USH557H - Epitaxial strengthening of crystals - Google Patents

Epitaxial strengthening of crystals Download PDF

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Publication number
USH557H
USH557H US06/927,993 US92799386A USH557H US H557 H USH557 H US H557H US 92799386 A US92799386 A US 92799386A US H557 H USH557 H US H557H
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US
United States
Prior art keywords
sub
crystal
epitaxial
laser
crystals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
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US06/927,993
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English (en)
Inventor
Robert C. Morris
II John E. Marion
Devlin M. Gaultieri
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United States, AS REPRESENTED BY UNITED DEPARTMENT OF ENERGY
US Department of Energy
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US Department of Energy
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Application filed by US Department of Energy filed Critical US Department of Energy
Priority to US06/927,993 priority Critical patent/USH557H/en
Assigned to UNITED STATES OF AMERICA, THE, AS REPRESENTED BY THE UNITED STATES DEPARTMENT OF ENERGY reassignment UNITED STATES OF AMERICA, THE, AS REPRESENTED BY THE UNITED STATES DEPARTMENT OF ENERGY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GUALTIERI, DEVLIN M., MORRIS, ROBERT C.
Assigned to UNITED STATES OF AMERICA, THE, AS REPRESENTED BY THE UNITED DEPARTMENT OF ENERGY reassignment UNITED STATES OF AMERICA, THE, AS REPRESENTED BY THE UNITED DEPARTMENT OF ENERGY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MARION, JOHN E. II
Priority to DE19873736731 priority patent/DE3736731A1/de
Priority to GB8725597A priority patent/GB2198056B/en
Priority to JP62280265A priority patent/JPH01123000A/ja
Priority to FR8715435A priority patent/FR2607833A1/fr
Priority to IT22555/87A priority patent/IT1223082B/it
Application granted granted Critical
Publication of USH557H publication Critical patent/USH557H/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B19/00—Liquid-phase epitaxial-layer growth
    • C30B19/02—Liquid-phase epitaxial-layer growth using molten solvents, e.g. flux
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • C30B29/22—Complex oxides
    • C30B29/28—Complex oxides with formula A3Me5O12 wherein A is a rare earth metal and Me is Fe, Ga, Sc, Cr, Co or Al, e.g. garnets
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure

Definitions

  • the invention relates to the properties of crystals, more particularly to the strengthening of crystals, especially for use in lasers.
  • Single crystals are used in a variety of applications such as in the electronics industry and in the optics industry. In the optical arts, single crystals are grown for laser media, laser amplifiers, harmonic conversion and other uses.
  • laser media single crystals are yttrium aluminum garnet (YAG), gadolinium gallium garnet (GGG), and gadolinium scandium gallium garnet (GSGG).
  • lasers must not only have high energy in a given laser pulse, but must also have a high repetition rate of those pulses.
  • laser media were predominately in two geometries: the rod for smaller sizes and the disk for larger sizes. Rods could be crystalline or glass, and larger sizes were made of glass. Due to its low thermal conductivity, glass cannot rapidly remove the heat generated during laser operation. Also, most crystals are inherently stronger than glass and have other desirable spectroscopic properties. Thus, crystals are the favored material for the new laser media.
  • slab type geometries are superior to the older rod geometries for high average power solid state layers.
  • the slab has large surface area to take off heat from the sides of the amplifier medium not in the laser beam, and at the same time can be formed from crystalline materials.
  • Current designs for high average power slab lasers have rectangular slab geometries with dimensions on the order of 1 by 10 by 20 centimeters in a single crystal garnet as shown in FIG. 1.
  • the laser media are placed under greater operating stress than ever before. These stresses arise from the temperature gradient in the slab. Absorption of flashlamp or other pumping energy leads to heating of the slab bulk. The active cooling of slab surfaces by high velocity fluids leads to a steady state thermal gradient within the slab. The thermal gradient gives rise to biaxial tensile stresses at the slab surfaces whose magnitude can approach or exceed the component strength.
  • strengthening a single crystal laser medium permits higher average power output.
  • One approach to strengthening has been to remove or minimize subsurface damage.
  • Subsurface damage has been shown to be removed by the methods of acid etching and by large amounts of material removal in the grinding and polishing fabrication steps. This method is reported in J. E. Marion, "Strengthening of Solid State Laser Materials", Appl. Phys. Lett., 47, pp 694-696 (1985) and is responsible for up to 15 times increase in crystal strength.
  • it has been difficult to fully implement this method because it has not been possible to preserve the pristine surfaces throughout the entire process of handling, mounting and use in the laser.
  • Epitaxial layers are presently applied to crystals for bubble memory and cathode ray tube applications. Unstrained layers are preferred for these applications.
  • the present invention utilizes epitaxial layers with intentionally high amounts of strain specifically to induce a compressive force and thus strengthen the crystal.
  • FIG. 1 is a "zig-zag" slab amplifier geometry in which the slab is pumped through the large faces and the extraction beam zig-zag through the slab by total internal reflection;
  • FIG. 2 is a graph strength of GGG substrates with, and without, repressive epitaxial layers as a function of surface abrasion treatment.
  • a mismatch in the relative size of the lattice spacings of the crystals are used.
  • the basic requirement is that the lattice spacing of the epitaxial crystal material be slightly larger than the lattice spacing of the substrate crystal to be strengthened.
  • a preferred method for achieving this is to dope the epitaxial material with a dopant having a larger lattice spacing than in the unsubstituted crystal. Otherwise the epitaxial material can be the same or similar material as the substrate.
  • the strain on the substrate surface has been found to be best in the 0.01% to 0.3% range with about 0.1% as the optimum. Strain is defined as substrate characteristic length subtracted from the corresponding epitaxial layer characteristic length divided by the substrate characteristic length. The characteristic length may be an average crystal lattice spacing.
  • the substrates were 111
  • wafers had small orientation flats in the 112
  • Epitaxial growth was performed in a class 100 clean hood.
  • the substrates were cleaned thoroughly with a mildly caustic cleaning solution and rinsed in deionized water before growth.
  • a supercooled lead oxide flux (see Table 1) was used for the liquid phase epitaxial growth using the isothermal dipping techniques with rotation (200 revolutions/minute) of the horizontally held substrates. For more on this well known technique see H. J. Levinstein, et al., Appl. Phys. Lett. 19, 486 (1971).
  • neodymium substituted GGG was grown on pure GGG substrates.
  • Neodymium has a larger ionic radius than gadolinium, and incorporation of Nd on Gd sites in the garnet gives a larger lattice constant.
  • the melt composition (Table 1) allowed a growth rate of about one micron per minute when supercooled by 15 degrees centigrade to the growth temperature of 895 degrees centigrade. Layers of about the same thickness are grown on each side of the substrate. Epitaxial growth under these conditions resulted in a strain mismatch between epitaxial layers and substrates of about 0.1%, giving the desired high compressive surface a stress of about 200 MPa.
  • Layer thickness was determined by the increase in weight after growth using a density of 7.068 g/cc with the assumption that layers of equal thickness were grown on each side of the substrate. Experience with bubble memory layers has shown the side to side thickness variation to be minimal (approximately 5%).
  • Lattice constant measurements of the substrate and layers were done with a Bond diffractometer (W. L. Bond, Acta Cryst. 13, 814 (1960); A31, 698 (1975). Using CuK sub alpha radiation, the (888) reflection was excited and the substrate diffraction pattern was superimposed on the epitaxial layer pattern. Since the diffraction measurements are influenced by the strain induced during growth, these measured lattice constants were corrected for strain using the expression:
  • the substrates were fractured in a ball-on disk-on 3-ball jig which gives equ-biaxial tension along the bottom surface.
  • untreated specimens from the same polishing lot were also broken.
  • the stress is related to the load by a relation given by J. B. Wachtman, Jr. et al, "Biaxial Flexure Tests of Ceramic Substrates", J. of Materials, 7, pp 188-194 (1972). All samples were fractured at a loading rate of 0.1 mm per minute.
  • the table 3 results for abrasion show the clear advantage of the present invention.
  • Abrasion with 6 micron diamond and indentation with a Vickers micro-hardness diamond indenter at 2N load did not substantially degrade the strength of the epitaxial layer substrates.
  • the bare substrates were decreased in strength by the abrasion treatment to a level that would be unusualbe in current laser designs.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
US06/927,993 1986-11-07 1986-11-07 Epitaxial strengthening of crystals Abandoned USH557H (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US06/927,993 USH557H (en) 1986-11-07 1986-11-07 Epitaxial strengthening of crystals
DE19873736731 DE3736731A1 (de) 1986-11-07 1987-10-29 Epitaxiale festigkeitserhoehung von kristallen
GB8725597A GB2198056B (en) 1986-11-07 1987-11-02 Epitaxial strengthening of crystals
JP62280265A JPH01123000A (ja) 1986-11-07 1987-11-05 結晶の強化方法および装置
FR8715435A FR2607833A1 (fr) 1986-11-07 1987-11-06 Renforcement epitaxial de cristaux
IT22555/87A IT1223082B (it) 1986-11-07 1987-11-06 Procedimento ed apparecchiatura per il consolidamento epitassiale di cristalli

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/927,993 USH557H (en) 1986-11-07 1986-11-07 Epitaxial strengthening of crystals

Publications (1)

Publication Number Publication Date
USH557H true USH557H (en) 1988-12-06

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US06/927,993 Abandoned USH557H (en) 1986-11-07 1986-11-07 Epitaxial strengthening of crystals

Country Status (6)

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US (1) USH557H (it)
JP (1) JPH01123000A (it)
DE (1) DE3736731A1 (it)
FR (1) FR2607833A1 (it)
GB (1) GB2198056B (it)
IT (1) IT1223082B (it)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5573862A (en) * 1992-04-13 1996-11-12 Alliedsignal Inc. Single crystal oxide turbine blades
US6122993A (en) * 1998-01-26 2000-09-26 Alliedsignal Inc. Isotropic energy storage flywheel rotor

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4401626A1 (de) * 1994-01-20 1995-07-27 Max Planck Gesellschaft Verfahren und Vorrichtung zur Herstellung kristalliner Schichten

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3964035A (en) 1974-09-23 1976-06-15 Bell Telephone Laboratories, Incorporated Magnetic devices utilizing garnet epitaxial materials
US4263374A (en) 1978-06-22 1981-04-21 Rockwell International Corporation Temperature-stabilized low-loss ferrite films
US4354254A (en) 1980-11-07 1982-10-12 Bell Telephone Laboratories, Incorporated Devices depending on garnet materials
US4434212A (en) 1980-07-11 1984-02-28 U.S. Philips Corporation Device for propagating magnetic domains
US4544239A (en) 1983-03-16 1985-10-01 Litton Systems, Inc. Compressed bismuth-containing garnet films of replicable low anisotropy field value and devices utilizing same
US4544438A (en) 1984-05-31 1985-10-01 At&T Bell Laboratories Liquid phase epitaxial growth of bismuth-containing garnet films
US4625390A (en) 1983-03-16 1986-12-02 Litton Systems, Inc. Two-step method of manufacturing compressed bismuth-containing garnet films of replicable low anisotropy field value

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1614574A1 (de) * 1967-08-04 1970-10-29 Siemens Ag Halbleiterbauelement,insbesondere Halbleiterbauelement mit pn-UEbergang
US3650737A (en) * 1968-03-25 1972-03-21 Ibm Imaging method using photoconductive element having a protective coating
US3821039A (en) * 1973-03-22 1974-06-28 Rca Corp Method of epitaxially depositing a semiconductor material on a substrate
US4188244A (en) * 1975-04-10 1980-02-12 Matsushita Electric Industrial Co., Ltd. Method of making a semiconductor light-emitting device utilizing low-temperature vapor-phase deposition
US4180825A (en) * 1977-09-16 1979-12-25 Harris Corporation Heteroepitaxial deposition of GaP on silicon substrates
NL7902293A (nl) * 1979-03-23 1980-09-25 Philips Nv Magnetische beldomein structuur en magnetische beldomeininrichting.

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3964035A (en) 1974-09-23 1976-06-15 Bell Telephone Laboratories, Incorporated Magnetic devices utilizing garnet epitaxial materials
US4263374A (en) 1978-06-22 1981-04-21 Rockwell International Corporation Temperature-stabilized low-loss ferrite films
US4434212A (en) 1980-07-11 1984-02-28 U.S. Philips Corporation Device for propagating magnetic domains
US4354254A (en) 1980-11-07 1982-10-12 Bell Telephone Laboratories, Incorporated Devices depending on garnet materials
US4544239A (en) 1983-03-16 1985-10-01 Litton Systems, Inc. Compressed bismuth-containing garnet films of replicable low anisotropy field value and devices utilizing same
US4625390A (en) 1983-03-16 1986-12-02 Litton Systems, Inc. Two-step method of manufacturing compressed bismuth-containing garnet films of replicable low anisotropy field value
US4544438A (en) 1984-05-31 1985-10-01 At&T Bell Laboratories Liquid phase epitaxial growth of bismuth-containing garnet films

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5573862A (en) * 1992-04-13 1996-11-12 Alliedsignal Inc. Single crystal oxide turbine blades
US6122993A (en) * 1998-01-26 2000-09-26 Alliedsignal Inc. Isotropic energy storage flywheel rotor

Also Published As

Publication number Publication date
IT1223082B (it) 1990-09-12
JPH01123000A (ja) 1989-05-16
GB2198056B (en) 1990-09-26
GB2198056A (en) 1988-06-08
DE3736731A1 (de) 1988-05-11
FR2607833A1 (fr) 1988-06-10
IT8722555A0 (it) 1987-11-06
GB8725597D0 (en) 1987-12-09

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