Simulation of radial dopant segregation in vertical Bridgman growth of GaSe, a semiconductor with anisotropic solid-phase thermal conductivity

Hanjie Lee, Arne J. Pearlstein

Research output: Contribution to journalArticlepeer-review

Abstract

For a range of growth conditions of practical interest, we simulate liquid- and solid-phase dopant distributions and radial segregation for several dopants (In, Sn, Cu, Se, Zn, and Cd) in vertical Bridgman growth of the nonlinear optical material gallium monoselenide. Besides these dopants, which have been used to modify the properties of Bridgman-grown GaSe and have segregation coefficients in the range 0.01≤k̃≤0.3, we also consider a hypothetical dopant with k̃ = 0.8. The computational model accounts for the anisotropic solid-phase thermal conductivity characteristic of nonlinear optical materials, interface deformation, convection in the melt, and conduction in the ampoule wall. The results show a strong dependence of radial segregation on growth rate over the range 0.25 μm s-1 ≤U≤3 μm s-1, and a much weaker dependence on the maximum ampoule-wall temperature gradient over the range 15°C cm-1 ≤dTb(0)/dz≤60°C cm-1. Overall radial segregation depends weakly on whether the melting temperature is "centered" between the high and low temperatures, and is insensitive to both the 23°C difference in the measured values of the melting temperature, and the large difference between the two measurements of the enthalpy of fusion. The overall radial segregation depends approximately linearly on the product of 1 - k̃ and the growth rate U over the entire range of segregation coefficients and growth rates considered. Radial segregation computed using an isotropic conductivity (one-third the trace of the conductivity tensor) gives results qualitatively different than predictions using the anisotropic conductivity. We also show how localized ampoule-wall heating in the "adiabatic" zone of a three-zone Bridgman furnace can dramatically alter radial segregation by creating one or more additional, weak, toroidal vortices just above the interface.

Original languageEnglish (US)
Pages (from-to)148-170
Number of pages23
JournalJournal of Crystal Growth
Volume231
Issue number1-2
DOIs
StatePublished - Sep 2001

Keywords

  • A1. Computer simulation
  • A1. Convection
  • A1. Doping
  • A1. Segregation
  • A2. Bridgman technique
  • B2. Nonlinear optical materials

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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