The vertical directional solidification technique for bulk single crystal ingot growth without the seed and without contact to the ampoule wall has been designed and fabricated in our laboratory. VDS technique aim is to promote the spontaneous self seeded and the detached growth in our laboratory (Department of Physics Mithibai College Mumbai India).
Ga(1-X)InX Sb, x = 0.3, 0.5, 0.7 wt %, three ingots of each composition have been grown to know the band gap variation but there was the cracks in ampoule after the 70% ingot growth into ampoule. To avoid the deterotion of the ingots, we have been using the double ampoules for the ingot growths. Typical double ampoule growth arrangement is shown in Fig-1, and single ampoule in Fig-2, this ampoule is taken out from the double ampoule in Fig-1. Ampoule cracks are visible but there were no cracks on the ingots surfaces.
I would first check the thermal expansion coefficient of this material. Some materials - like Bi or water - show an increase of volume with decreasing temperature. I wouldn't expect this but I've seen comparable images after solidification of Bi. The solution is to use a horizontal arrangement and half filled ampoules so that an expansion does not disturb. Another option would be an anisotropy in expansion coefficient. If you have big grains and some of them are specifically aligned there expansion would crack the ampoule as well.
Dear Dattatray Gadkari ,
I think the above explanation from Gert Nolze full of sense as we had exactely the same phenomena's when we grew Fe(Se,Te) crystals in quartz ampoule with vertical bridgman method.
At the end I did not even close the first containing ampoule as I knew that it will brake at low temperature and already solidified crystal will be protected from air by the second ampoule.
Regards
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