US3716405A - Vapor transport method for growing crystals - Google Patents

Vapor transport method for growing crystals Download PDF

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US3716405A
US3716405A US00078445A US3716405DA US3716405A US 3716405 A US3716405 A US 3716405A US 00078445 A US00078445 A US 00078445A US 3716405D A US3716405D A US 3716405DA US 3716405 A US3716405 A US 3716405A
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crystal
gallium
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M Lim
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AT&T Corp
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Western Electric Co Inc
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
    • H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
    • H10H20/80—Constructional details
    • H10H20/81—Bodies
    • H10H20/822—Materials of the light-emitting regions
    • 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
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/14—Feed and outlet means for the gases; Modifying the flow of the reactive gases
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/02521—Materials
    • H01L21/02538—Group 13/15 materials
    • H01L21/02543—Phosphides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/0257—Doping during depositing
    • H01L21/02573—Conductivity type
    • H01L21/02579—P-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02518—Deposited layers
    • H01L21/0257—Doping during depositing
    • H01L21/02573—Conductivity type
    • H01L21/02581—Transition metal or rare earth elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
    • H01L21/02612—Formation types
    • H01L21/02617—Deposition types
    • H01L21/0262—Reduction or decomposition of gaseous compounds, e.g. CVD
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/056—Gallium arsenide
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/064—Gp II-VI compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/065—Gp III-V generic compounds-processing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/119—Phosphides of gallium or indium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/122—Polycrystalline
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S438/00—Semiconductor device manufacturing: process
    • Y10S438/914—Doping
    • Y10S438/925—Fluid growth doping control, e.g. delta doping
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S438/00—Semiconductor device manufacturing: process
    • Y10S438/935—Gas flow control

Definitions

  • Single crystals of either III-V or II-VI compounds are deposited on a heated substrate using a heated liquified mass of the metallic constituent (Group III or II), a hydrogen compound of the Group V or VI element and wet hydrogen as source materials within an open reaction tube at an elevated temperature.
  • single crystal GaP is grown using heated liquid gallium (Ga), phosphine (EH and wet hydrogen (H and H as source materials.
  • the wet hydrogen is passed over the liquid gallium to generate a gallium sub-oxide (Ga O) stream while the temperature of the tube decomposes the phosphine to P and H in a stream.
  • the P and Ga o-containing streams are mixed but they reach the heated substrate whereat the single crystal gallium phosphide is grown.
  • Thermodynamic analysis yields permissible ranges for the partial pressures of the P the Ga O, and H 0 (from which are derived the inlet pressures of the PH and the H O+H and for the temperature of the liquid Ga and of the substrate.
  • Uniform, large area single crystals (e.g., GaP) grown in this manner contain high amounts of electrically active dopants (e.g., oxygen) and are usable as efiicient photoand electro-luminescent devices.
  • the present invention relates to growing or synthesizing crystals and, more specifically, both to methods of growing single crystals or synthesizing polycrystalline material by a vapor transport method and to the crystals grown by such methods.
  • the present invention contemplates, inter alia, so called vapor phase epitaxy (VPE) production methods, that is, growing single crystals or crystalline material from a vapor phase of the constituents thereof onto an appropriate seed or substrate.
  • VPE vapor phase epitaxy
  • the present invention also contemplates nonepitaxial vapor phase production methods, that is, the synthesis of polycrystalline material from a vapor phase of the constituents thereof with or without the use of a seed or substrate.
  • Such crystals of either type may be a so called III-V or -II-V compound. If the crystal is epitaxially grown (a single crystal) and is a III-V or lI-VI compound it may be semiconductive, electroluminescent and photoluminescent.
  • the present invention is not necessarily limited, however, to the growth of potential semiconductive, electroluminescent, photoluminescent single crystals, but contemplates the growth or synthesis from the vapor phase of many other types of single crystals and polycrystals.
  • Crystals of many difierent types are widely used for a variety of purposes. When such crystals are single crystals, they may, with proper doping, be used to manufacture semiconductive, electroluminescent diodes and other devices such as dynodes (light amplifiers). When the crys- 3,716,405 Patented Feb. 13, 1973 tals are polycrystalline, they may be used as starting products in other processes of growing single crystals.
  • gallium phosphide [GaP] gallium arsenide [GaAs], gallium arsenide-phosphide [GaAs P gallium aluminum-arsenide or silicon carbide are, when properly doped, some of the most efiicient light sources presently known.
  • such diodes are made of a single crystal, such as gallium phosphide, which includes a p-n junction.
  • the crystal must be doped, typically, in the case of red lightemitting gallium phosphide with oxygen and zinc (p-type) or with tellurium, selenium or sulphur (n-type).
  • the oxygen dopant when properly incorporated into the crystal, is substituted at phosphorus sites, while the zinc, similarly incorporated, is substituted at gallium sites to form nearest neighbor zinc-oxygen complexes in the lattice of the crystal.
  • Green light-emitting gallium phosphide con tains p-type material doped with nitrogen. The nitrogen dopant is isoelectronically substituted at phosphorus sites.
  • Forward biasing of the p-n junction injects electrons from the n-side into the p-side whereat some electrons are trapped by the zinc-oxygen complex, in the case of red light-emitting Gal.
  • the trapped electrons subsequently trap, or recombine with, holes to produce an exiton resulting in the emission of characteristic radiant energy.
  • Such radiant energy in the case of the zinc-oxygen dopants in gallium phosphide, is in the red portion of the visible spectrum.
  • electroluminescence of these diodes is due to the band-gap of the crystals being large enough to encompass the visible radiation spectrum. That is, electroluminescence is caused by an electron-hole recombination mechanism.
  • the constituents of semiconductive, electroluminescent crystals are usually compounds selected as follows:
  • the above-described single crystals exhibit electroluminescence only upon the proper inclusion therein of appropriate dopants.
  • a single crystal of GaP contains substantial amounts of substitutional oxygen and zinc, it electroluminesces in the red region of the visible spectrum.
  • a different dopant for example nitrogen, results in a single crystal which may electroluminesce in the green region of the visible spectrum.
  • an impurity is any substance which, when incorporated into a crystal, affects its electrical, physical, chemical, etc., properties in some undesired fashion.
  • a dopant is similar to an impurity but is intentionally incorporated in small amounts into the crystal to effect some desired property therein.
  • oxygen and zinc intentionally incorporated into a single crystal which is intended to electroluminesce in the red region of the visible spectrum, are dopants.
  • Oxygen incorporated into a single crystal ultimately intended to electroluminesce in the green region of the visible spectrum may be an impurity.
  • Electroluminescent diodes and other devices made from single crystals of the IIIV or II-VI compounds are more sturdy, reliable and longer-lived than, and are accordingly replacing, conventional incandescent lamps in a number of applications. Additionally, such diodes and devices are compact, compatible with solid state circuitry and require very little power for operation.
  • crystals may be grown by a crystal pulling method from a stoichiometric or near-stoichiometric melt.
  • Present crystal pulling methods have been found to be deficient for a number of reasons. Among these reasons are the necessity of high pressures (30-40 atm.), high temperatures (about 1500 C.) and facilities sufliciently elaborate to permit such high pressure and temperature; the unwanted introduction of impurities from crucibles at the pressure and temperature necessarily utilized; and the inability to consistently grow high quality crystals. Further, in many difficult-to-predict situations, the uniform incorporation of many dopants into crystals produced by the pulling method has proved difficult. Gallium phosphide single crystals grown by a liquid-encapsulationpulling method so far have not been successfully usable in electroluminescent diodes.
  • the crystals may be grown from solutions by either so called liquid phase epitaxy (LPE) or by so called solution growth.
  • LPE liquid phase epitaxy
  • a heated, liquid phase of the constituents of the desired crystal is made to cool by slowly lowering the temperature thereof (which effects super-saturation).
  • Such slow lowering of the temperature encourages the growth of single crystals while discouraging the growth of polycrystals.
  • the method is liquid phase epitaxy (LPE); when a substrate or seed is not used and the crystal growth is manifested by the random production at separated sites of single crystals within the solution, the solution growth method is being used.
  • seed and substrate are used interchangeably herein. As is well known, if a crystal layer to be grown is a single crystal layer, it is necessary that the seed or substrate also be a single crystal. If polycrystal layer growth is desired, it is not necessary that the seed or substrate be a single crystal.
  • the third prior art method used to produce single crystals is a vapor transport epitaxial growth method.
  • present vapor transport growth methods are unable to properly incorporate, in sufiicient quantities, dopants, such as oxygen, into the grown crystals.
  • dopants when properly incorporated into substitutional sites of the crystal and which contribute to the photoor electroluminescence, are termed electrically active.
  • electrically active dopants usually substitutional (desirable) and dopants which are merely interstitial in nature. The latter do not improve, and may degrade a crystals electroluminescent and other properties.
  • the more electrically active dopant incorporated properly into a single crystal the more efficient that crystal is as an electroluminescent light source. It is desirable that an efiicient vapor transport method of growing high efiiciency electroluminescent single crystals having therein proper amounts of electrically active dopants be found. Such is accordingly another object of the present invention.
  • the present invention is an improvement of this third type of prior art method, namely the growth of crystals from the vapor phase of the constituents thereof, and the relaization of such an improved method is accordingly an additional object of this invention.
  • vapor phase growth should be more expedient than crystal pulling or solution methods.
  • vapor phase growth provides more convenient control over the thickness of a grown crystal layer.
  • vapor transport methods have been found to have the ability to produce large-area, uniform thin crystal layers, thinness being an advantage from the standpoint of the ultimate electrical use of the grown crystal as an electroluminescent light source.
  • additional objects of this invention are to provide an improved method of vapor phase crystal growth which eliminates the short-comings of prior artmethods and which takes advantage of the inherently easier control of crystal layer thickness provided by such a method.
  • the first method is a halide transport method; the second method involves the decomposition, in the presence of water vapor, of a polycrystalline compound into its constituents (in a vapor phase) followed by the transport and deposition of the constituents onto a seed or substrate.
  • halides of the crystals constituents for example a Group III element such as gallium and a Group V element such as phosphorus, are transported in a heated state to a cooler substrate or seed whereat crystalline growth occurs.
  • a crystal compound such as gallium phosphide having a light-emitting efficiency approaching zero.
  • dopants e.g., oxygen
  • single crystals grown by the halide transport method have been primarily used for substrate or seed materials in LPE methods.
  • another object of the present invention is to provide a novel method of growing efficient electroluminescent single crystals by methods as simple as, but more expedient than, prior art halide transport methods.
  • dry hydrogen passes over a dopant source (e.g., zinc) located in an open heated reaction tube, if it is desired to grow an electroluminescent compound.
  • a dopant source e.g., zinc
  • the wet hydrogen first passes over a heated source of a polycrystalline compound of the constituents of the crystal it is desired to grow.
  • this heated source may be a heated mass of polycrystalline gallium phosphide.
  • the wet hydrogen stream passes over the heated constituent source, the polycrystalline phase volatilizes and is entrained in the stream.
  • the wet hydrogen now combines with the dry hydrogen, containing portions of the dopant source and the mixture impinges on the substrate or seed where, due to a maintained temperature difference, a single crystal layer (appropriately doped) grows.
  • a specific temperature profile must be maintained within the furnace. Specifically, the constituent source must be maintained at the high temperature end of the temperature profile (about 1100 C.). The substrate must be maintained at a lower temperature. The temperature gradient so produced drives the chemical system into nonequilibrium whereat crystals are grown. It is absolutely necessary that such a temperature gradient be maintained.
  • VPE vapor phase epitaxy
  • an object of the present invention is to provide an improved transport method using water vapor which permits the proper incorporation of dopants into grown crystal layers which can then be used in the production of high etficiency electroluminescent diodes.
  • the second transport method is marked by a lack of freedom in adjusting the methods parameters.
  • the necessity of a predetermined temperature profile has been already noted.
  • the source is polycrystalline GaP
  • the partial pressures of gaseous Ga O and gaseous P are the same and are not independently variable. Elimination of this lack of freedom is yet a further object of this invention.
  • a further object of this invention is the provision of a method having the ability to produce, on a continuous basis, p-type and n-type compounds to form a p-n junction;
  • the present invention contemplates a new and improved method of growing single crystal or synthesizing polycrystalline materials and, more specifically, to a new and improved method of growing such crystals by a vapor phase transport method.
  • the present invention also contemplates new and improved crystalline compounds produced by the method of this invention.
  • the species considered in factors (1) to (3) are combeined together in a hydrogen environment at a heated substrate or seed in the gaseous phase to grow the crystal.
  • the evolution of the equilibrium system is such that undesirable species are not present or are present in negligible amounts at the seed or substrate.
  • any two of the factors (1)-(3) can be varied over a broad range of values to grow the crystals; such variation causes the third factor to assume a value which remains, like the other two factor values, within deviation limits of a hypothesized equilibrium system.
  • the system in order to grow a crystal, the system must be driven into non-equilibrium. When such is done, due to the character of the system, undesirable species are not present.
  • Non-equilibrium may be effected by holding two of the factors (1)-(3) constant and varying the third in a favorable direction.
  • the Group II or III element is gallium, from Group III; the Group V or VI element (factor (2)) is phosphorus, from Group V; and the factor 3) is H O.
  • the oxygen-containing compound of gallium is gallium sub-oxide, specifically, Ga O.
  • Present at a subtraste or seed are the gaseous species of pages printe in t e ht From Semiconductors by etherla ax R. Lorenz in ce, Mar. 29, 19 8, v0 ume umber 3822, pages 14191423; Solid State Light, by N N M g S. Epstein and Holonyak in Science Journal, Janua y 1969, pages 68-73; The Epitaiiial Growth of GaP W [7W mmyw/llrclzmm 11 a 1, mm
  • the transport line 43 inserted through the plug 38b has its exit end 52 positioned adjacent the substrate or seed 22 in the holder 48. As shown by the arrows 54, a gas stream emitted from the exit end 52 impinges upon the held substrate or seed 22.
  • a second transport line 45 has its exit end 56 positioned near a boat or dish-like container 58. As shown by the arrows 60, gases emitted from the exit end 56 of the transport line 45 impinge on the surface of a liquid mass 62. After impinging on the liquid mass 62, the gas stream passes upstream where it impinges on the held substrate or seed 22. With respect to the direction of the gas streams emitted by the line exits 52 and 56, the exit end 52 is upstream from the exit end 56.
  • Such relative location and other standard techniques such as the maintenance of the flow within the tube by the exhaust port 40 may be ?utilized to prevent substantially all mixing of the gas streams emitted from the exits 52 and 56 prior to their concurrent arrival at the space 65 between the exit 52 of the transport tube 43 and the held substrate or seed 22. Although somewhat premature, it should be noted that while the gas streams do mix in the space 65, no reaction thereof takes place. As explained below, the chemical system within the reaction tube 34 permits reactions to occur around the held substrate 22.
  • a third transport line, 44 has its exit end 66 positioned near the held substrate 22. As shown by the mottled shading 67 within the space 65, gases emitted by the exit end 66 are mixed, directed and impinge on the held substrate 22. Such gases contain an appropriate dopant in the vapor phase, for incorporation into the grown crystal layer 21 (FIG. 1).
  • the line 44 is either connected to a source of .a gaseous dopant, e.g., dimethyl zinc, or contains a boat 68 holding a mass 69 of the dopant. In the latter case, the elevated temperature of the tube 34 generates a vapor phase of the dopant mass 69 (as shown'by the cloud 70) which is entrained in a carrier gas (arrows and carried into the space 65.
  • the transport line 43 has its input connected to sources (not shown) of a gas mixture comprising a source of a gaseous form of the Group V or VI element to be used, e. g., phosphine and a diluent gas, such as hydrogen.
  • sources e. g., phosphine and a diluent gas, such as hydrogen.
  • Standard gas flow regulations may be passed in series with the various sources to selectively vary the relative proportions of the gases emitted by the exit end 52.
  • the diluent gas is hydrogen (H the Group V or VI element is phosphorus, compounded with hydrogen as phosphine (PH After entry into the line 43 the phosphine is decomposed by the high temperature of the reaction tube 34, into phosphorus (P and hydrogen (H).
  • the gas stream 54 is P +H
  • concentration of P is, of course, selectively variable by control of the regulators. As explained later, the P (or other Group V or VI gaseous element) concentration is determined by thermodynamic considerations.
  • the transport line 45 has its input connected to sources (not shown) of a carrier gas and a source of water vapor capable of forming a gaseous oxide of the selected Group H or III element.
  • Standard gas flow regulators may be placed inseries with the various sources to selectively vary the relative proportions of the gases emitted by the exit end 56.
  • the carrier gas is again hydrogen (H
  • H may be purified in a palladium-silver diffusion purifier (not shown) and then humidified to saturation by bubbling through a H O bath (not shown) at a constant temperature.
  • the humidified hydrogen is then passed through a standard condenser (not shown), maintained at a constant temperature, whereby the hydrogen is saturated with water vapor.
  • H +H O mixture leaves the exit end 56 in the gas stream 60.
  • concentration of H 0 is, of course, selectively variable by control of the condenser temperature and the flow rate of hydrogen. As explained later, the H 0 concentration is determined by thermodynamic considerations.
  • the gas stream 60 impinges on the surface of the liquid mass 62 in the boat 58. Due to the temperature of the reaction tube 34, both the stream 60 and the mass 62 are heated. As the stream 60 passes over the mass 62, a reaction between the H 0 in the stream 60 and the mass 62 produces an oxide of the mass 62.
  • the liquid mass is gallium (Ga) and the sub-oxide thereof is Ga' O-
  • the gas stream 64 contains H H 0, and Ga O (plus possible traces of other oxides, e.g., GaO).
  • the amount of H 0 and Ga O in the stream 64 is selectively adjusted by control of the flow rate and by the temperature of the liquid gallium mass 62 and the H 0 concentration of the gas stream 60. These amounts, as explained below, are determined by thermodynamic considerations.
  • the space 65 Present in the space 65, then, are gaseous species of H 0, Ga O, and P as well as Zn. It is assumed that the amount of Zn dopant is so low as not to affect significantly subsequent chemical reactions which grow the GaP layer 21. Specifically, proper temperature control effects growth of the GaP layer 21 by the reaction Within limits, explained below, the partial pressures of the Ga O, the P and the H 0 at the substrate 22 are independently variable. Variation of these partial pressures has an effect on the amount of electrically active oxygen in the crystal layer 21 and also an effect on the growth rate of the layer 21. It should be pointed out that, unlike the prior art where a GaP source is used, the ability to independently vary these partial pressures makes possible:
  • a given temperature profile must be used. Specifically, the substrate must be maintained at a temperature lower than the GaP source.
  • use of gaseous P and Ga O as sources permits a wide range of permissible temperature profiles within the tube 34. It has been found that the only real restriction on the temperature profile 15 that it must be one which reduces the possibility bf a reaction between the gaseous species present before they reach the substrate 22.
  • T is the temperature of the liquid Ga mass 62
  • T is the temperature in the space 65
  • T is the temperature of the substrate 22.
  • Profiles (b)-(d) are preferred, and these profiles have proved especially effective in preventing reactions between the Ga O,- H 0, and P in the space 65 especially those reactions which deposit material from the streams 54 and 64 on the walls of the tube 34 (as well as on the exit end 52 of the line 42).
  • T may range from about 700 C. to at least about 1200 C.
  • T may range from about 900 C. to about at least about 1200 C.
  • reaction (1) As previously noted the reaction at the substrate 22 is reaction (1) given above.
  • the 621 in the stream 64 is generated by the following reaction at the boat 58:
  • H Ol H Ol
  • H 0 in Equation 2 H 0 in Equation 2
  • growth of the crystal layer 21 may be effected by driving the system in a favorable direction.
  • driving may be effected by:
  • FIG. 3 there is shown a general graph, the area within which defines a stable chemical system labelled I at the substrate 22 which defines the area of permissible growth of the layer 21.
  • the Y- axis of the graph is the partial pressure of Ga O on a log sc'ile; the X-axis is the partial pressure of P on a log sc e.
  • line segments II, III, and IV forming the graph are derived as follows:
  • the X-intercept of the vertical line II can be determined.
  • the X-intercept 102 of the point of intersection of the segments III and IV can be located.
  • the area I may be defined. At the temperature T and anywhere in the area 1, crystal layers 21 may be grown without the production of undesirable species which are deleterious to the efiicient operation of the crystal. Also within the area I, proper amounts of electrically active dopants are incorporated into the crystal layer 21.
  • line segments II and IV do not terminate at the X-axis, which is arbitrarily chosen for purposes of illustration, but extend downwardly in FIG. 3 to infinity. However, such extension may place the Ga O partial pressure (Y-axis value) at very low values (less than about l 10- atrn.) whereat crystal growth is impractically slow, as is well known.
  • the line segments H, III, and IV bounding the area I have real chemical and thermodynamic meaning. Without going into undue detail, sufiice it to say that GaP grown within the boundaries of the enclosed area I is acceptable single crystal GaP, while GaP grown outside thereof is not. Such unacceptability is due to the fact that outside the area, improper species of the constituents of GaP are present.
  • FIG. 4 there is shown a graph similar to FIG. 3 except that a family of contour lines 103 (dotted) have been added to represent, within the area I of desirable growth, permissible partial pressures of the H O-l, that is, the H 0 at the substrate 22 during the reaction of Equation 1. These H O lines are parallel to the line segment IV and, thus, have a slope of -1.
  • FIG. 5 is a graph of Ga O partial pressure (log scale X-axis) versus H O partial pressure (log scale Y-axis) both at the substrate 22. To derive a line 104 representingrthe temperature T of the substrate 22, the following is performed:
  • the Y-intercept such as that represented by a point 106 in FIG. 5, may be calculated.
  • Theco-ordinate of points 105 and 106 i.e., the point (105, 106)
  • the lines 104 are known to have a slope of +1.
  • the point 107 and this slope determine the line 104.
  • the remainder of the lines 104 in FIG. 5 are generated in this same manner. Further, then, the family of H20-].
  • contour lines 103 in FIG. 4 may be generated at any temperature T.
  • FIG. 6 is a graph similar to FIG. 4 for a T of 1050 C. of the substrate 22.
  • FIG. 7 shows, on the same axes, three graphs similar to FIG. 4 for temperatures T of 950 C., 1050 C., and 1100 C., respectively.
  • the Y-intercepts 101 are found to lie on a straight line 110;the points of intersection of segments III and IV are found to be on a straight line 111.
  • the lines 110 and 111 meet at a point 112, Where the area I is bounded only by the segments II and 'IV.
  • the temperature T for this area I is about 1142" C. Above this temperature, the considerations, above, are still used to determine the area I, but the positions of segments IH and IV are reversed from their positions in FIGS. 4-6.
  • the partial pressures of any of the following may be independently adjusted within the stability limits shown in FIG. 4: Ga- O, H 0, and P
  • Such independent adjustment via the apparatus of FIG. 2 within the boundaries of the area I of preferred growth of FIG. 4 permits the growth of single crystal layers 21 on the substrate 22.
  • any of the Ga O, P or H O partial pressures are adjusted to fall within the area I enclosed by the segments II, III, and IV. 5
  • no crystals are grown by a system in equilibrium in accordance with the principle of microscopic reversibility.
  • the system must be driven into nonequilibrium to grow the crystal layers 21.
  • H 0 partial pressure i.e., H201
  • reaction (1) proceeds in the forward direction at a reasonable rate.
  • a rate is one which avoids polycrystal growth (unless such growth is desired) and which does not produce undesirable species, such as gallium liquid, Ga O solid or GaPO solid.
  • point X represents an equilibrium system within the area I.
  • the point X can be defined, e.g., by known values for the partial pressures of Ga O and H 0 at the substrate 22. Of course the partial pressure of P at point X (per reaction (1)) in equilibrium is determined.
  • a favorable deviation of P form point X will grow a crystal layer 21 on the substrate 22.
  • Such a favorable deviation is a P partial pressure greater than that a point X and less than that represented by the intersection of a line 120 parallel to the X-aXis and segment IV or III, i.e., the right-hand stability limit of area I.
  • a favorable deviation of Ga O is between Ga O at X and Ga O at the point of intersection of a line 121 parallel to the Y- axis and line segment III or IV, i.e., the upper stability limit of area I.
  • All of the crystal layers 21 were single crystals, having relatively smooth surfaces, high densities (evidenced by slow etch rates), and high photoluminescence (13%) and electroluminescent efliciencies.
  • P-TYPE OXYGEN AND ZINC DOPED GaZO pres- H2O pres- 5% PHs-lsure at sure at 1110 tem- 95% Hz, substrate substrate Zinc presperature Ha-l-Hzo input Dry Hz H2+Zn atm. 10- P2 pressure atm. 10- sure at I a at input, nput flow flow, input flow input now, except as at substrate except as substrate Example No. ccJmin era/min. ee./min. ccJmin. shown atm. 10- shown atm.
  • N-TYPE (UNDOPED) 20.0 300.0 25.0 75.0 0.0 1.00 1.56 7.28 0.0 0. 0 300. 0 25. 0 75. 0 0. 0 2. 89X10- 1. 55 1. 64 0. 0 0. 0 0 25. 0 75. 0v 2. X10' 1. 55 1. 67 0. 0
  • the growth rate ranged, in all cases, from 1 fLlTL/hfr- 50 tm./hr., and was found to be dependent on both P and Ga o partial pressure, with approximately first order dependence residing in the P partial pressure.
  • the layers 21 ranged in thickness of up to 10 mils. on substrates 22 of %"-l" in diameter.
  • said first stream is produced by: decomposing phosphine PH said first stream comprising phosphorus P and hydrogen H 3.
  • said second tempera ture is within the range 700 6-1200 C.
  • said mixing step is effected by producing said first stream at a point intermediate said substrate and" a point whereat said second 16 bounded by the graph of FIG. 3; having an X-axis of the partial pressure of said P on a log scale and'a Y-a'xis of the partial pressure of said Ga' O on a log scale.
  • said area I is bounded by, and said graph consists of three intersecting line segments;
  • a first of said segments II has a slope of co and an X-intercept at a first point
  • a second of said segments IV has a slope of and a Y-intercept at its intersection with said first segment II at a second point;
  • said first point is defined by the equation Log partial pressure of P
  • said second point is defined by the equation Log partial pressure of Ga O
  • said third point is defined by the equation where T'is said elevated temperature of said substrate in degrees.
  • the method of claim 13 which includes the additional step of: directing at said substrate a stream containing a gaseous species of a dopant.
  • step (f) mixing said first and second streams and simultaneously preventing said first and second streams from reacting until they reach said substrate whereat the crystall is grown in a layer thereon by the reaction of said gaseous species of the one or more elements in step (b) and said first compound.
  • the Group H element is a metallic element selected from the group consisting of Zn and Cd;
  • the Group VI element is selected from the group consisting of O, S, Se, and Te;
  • the Group III element is a metallic element selected from the group consisting of Al, Ga, In, and T1;
  • the Group V element is N, E, As, Sb, or Bi.
  • said preventing step is effected by producing said first gaseous stream at a point intermediate the substrate and a point whereat said second gaseous stream is produced and by maintaining a flow direction of both of said streams in the direction of the substrate from said production points.
  • said mass is liquid gallium
  • said element in said first gaseous stream is P said compound is Ga and sadi layer is single crystalline GaP, grown according to the reaction 22.
  • the method of claim 21 wherein: the partial pressures of said H O, P and Ga O Within said reaction tube at said substrate fall within the area I bounded by the graph of FIG. 3.
  • said first temperature is within the range 700 C.-
  • said second temperature is within the range 900 C.-
  • a method of growing a gallium phosphide GaP crystal by the vapor transport of the constituents of the crystal comprising the steps of:
  • said area I is bounded by, and said graph consists of three intersecting line segments;
  • a first of said segments H has a slope of co and an X-intercept at a first point
  • a second of said segments IV has a slope of and a Y-intercept at its intersection with said first segment II at a second point;
  • a third of said segments III has a slope ,of 1 and an X-intercept at its point of intersection with said second segment IV at a third point;
  • said first point is defined by the equation Log partial pressure of P
  • T is said elevated temperature of said substrate in degrees.
  • the GaP crystal of claim 31 which is a single crystal.
  • the method of claim 30 which includes the addition step of: directing at said substrate a stream containing a gaseous species of a dopant.
  • the GaP crystal of claim 35 which is a single crystal.
  • said mixing step is efiected py producing said first stream at a point intermediate said substrate and a point whereat said second stream is produced, and by maintaining the flow direction of both streams in the direction of said substrate from said production points.

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3901746A (en) * 1970-02-27 1975-08-26 Philips Corp Method and device for the deposition of doped semiconductors
US3964940A (en) * 1971-09-10 1976-06-22 Plessey Handel Und Investments A.G. Methods of producing gallium phosphide yellow light emitting diodes
US4001056A (en) * 1972-12-08 1977-01-04 Monsanto Company Epitaxial deposition of iii-v compounds containing isoelectronic impurities
US4063974A (en) * 1975-11-14 1977-12-20 Hughes Aircraft Company Planar reactive evaporation method for the deposition of compound semiconducting films
US4253887A (en) * 1979-08-27 1981-03-03 Rca Corporation Method of depositing layers of semi-insulating gallium arsenide
US4316430A (en) * 1980-09-30 1982-02-23 Rca Corporation Vapor phase deposition apparatus
US4468850A (en) * 1982-03-29 1984-09-04 Massachusetts Institute Of Technology GaInAsP/InP Double-heterostructure lasers
US6303403B1 (en) * 1998-12-28 2001-10-16 Futaba Denshi Kogyo, K.K. Method for preparing gallium nitride phosphor
CN110854013A (zh) * 2019-11-11 2020-02-28 中国科学院金属研究所 一种大面积连续超薄二维Ga2O3非晶薄膜的制备方法与应用

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2358044C1 (ru) * 2007-09-20 2009-06-10 Общество с ограниченной ответственностью "Галлий-Н" Устройство для выращивания кристаллов

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3901746A (en) * 1970-02-27 1975-08-26 Philips Corp Method and device for the deposition of doped semiconductors
US3964940A (en) * 1971-09-10 1976-06-22 Plessey Handel Und Investments A.G. Methods of producing gallium phosphide yellow light emitting diodes
US4001056A (en) * 1972-12-08 1977-01-04 Monsanto Company Epitaxial deposition of iii-v compounds containing isoelectronic impurities
US4063974A (en) * 1975-11-14 1977-12-20 Hughes Aircraft Company Planar reactive evaporation method for the deposition of compound semiconducting films
US4146774A (en) * 1975-11-14 1979-03-27 Hughes Aircraft Company Planar reactive evaporation apparatus for the deposition of compound semiconducting films
US4253887A (en) * 1979-08-27 1981-03-03 Rca Corporation Method of depositing layers of semi-insulating gallium arsenide
US4316430A (en) * 1980-09-30 1982-02-23 Rca Corporation Vapor phase deposition apparatus
US4468850A (en) * 1982-03-29 1984-09-04 Massachusetts Institute Of Technology GaInAsP/InP Double-heterostructure lasers
US6303403B1 (en) * 1998-12-28 2001-10-16 Futaba Denshi Kogyo, K.K. Method for preparing gallium nitride phosphor
CN110854013A (zh) * 2019-11-11 2020-02-28 中国科学院金属研究所 一种大面积连续超薄二维Ga2O3非晶薄膜的制备方法与应用

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GB1362827A (en) 1974-08-07
CH583587A5 (enrdf_load_stackoverflow) 1977-01-14
FR2110956A5 (enrdf_load_stackoverflow) 1972-06-02
IT944725B (it) 1973-04-20
NL7113423A (enrdf_load_stackoverflow) 1972-04-07
BE773445A (fr) 1972-01-31

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