6.152J3.155J Czochralski growth of single crystals: impuri still boundary lay B field suppresses convection of ions(reactive)---s deflecting them from interface Bridgman growth of GaAs T6200c d/ox 100C/=> dislocation density 10/cm mm/hr6.152J/3.155J 11 21 Nov.26 , 2003 6.12J / 3.155J Microelectronic processing Impurities must diffuse across still boundary layer. B field suppresses convection of ions (reactive) deflecting them from interface ƒ Boundary layer keeps impurities away from solid-liquid interface Czochralski growth of single crystals: impurities 22 Nov.26 , 2003 6.12J / 3.155J Microelectronic processing Bridgman growth of GaAs dT/dx < 100C/cm => dislocation density < 103/cm2 but melt-ampule contact => lower resistivity. GaAs in quartz ampule: GaAs As T § 6200C Convection barrier Tm § v § mm/hr. r § 10 MWcm 2 - 5 x 103 dislocations /cm2 GaAs in BN ampule: Tm Vertical Bridgman To correct contact problems, use vertical Bridgman