Linewidth Broadening and Tunneling of Excitons Bound to N Pairs in Dilute GaAs:N: Article No. 145704

Brian Fluegel, Kirstin Alberi, Kerstin Volz, Wolfgang Stolz, Daniel Beaton

Research output: Contribution to journalArticlepeer-review

2 Scopus Citations

Abstract

The exciton bound to a pair of nitrogen atoms situated at nearby lattice sites in dilute GaAs:N provides an energetically uniform electronic system, spectrally distinct from pairs with larger or smaller separations, and can even be grown with a uniform pair orientation in the crystal. We use photoluminescence excitation spectroscopy on an ensemble of N pairs to study the narrow continuous energy distribution within two of the individual exchange- and symmetry-split exciton states. Inhomogeneous linewidths of 50-60 ueV vary across the crystal on a mesoscopic scale and can be 30 ueV at microscopic locations indicating that the homogeneous linewidth inferred from previous time-domain measurements is still considerably broadened. While excitation and emission linewidths are similar, results show a small energy shift between them indicative of exciton transfer via phonon-assisted tunneling between spatially separated N pairs. We numerically simulate the tunneling in a spatial network of randomly distributed pairs having a normal distribution of bound exciton energies. Comparing the ensemble excitation-emission energy shift with the measured results shows that the transfer probability is higher than expected from the dilute pair concentration and what is known of the exciton wavefunction spatial extent. Both the broadening and the exciton transfer have implications for the goal of pair-bound excitons as a single- or multi-qubit system.
Original languageAmerican English
Number of pages7
JournalJournal of Applied Physics
Volume125
Issue number14
DOIs
StatePublished - 2019

NREL Publication Number

  • NREL/JA-5K00-73378

Keywords

  • atomic and molecular spectra
  • excitation energies
  • excitons
  • phonons
  • photoluminescence excitation spectroscopy
  • photoluminescence spectroscopy
  • quantum computing
  • semiconductors

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