Transport processes during bulk crystal growth of compound semi conductors

The growth of compound semiconductors is accompanied by temperature and solutal gradients. In the presence of gravity such gradients cause buoyancy convection. These convective flows lead to segregation of species in the solidifying phase and are thus detrimental to the crystal. In addition many of these growth processes involve the introduction of a third phase such as an encapsulant in order to contain a volatile species. For example in vertical Bridgman growth of gallium arsenide the solidifying phase is below the melt while an inert encapsulant such as boron oxide overlies the melt. The interphase between the boron oxide and liquid gallium arsenide is the origin of interfacial tension gradient driven convection which ensues even in the absence of gravity. An extended abstract in lieu of a paper is presented below.