WIAS Preprint No. 1312, (2008)

On unwanted nucleation phenomena at the wall of a VGF chamber



Authors

  • Dreyer, Wolfgang
  • Duderstadt, Frank
  • Eichler, Stefan
  • Naldzhieva, Margarita

2010 Mathematics Subject Classification

  • 74N05

2008 Physics and Astronomy Classification Scheme

  • 61.50.-f 61.82.Fk 62.10.+s 62.20.-x 64.60.Qb 64.70.Ja 68.03.Cd

Keywords

  • crystal growth, homogeneous and heterogenous nucleation, undercooled melt, phase transition, gallium arsenide

Abstract

This is preliminary study on a phenomenon that happens during crystal growth of GaAs in a vertical gradient freeze (VGF) device. Here unwanted polycrystals nucleate at the chamber wall and move into the interior of the crystal. This happens within an undercooled region in the vicinity of the triple point, where the liquid-solid interface meets the chamber wall. The size and shape of that region is modelled by the Gibbs-Thomson law, which will be rederived in this paper. Hereafter we identify the crucial parameter, whose proper adjustment may minimize the undercooled region. Finally we give a simple estimate to calculate and evaluate the energy barrier for homogeneous and heterogeneous nucleation of a solid nucleus in the undercooled melt

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