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US3628998A Expired / Lapsed US ⏱️ 0.0 years remaining

Method for growth of a mixed crystal with controlled composition

Assignee: International Business Machines Corp
•
Filing: 1969-09-23
•
Granted: 1971-12-21
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Expires: 1989-09-23
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Abstract

Abstract A mixed crystal e.g., GaxIn1 xP, of controlled composition in the growth direction, either of substantially homogeneous composition or of variable composition, is prepared from the melt or liquid solution by the method of this disclosure. Illustratively, the starting materials are two different pure III-V compounds with different melting points, e.g., GaP and InP, which are to be the components from which the mixed crystal is to be grown. A three-layered composite or charge is fabricated consisting of a layer of the lower melting compound flanked on both top and bottom by layers of the higher melting compound. The composite is established in a crucible which is sealed in a quartz ampul in vacuum to form an assembly. When an overpressure of either an inert or a reactive gas is required, the quartz ampul is sealed inside a stronger container, e.g., of graphite. The assembly is allowed to equilibrate isothermally in a furnace of a given temperature to yield a liquid solution from which the desired solid solution of mixed crystal can crystallize. For crystal growth with homogeneous composition the assembly is lowered slowly into a slightly cooler temperature zone of the furnace and crystallization of the mixed crystal occurs at the lower one of the two liquid-solid interfaces. A single crystal is obtained by epitaxial growth when the substrate is a singlecrystal seed. As the liquid becomes depleted in the higher melting component at the growth interface, the dissolution of the higher melting component at the upper liquid-solid interface replenishes the composition of the liquid. This physical process is incrementally small, i.e., it occurs slowly, and results in the composition of the liquid remaining essentially in a steady state of constant composition. Illustratively, GaxIn1 xP cylindrical ingots of approximately 1 cm. length X 1.5 cm. diameter are readily produced from the components of GaP and InP by the practice of this disclosure.

Inventors

  • 👤 Samuel E Blum
  • 👤 Richard J Chicotka

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 14:45
CPC Classifications
C; C30; C30B; C30B11/00; C30B11/04; C30B11/06; Y; Y10; Y10S; Y10S117/00; Y10S117/90

Claims Analysis

Total Claims: 16
Claim 1
Independent Claim 91 words
A method for growing a crystalline region of mixed-crystal system of substantially homogeneous composition in the growth direction by the steps of: establishing a first solid-liquid interface at one location adjacent a substantially equilibrium liquid zone for said composition; establishing a second solid-liquid interface at another location adjacent said liquid zone; controlling a temperature differential between said first and second locations for respectively dissolving said first solid into said liquid zone at said first solid-liquid interface, and depositing said crystalline region of said substantially homogeneous composition at said second solid-liquid interface.
Claim 2
Independent Claim 163 words
A method for growing a crystalline region of a mixed-crystal system with substantially homogeneous composition in the growth direction by the steps of: establishing a charge having first, second and third solid layers, said first layer being of one component of said mixed-crystal system, and said second and third layers being of another component of said mixed-crystal system, said first layer being intermediate said second and third layers, and having lower melting point and complete solubility therewith over a range of compositions; establishing a substantially equilibrium condition of said charge at a temperature above the melting point of said intermediate layer and below the melting point of said second and third layers to obtain a liquid zone with a given composition with first and second liquid-solid interfaces in said second and third solid layers; lowering the temperature at one said solid-liquid interface between said intermediate liquid zone and one said adjacent solid layer; and growing said crystalline region at said latter liquid-solid interface.
Claim 3
Dependent Claim 15 words
A method as set forth in claim 3 wherein said crystalline region is grown epitaxially.
Claim 4
Dependent Claim 15 words
A method as set forth in claim 4 wherein said crystalline region is single crystalline.
Claim 5
Dependent Claim 16 words
A method as set forth in claim 3 wherein said mixed-crystal system is a III-V semiconductor.
Claim 6
Dependent Claim 30 words
A method as set forth in claim 4 wherein said mixed-crystal system is GaP-InP, said composition is GaxIn1 xP, said one component being InP and said anotHer component being GaP.
Claim 7
Independent Claim 172 words
A method for growing a single crystal with substantially homogeneous composition in the growth direction of a mixed-crystal system with at least two components and with a range of complete solubility in both the liquid phase and the solid phase by the steps of: establishing a charge consisting of a solid region of one component of said mixed-crystal system with a relatively low melting point adjacent to at least one separated solid region of another component of said mixed-crystal system with a relatively high melting point; heating said charge at a given temperature higher than said relatively low melting point but lower than said relatively high melting point for sufficient time to establish equilibrium of a resultant liquid region with said one solid region so that there is a percentage composition in said liquid region of each of said components of said mixed-crystal system according to the equilibrium solubilities at said given temperature; and lowering the temperature at a location other than said one solid-liquid interface and growing thereat said single crystal.
Claim 8
Independent Claim 101 words
A method for growing a solid region of a mixed-crystal system with controlled composition in the growth direction by the steps of: establishing a substantially equilibrium liquid region for said composition; establishing a first solid region of one component of said mixed-crystal system in contact with said liquid region at one temperature and a second solid region of said one component in contact with said liquid region at another location at another temperature; and controlling the temperatures at said first and second locations for dissolving one solid component and depositing said solid region with said controlled composition at said other location.
Claim 9
Dependent Claim 29 words
A method as set forth in claim 9 wherein said controlled composition of said solid region includes a plurality of discrete layers with different compositions in the growth direction.
Claim 10
Dependent Claim 19 words
A method as set forth in claim 9 wherein said controlled composition is continuously variable in the growth direction.
Claim 11
Independent Claim 172 words
A method for growing a solid zone with controlled composition in the growth direction of a mixed-crystal system with at least two components and with a range of complete solubility in both the liquid phase and the solid phase by the steps of: establishing a charge consisting of a solid region of one component of said mixed-crystal system with a relatively low melting point adjacent to at least one separated solid region of another component of said mixed-crystal system with a relatively high melting point; heating said charge at a given temperature higher than said relatively low melting point but lower than said relatively high melting point for sufficient time to establish equilibrium of a resultant liquid phase region with said one solid region so that there is a percentage composition in said liquid region of each of said components of said mixed-crystal system according to the equilibrium solubilities at said given temperature; and lowering the temperature at a location other than said one solid-liquid interface and growing thereat said solid zone.
Claim 12
Dependent Claim 14 words
A method as set forth in claim 12 wherein said solid zone is crystalline.
Claim 13
Dependent Claim 15 words
A method as set forth in claim 13 wherein said solid zone is single crystalline.
Claim 14
Dependent Claim 19 words
A method as set forth in claim 12 wherein said solid zone has homogeneous composition in the growth direction.
Claim 15
Dependent Claim 25 words
A method as set forth in claim 12 wherein said solid zone includes a plurality of discrete layers with different compositions in the growth direction.
Claim 16
Dependent Claim 23 words
A method as set forth in claim 12 wherein said controlled composition of said solid zone is continuously variable in the growth direction.

References Cited (Backward Citations)

US3447976A Cited
US3428438A Cited
US3514265A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1974-12-20 1975-06-21 1975-12-21 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1978-12-20 1979-06-21 1979-12-21 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1982-12-20 1983-06-21 1983-12-21 $7700.00 Window Closed / Lapsed

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