INFLUENCE OF LOW-GRAVITY LEVEL ON CRYSTAL-GROWTH IN FLOATING-ZONE

The influence of low gravity level on crystal growth in the floating z one, which involves thermocapillary convection, phase change convectio n, thermal and solutal diffusion, is investigated numerically by a fin ite element method for the silicon crystal growth process. The velocit y, temperature, concentration fields and phase change interfaces depen ding on heating temperature and growth rates are analyzed. The influen ce of low gravity level on the concentration is studied especially. Th e results show that the non-uniformities of concentration are about 10 (-3) for growth rate nu(p) = 5.12 x 10(-8) m/s, 10(-2) for nu(p) = 5.1 2 x 10(-7) m/s and relatively larger for larger growth rate in the gra vity level g = 0-9.8 m/s2. The thermocapillary effect is strong in com parison with the Bridgman system, and the level of low gravity is rela tively insensitive for lower growth rates.