22 - The Role of Marangoni Convection in Crystal Growth

Abstract

In the crystal growth from the melt with free surface, such as the Czochralski or floating-zone growth, the surface tension-driven, Marangoni convection occurs in the melt because the temperature gradient and concentration gradient in the mixed materials should exist along the melt surface. Melt convection affects heat and mass transport in the melt and crystal, and consequently, the spatial homogeneity of impurities or dopants and formation of macro and microdefects in the crystals with regard to the crystal quality. Therefore, it is important to acquire correct knowledge of Marangoni convection together with other convections in the melt. In this chapter, the general considerations of thermo- and solutocapillary flows, Marangoni–Benard instability and hydrothermal wave instability were described, and then Marangoni convection in the typical growth processes was discussed. Moreover, the measured values of surface tension and its temperature coefficients of molten materials, which are key thermophysical properties in numerical simulations and discussions on Marangoni convection, were introduced.