Homogeneity of Vertical Magnetic Field Applied LEC GaAs Crystal

Abstract

The effect of a vertical magnetic field on both GaAs melt temperature distribution and the homogeneity of LEC GaAs crystals is studied. It is found that although melt flow fluctuations that introduce irregular striations can easily be eliminated, laminar thermal convection cannot be completely suppressed by the magnetic field. This residual laminar thermal convection degrades both microscopic and macroscopic homogeneity of crystals. However, striation-free crystals having a doped Se concentration variation of less than 2.5% across the wafer are obtained by optimizing the seed rotation rate in the presence of such a magnetic field.