Single-crystal – oriented-crystal – and epitaxy growth processes; – Processes of growth from liquid or supercritical state – Having pulling during growth
Reexamination Certificate
2007-08-14
2007-08-14
Kunemund, Robert (Department: 1722)
Single-crystal, oriented-crystal, and epitaxy growth processes;
Processes of growth from liquid or supercritical state
Having pulling during growth
C117S014000, C117S020000, C117S940000
Reexamination Certificate
active
10781094
ABSTRACT:
A method is described for making low-stress single crystals with a hexagonal crystal structure, which has a crystallographic c-axis perpendicular to a [0001] surface. A single crystal maintained at a temperature under the melting point of the crystal raw material is dipped in a melt of the crystal raw material, whereby a solid-liquid phase boundary is formed. The crystal is subsequently drawn with an upwardly directed drawing motion e.g. by the Czochralski method. The method is characterized by drawing the crystal along the c-axis so that a temperature gradient of at least 30 K/cm is present in the crystal within a centimeter of the solid-liquid phase boundary and by subsequently performing a tempering treatment on the resulting single crystal. The method is especially suitable for corundum crystals, such as sapphire, which are used as substrates for semiconductor components, such as LEDs.
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K.I Schaffers et al: “Progress in the Growth of YB . . . ” Journal of Crystal Growth 225, 2001, pp. 449-453.
Schweizer Markus
Speit Burkhard
Sprenger Dirk
Kunemund Robert
Schott AG
Striker Michael J.
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