A numerical investigation of dopant segregation by modified vertical gradient freezing with moderate magnetic and weak electric fields X. Wang a , N. Ma a, * , D.F. Bliss b , G.W. Iseler b a Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, Raleigh, NC 27695, USA b US Air Force Research Laboratory, Sensors Directorate, AFRL/SNHC, 80 Scott Road, Hanscom AFB, MA 01731, USA Received 4 December 2004; received in revised form 17 February 2005; accepted 5 March 2005 Abstract The paper numerically investigates melt growth of doped gallium-antimonide (GaSb) semiconductor crystals by the vertical gradient freeze (VGF) method utilizing a submerged heater. Electromagnetic (EM) stirring can be induced in the gallium-antimonide melt just above the crystal growth interface by applying a small radial electric current in the melt together with an axial magnetic field. The transport of any dopant by the stirring can promote better compositional homogeneity. This investigation presents a numerical model for the unsteady transport of a dopant during the VGF process by submerged heater growth with a moderate axial magnetic field and a weak electric field. Numerical predictions of the dopant distributions in the crystal and in the melt at several different stages during growth are presented. Ó 2005 Elsevier Ltd. All rights reserved. 0020-7225/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijengsci.2005.03.001 * Corresponding author. Tel.: +1 919 515 5231; fax: +1 919 515 7968. E-mail address: nancy_ma@ncsu.edu (N. Ma). www.elsevier.com/locate/ijengsci International Journal of Engineering Science 43 (2005) 908–924