GB1491239A - Growing monocrystalline rods from a melt - Google Patents

Abstract

1491239 Growing monocrystalline rods PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 11 Dec 1974 [14 Dec 1973] 53569/74 Heading B1S In a process of growing monocrystalline semiconductor rods by passing a melt thereof horizontally through successive temp, zones, the longitudinal temp, gradient in the cooling zone following the crystallization zone is progressively reduced during the passage of the rod therethrough. As shown in Fig. 5 a monocrystalline rod of GaAs is prepared by passing a SiO 2 boat containing molten GaAs through a tubular chamber 13 surrounded by a furnace composed of heating segments 15- 20 which provide the temp. profile shown in the graph. The solidification front 21 of the melt 23 is convex (9) [Fig. 2 (not shown)] in the direction of arrow 14 and subtends an angle α with the vertical of 5-15‹ [Fig. 3 (not shown)]. As the solidified rod 22 passes through the cooling zone controlled by segments 18 of the furnace the temp. gradient, which is uniform throughout the segment, is reduced linearly from 10 C deg/cm (represented by the section EF of the graph) to 5 C deg/cm (represented by section EF' thereof). The rate of relative movement between the boat and furnace is 1 cm/hr.