APPLICATION OF AN AXIAL MAGNETIC-FIELD TO VERTICAL GRADIENT FREEZE GSAS SINGLE-CRYSTAL GROWTH

Abstract

We have developed a growth technique for vertical gradient freeze GaAs single crystals, in which an axial magnetic field can be applied up to 1500 G. From calculations, the application of an axial magnetic field of 1000 G was found to be enough for suppressing the Marangoni flow and promote the stability of the thermal environment throughout the whole melt during the crystal growth, enhancing the production yield. Through the growth and characterization of the AM-VGF (axial magnetic field applied-vertical gradient freeze) GaAs single crystal lightly doped with indium of similar to 10(18) cm(-3), the effects of the application of an axial magnetic field to improve crystal quality were confirmed. Low defect, nearly striation-free single crystals can be obtained with this technique. The maximum deviations of the electrical properties for the growth direction and the optical characteristics for the radial direction in the crystal are 15% and 5%, respectively.