Czochralski Crystal Growth

Galaxy Compound Semiconductors, Inc. uses the Czochralski crystal growth method for single crystal GaSb and InSb boule production.

Overview of the Czochralski Method:

This method yields large crystals with low defect concentrations and is especially well suited for volatile component single crystal growth such as the antimonides. For GaSb and InSb boule production, Galaxy fabricates their own seeds and employs conventional seed rotation and translation capabilities in the manufacturing process. Specific system temperature gradients and pull rates are a function of the end product compound and boule size.

Czochralski Boule size from Galaxy:

Galaxy routinely grows GaSb crystals ranging from 2" (50mm) to 100mm (4") in diameter and InSb crystal boules ranging from 2" (50mm) to 125mm (5") in diameter. Larger format 150mm (6") InSb boule growth has been successfully demonstrated and is available upon special request

Galaxy's Czochralski process:

Galaxy starts with the highest purity metals (Ga, In, and Sb) which are placed in the growth crucible of the Czochralski puller system. A surrounding inert atmosphere is typically implemented. The quartz crucible is heated until the melting and compound synthesis of the raw elements occurs. Fume off of the more volatile Sb element from the melt requires a steady addition of Sb to the melt as the boule is pulled. Minute amounts of Te are added to the melt for n-type or p-type extrinsic crystal doping, if desired. In the Czochralski method, the seed crystal of either GaSb or InSb is rotated and slowly withdrawn from the melt, forming the initial boule growth. Crystal necking is implemented to reduce boule dislocations. By precisely controlling the temperature gradients, rate of pulling and speed of rotation, it is possible to extract a large, single-crystal, cylindrical boule from the melt onto the rotating seed and rod. The final boule diameter and length is a function of the starting crucible size, melt weight, and total time of the pulling process. The boule must be slowly cooled in order to prevent slip or crystal cracking. The critical parameters of the Czochralski growth process are monitored continuously by CCD cameras, weight measurement, thermocouple temperature readouts, and system pressure gauges.