Understanding and Curing Structural Defects in Colloidal GaAs Nanocrystals

Vishwas Srivastava, Wenyong Liu, Eric M. Janke, Vladislav Kamysbayev, Alexander S. Filatov, Cheng Jun Sun, Byeongdu Lee, Tijana Rajh, Richard D Schaller, Dmitri V. Talapin

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

GaAs is one of the most important semiconductors. However, colloidal GaAs nanocrystals remain largely unexplored because of the difficulties with their synthesis. Traditional synthetic routes either fail to produce pure GaAs phase or result in materials whose optical properties are very different from the behavior expected for quantum dots of direct-gap semiconductors. In this work, we demonstrate a variety of synthetic routes toward crystalline GaAs NCs. By using a combination of Raman, EXAFS, transient absorption, and EPR spectroscopies, we conclude that unusual optical properties of colloidal GaAs NCs can be related to the presence of Ga vacancies and lattice disorder. These defects do not manifest themselves in TEM images and powder X-ray diffraction patterns but are responsible for the lack of absorption features even in apparently crystalline GaAs nanoparticles. We introduce a novel molten salt based annealing approach to alleviate these structural defects and show the emergence of size-dependent excitonic transitions in colloidal GaAs quantum dots.

Original languageEnglish
Pages (from-to)2094-2101
Number of pages8
JournalNano Letters
Volume17
Issue number3
DOIs
Publication statusPublished - Mar 8 2017

Keywords

  • colloidal nanocrystals
  • EXAFS
  • excitonic transitions
  • Gallium arsenide
  • lattice disorder
  • molten salt
  • Raman spectroscopy
  • transient absorption

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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    Srivastava, V., Liu, W., Janke, E. M., Kamysbayev, V., Filatov, A. S., Sun, C. J., Lee, B., Rajh, T., Schaller, R. D., & Talapin, D. V. (2017). Understanding and Curing Structural Defects in Colloidal GaAs Nanocrystals. Nano Letters, 17(3), 2094-2101. https://doi.org/10.1021/acs.nanolett.7b00481