Growth and characterization of highly mismatched GaN1-xSbx alloys

K.M. Yu, S. V. Novikov, Min Ting, W.L. Sarney, S.P. Svensson, M. Shaw, R.W. Martin, W. Walukiewicz, C.T. Foxon

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Abstract

A systematic investigation on the effects of growth temperature, Ga flux, and Sb flux on the incorporation of Sb, film structure, and optical properties of the GaN1-xSbx highly mismatched alloys (HMAs) was carried out. We found that the direct bandgap ranging from 3.4 eV to below 1.0 eV for the alloys grown at low temperature. At the growth temperature of 80 degrees C, GaN1-xSbx with x>6% losses crystallinity and becomes primarily amorphous with small crystallites of 2-5 nm. Despite the range of microstructures found for GaN1-xSbx alloys with different composition, a well-developed absorption edge shifts from 3.4 eV (GaN) to close to 2 eV for samples with a small amount, less than 10% of Sb. Luminescence from dilute GaN1-xSbx alloys grown at high temperature and the bandgap energy for alloys with higher Sb content are consistent with a localized substitutional Sb level E-Sb at similar to 1.1 eV above the valence band of GaN. The decrease in the bandgap of GaN1-xSbx HMAs is consistent with the formation of a Sb-derived band due to the anticrossing interaction of the Sb states with the valence band of GaN.
Original languageEnglish
Article number123704
Number of pages8
JournalJournal of Applied Physics
Volume116
Issue number12
Early online date24 Sep 2014
DOIs
Publication statusPublished - 28 Sep 2014

Keywords

  • GaN
  • GaSb
  • HMAs
  • film structures
  • growth temperature
  • Ga flux
  • Sb flux

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