-delay dynamics reflects the interaction of the photoelectrons with a photovoltage-induced electric field outside the sample surface. We develop a conceptual framework to disentangle the intrinsic electron dynamics from this long-range field effect, which sets the foundation for understanding time-resolved photoemission experiments on a broad range of materials in which poor electronic screening leads to surface photovoltage. Finally, we demonstrate how the long-lasting negative-delay dynamics in GaAs can be utilized to conveniently establish the temporal overlap of pump and probe pulses in a time-resolved photoemission setup.

Copyright information

© Springer-Verlag Berlin Heidelberg (outside the USA) 2013

Authors and Affiliations

  • S.-L. Yang
    • 1
    • 2
  • J. A. Sobota
    • 1
    • 2
  • P. S. Kirchmann
    • 1
  • Z.-X. Shen
    • 1
    • 2
  1. 1.Stanford Institute for Materials and Energy SciencesSLAC National Accelerator LaboratoryMenlo ParkUSA
  2. 2.Geballe Laboratory for Advanced Materials, Departments of Physics and Applied PhysicsStanford UniversityStanfordUSA

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