Browse Prior Art Database

Growing Single Crystals of High Melting Decomposable Compounds

IP.com Disclosure Number: IPCOM000093070D
Original Publication Date: 1967-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 80K

Publishing Venue

IBM

Related People

Blum, SE: AUTHOR [+2]

Abstract

The apparatus grows large single crystals of compounds whose melting temperatures and dissociating pressures are high. Because of such high temperatures and pressures large single crystals cannot be grown by the conventional Bridgman technique. Such compounds include, but are not limited to, the so-called refractory III-V and II-VI compounds such as GaAs, GaP, AlAs, AlP, ZnS, ZnSe, etc. In general, the compounds are those whose melting points are higher than the softening temperatures, i.e., 1200 degrees C., of quartz. The above-noted compounds are also ones whose dissociating pressure is high so that the maintenance of melt stoichiometry requires pressures that would rupture the softened quartz envelope.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Growing Single Crystals of High Melting Decomposable Compounds

The apparatus grows large single crystals of compounds whose melting temperatures and dissociating pressures are high. Because of such high temperatures and pressures large single crystals cannot be grown by the conventional Bridgman technique. Such compounds include, but are not limited to, the so-called refractory III-V and II-VI compounds such as GaAs, GaP, AlAs, AlP, ZnS, ZnSe, etc. In general, the compounds are those whose melting points are higher than the softening temperatures, i.e., 1200 degrees C., of quartz. The above-noted compounds are also ones whose dissociating pressure is high so that the maintenance of melt stoichiometry requires pressures that would rupture the softened quartz envelope. The drawings are explained with particular reference to the use of apparatus for the preparation of stoichiometric gallium phosphide 50:50. This is for the purpose of illustrating one of many uses of the apparatus.

Crucible 2 containing polycrystalline GaP 1, excess phosphorus 3, and porous quartz wool radiation shields 4 are sealed within quartz ampoule 5 under vacuum conditions. Ampoule 5 is placed in graphite bomb cylinder 6 and held there by removable graphite screw cap 7. The clearance between the quartz tube and graphite is snug and nominal.

Ampoule 5 is so constructed that the lower portion 5A withstands the desired pressure at temperatures to about 1000 degrees C. For GaP, a pressure of about 35 atmospheres is used and tube 5A is 25 mm O.D. x 5 mm I.D. Upper portion 5B of ampoule 5 is of nominal thickness. For GaP, 25 mm O.D. x 19 mm
I.D. tubing is used. At the temperature required for melting, about 1500 degrees C for GaP, tubing 5B softens and it is pushed outwards by the internal phosphorus pressure of 35 atm. Rupture of this port...