Configuration dependence of band-gap narrowing and localization in diluteGaAs1−xBixalloys Academic Article uri icon

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abstract

  • Anion substitution with bismuth (Bi) in III-V semiconductors is an effective method for experimental engineering of the band gap Eg at low Bi concentrations, in particular in gallium arsenide (GaAs). The inverse Bi-concentration dependence of Eg has been found to be linear at low concentrations x and dominated by a valence band-defect level anticrossing between As and Bi occupied p levels. This dependence breaks down at high concentrations where empirical models accounting only for the As-Bi interaction are not applicable. Predictive models for the valence band hybridization require a first-principle understanding which can be obtained by density functional theory with the main challenges being the proper description of Eg and the spin-orbit coupling. By using an efficient method to include these effects, it is shown here that at high concentrations Eg is modified mainly by a Bi-Bi p orbital interaction and by the large Bi atom-induced strain. This points to the role of different atomic configurations obtained by varying the experimental growth conditions in engineering arsenide band gaps, in particular for telecommunication laser technology.

authors

  • Bannow, Lars C
  • Rubel, Oleg
  • Badescu, Stefan C
  • Rosenow, Phil
  • Hader, Jörg
  • Moloney, Jerome V
  • Tonner, Ralf
  • Koch, Stephan W

publication date

  • May 16, 2016