Vertical Gradient Freezing using Submerged Heater Growth with Rotation and with Weak Magnetic and Electric Fields

Investigations for the melt growth gallium-antimonide (GaSb) semiconductor crystals are underway at the US Air Force Research Laboratory at Hanscom Air Force Base by the vertical gradient freeze (VGF) method utilizing a submerged heater. Electromagnetic stirring can be induced in the gallium-antimonide melt just above the crystal growth interface by applying a weak radial electric current in the melt together with a weak axial magnetic field. A force convection in the melt can be induced by rotating the heater. This paper uses a Chebyshev spectral collocation method and investigates the effects of heater rotation and electromagnetic stirring on the melt motion during the VGF process using a submerged heater. Clockwise and counterclockwise rotations of the heater augment and opposes the flow induced by the electromagnetic stirring, respectively. The radial velocity along the crystal–melt interface is proportional to both the strength of the electromagnetic stirring and the clockwise rotation of the heater. A relatively low rotation rate in the clockwise direction significantly increases this radial velocity. 2005 Elsevier Inc. All rights reserved.