TY - JOUR

T1 - Steplike spectral distribution of photoelectrons at the percolation threshold in heavily p -doped GaAs

AU - Poltavtsev, S. V.

AU - Dzhioev, R. I.

AU - Korenev, V. L.

AU - Akimov, I. A.

AU - Kudlacik, D.

AU - Yakovlev, D. R.

AU - Bayer, M.

N1 - Funding Information: The authors thank N. E. Kopteva for useful discussions and assistance in spectroscopic experiments, A. S. Terekhov for providing the samples. I.A.A., D.R.Y., and M.B. acknowledge the Deutsche Forschungsgemeinschaft for financial support through the International Collaborative Research Centre TRR160 (Project No. A3). S.V.P. thanks the Russian Foundation for Basic Research for partial financial support (Research Grant No. 19-52-12046 NNIO_a) and acknowledges St. Petersburg State University (Grant No. 51125686). Publisher Copyright: © 2020 American Physical Society. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/7/13

Y1 - 2020/7/13

N2 - The origin of the steplike shoulder on the high-energy side of the low-temperature photoluminescence spectrum of heavily p-doped GaAs is studied experimentally. It is shown that it is controlled by both the Fermi-Dirac distribution of the holes and the energy distribution of the photoexcited electrons exhibiting a sharp steplike dependence. The latter results from abrupt changes in the energy relaxation rate at the percolation threshold separating localized from delocalized electron states. A comprehensive set of optical techniques based on spin orientation of electrons, namely, the Hanle effect, time- and polarization-resolved photoluminescence, as well as transient pump-probe Faraday rotation, are used for these studies. Two different electron ensembles with substantially different lifetimes of 20 and 280 ps are identified. Their spin relaxation times are longer than 2 ns, so that the spin lifetime is limited by the electron lifetime. The relative contribution of short- and long-lived photoexcited electrons to the emission spectrum changes abruptly at the step in the high-energy photoluminescence tail. For energies above the percolation threshold, the electron states are empty due to fast energy relaxation, while for lower energies the relaxation is suppressed and the majority of photoelectrons populates the states located there.

AB - The origin of the steplike shoulder on the high-energy side of the low-temperature photoluminescence spectrum of heavily p-doped GaAs is studied experimentally. It is shown that it is controlled by both the Fermi-Dirac distribution of the holes and the energy distribution of the photoexcited electrons exhibiting a sharp steplike dependence. The latter results from abrupt changes in the energy relaxation rate at the percolation threshold separating localized from delocalized electron states. A comprehensive set of optical techniques based on spin orientation of electrons, namely, the Hanle effect, time- and polarization-resolved photoluminescence, as well as transient pump-probe Faraday rotation, are used for these studies. Two different electron ensembles with substantially different lifetimes of 20 and 280 ps are identified. Their spin relaxation times are longer than 2 ns, so that the spin lifetime is limited by the electron lifetime. The relative contribution of short- and long-lived photoexcited electrons to the emission spectrum changes abruptly at the step in the high-energy photoluminescence tail. For energies above the percolation threshold, the electron states are empty due to fast energy relaxation, while for lower energies the relaxation is suppressed and the majority of photoelectrons populates the states located there.

KW - OPTICAL-DETECTION

KW - PHOTOLUMINESCENCE

KW - TEMPERATURE

KW - RELAXATION

UR - http://www.scopus.com/inward/record.url?scp=85088710975&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.102.014204

DO - 10.1103/PhysRevB.102.014204

M3 - Article

AN - SCOPUS:85088710975

VL - 102

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 1

M1 - 014204

ER -