Lattice dynamics and carrier recombination in GaAs/GaAsBi nanowires

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Abstract
GaAsBi nanowires represent a novel and promising material platform for future nano-photonics. However, the growth of high-quality GaAsBi nanowires and GaAsBi alloy is still a challenge due to a large miscibility gap between GaAs and GaBi. In this work we investigate effects of Bi incorporation on lattice dynamics and carrier recombination processes in GaAs/GaAsBi core/shell nanowires grown by molecular-beam epitaxy. By employing photoluminescence (PL), PL excitation, and Raman scattering spectroscopies complemented by scanning electron microscopy, we show that increasing Bi-beam equivalent pressure (BEP) during the growth does not necessarily result in a higher alloy composition but largely affects the carrier localization in GaAsBi. Specifically, it is found that under high BEP, bismuth tends either to be expelled from a nanowire shell towards its surface or to form larger clusters within the GaAsBi shell. Due to these two processes the bandgap of the Bi-containing shell remains practically independent of the Bi BEP, while the emission spectra of the NWs experience a significant red shift under increased Bi supply as a result of the localization effect.
Funding Information
  • Swedish Foundation for Strategic Research (UKR22-0040, UKR22-0029)
  • KAKENHI from Japan Society for the Promotion of Science (16H05970)
  • Swedish Foundation for International Cooperation in Research and Higher Education (JA2014-5698)
  • Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (SFO-Mat-LiU No 2009 00971)
  • Swedish Research Council (2019-04312)
  • Linköping University

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