CONVECTIVE MASS TRANSPORT DURING BULK GROWTH OF SEMICONDUCTOR CRYSTALS WITH STEADY MAGNETIC FIELDS

During a bulk-growth process, a single crystal is grown by the slow solidification from a body of molten semiconductor, or melt. Since most molten semiconductors have large electrical conductivities, a magnetic field can be used to suppress deleterious hydrodynamic instabilities and to tailor the laminar melt motion during crystal growth. A primary goal is to tailor the convective mass transport of dopants and species in the melt in order to produce crystals with uniform compositions. The optimal magnetic field depends on the process and on the type of semiconductor. This paper reviews: (1) the development of oxygen-transport control in the growth of large-diameter silicon crystals by the Czochralski process; (2) the use of magnetic fields to improve the quality of bulk-grown crystals of compound semiconductors, such as gallium-arsenide and indium-phosphide; (3) the benefits of magnetic fields for the floating zone growth of high-purity, dislocation-free silicon crystals; (4) the thermoelectromagnetic convection arising from the application of a magnetic field; and (5) the benefits of very strong magnetic fields for solid-solution crystals grown by the vertical Bridgman process.