GB1415549A - Crystal growing - Google Patents

Abstract

1415549 Single crystals PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES LTD 12 March 1973 [15 March 1972] 11764/73 Heading B1S In a process of growing a single crystal e.g. a rod, by passing a mass of the liquid to be crystallised contained in a hollow cylindrical enclosure through a similar shaped zone heated by radiation and containing therein a steep temperature gradient, heat is dissipated by connecting to the enclosure a body of revolution coaxial with it and wherein the coaxial thickness of this body on the circumference is larger than in the region around the interior longitudinal axis and wherein the material of the body of revolution has thermal properties identical with or approach those of the liquid to be crystallised. A seed crystal may be present. The body of revolution may be a liquid mass in a container which constitutes a double bottom in the cylindrical body, or a solid provided at one end of the cylindrical body, or a disc which can be pressed on the cylinder body. The crystal may be gallium phosphide. As shown in Fig. I, a cylindrical enclosure I which terminates in a conical part 2, contains liquid 4. Radial thermal energy is denoted by arrows 3 and a liquid or solid body is connected to 1, and has a less height at the centre than on the circumference. The crystallisation begins at the tip of the cone. In the process, body 5, causes isotherms e, f, g, which are convex towards the solid in contrast to the isotherms shown in broken lines which would occur in the absence of body 5. Figure 6 shows a modification wherein the bottom 54 of cylindrical enclosure 51, has a concave conical shaft which contains a liquid 52 from which crystallisation is effected. A seed 53 of same diameter as the inner diameter of 51 and which adjoins the bottom 54 is provided in the liquid and provides the body of revolution. Thermal dissipation is provided by rod 56 in contact with bottom 54. Crystallisation occurs on face 55 of the seed.