Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/448—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for generating reactive gas streams, e.g. by evaporation or sublimation of precursor materials
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/26—Deposition of carbon only
  • C23C16/27—Diamond only
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
  • C23C16/26—Deposition of carbon only
  • C23C16/27—Diamond only
  • C23C16/278—Diamond only doping or introduction of a secondary phase in the diamond
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/48—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating by irradiation, e.g. photolysis, radiolysis, particle radiation
  • C23C16/482—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating by irradiation, e.g. photolysis, radiolysis, particle radiation using incoherent light, UV to IR, e.g. lamps
• • 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
  • C30B25/10—Heating of the reaction chamber or the substrate
  • C30B25/105—Heating of the reaction chamber or the substrate by irradiation or electric discharge
• • 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
  • C30B29/02—Elements
  • C30B29/04—Diamond
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/24—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials using chemical vapour deposition [CVD]
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/29—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials characterised by the substrates
  • H10P14/2901—Materials
  • H10P14/2902—Materials being Group IVA materials
  • H10P14/2903—Carbon, e.g. diamond-like carbon
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/34—Deposited materials, e.g. layers
  • H10P14/3402—Deposited materials, e.g. layers characterised by the chemical composition
  • H10P14/3404—Deposited materials, e.g. layers characterised by the chemical composition being Group IVA materials
  • H10P14/3406—Carbon, e.g. diamond-like carbon
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/20—Formation of materials, e.g. in the shape of layers or pillars of semiconductor materials
  • H10P14/34—Deposited materials, e.g. layers
  • H10P14/3438—Doping during depositing
  • H10P14/3441—Conductivity type
  • H10P14/3442—N-type

Definitions

• the present invention relates to a low-resistance ⁇ -type half-body diamond doped with both lithium and nitrogen and a method for manufacturing the same. More specifically, lithium atoms are doped at interstitial positions of carbon atoms in a diamond single crystal, and nitrogen atoms are doped at substitution positions of carbon atoms, and they have adjacent structures. Further, the present invention relates to a method for producing the low-resistance ⁇ -type semiconductor diamond of the present invention by a gas phase synthesis method by a gas phase synthesis method by photo-decomposing a raw material using vacuum ultraviolet light. Background art
• Diamond has a very large band gap of 5.5 eV, and there is no intrinsic region where the conduction of carriers as a semiconductor becomes uncontrollable at 140 (TC or lower. Since it is as small as 7, the breakdown electric field is as large as 5 ⁇ 10 6 V ⁇ cm-1 1.
• the carrier mobility is as high as 2000 cm 2 / V-s for both electrons and holes at room temperature.
• a semiconductor device made of diamond having such an electrical characteristic a power device that can withstand high frequency and high output operation at high temperature and ultraviolet light emission are also used. A light emitting device that can be used or an electron emission device that can be driven at a low voltage can be expected.
• a p-type semiconductor diamond can be obtained by adding boron as an impurity to a diamond crystal.
• P-type semiconductor diamond also exists in nature and can be synthesized relatively easily by introducing a gas containing boron atoms into the source gas by chemical vapor synthesis (CVD).
• n-type semiconductor diamond does not exist in nature and has been synthesized
• phosphorus or yeo as a dopant
• a single crystal n-type semiconductor diamond with relatively good crystallinity has been obtained. Have been obtained.
• a pn junction is formed and a prototype of an ultraviolet light emitting device is manufactured. Is being done.
• the n-type semiconductor diamond doped with phosphorus or zeolite which has the best performance among the single-crystal n-type semicrystalline diamonds with good crystallinity, has a » ⁇ rate of 10 4 ⁇ at room temperature. ⁇ It is about cm, and has higher resistance than other semiconductor materials.
• the activation energy of these n-type semiconductor diamonds is as large as about 0.6 eV when phosphorus is doped, and about 0.4 eV when diode is doped. The temperature dependence is large, and it is difficult to use devices using these n- type semiconductor diamonds stably over a wide temperature range.
• the covalent radius of the carbon atoms constituting diamond is 0.077 nm
• the covalent radius of phosphorus is 0.106 nm
• the covalent radius of Y ⁇ is 0.102 nm. Since the covalent radius of phosphorus or y ⁇ is considerably larger than the covalent radius of carbon, when vapor-phase synthesis is performed while doping with phosphorus or y ⁇ , it grows when the diamond thickness grows to about 10 im or more. There was also a problem that cracked diamonds were cracked.
• nitrogen is another dopant experimentally confirmed to have n-type semiconductor characteristics, but the activation energy of nitrogen-doped diamond is about 1.7 eV, Severity is more than 10 1 Q Q ⁇ cm and insulator. Furthermore, it is known that when lithium is added, it exhibits n-type half-body characteristics.
• JP-A-3-205398, JP-A-4-175295, and JP-A-11-154443 disclose that water or a liquid organic compound containing lithium or a lithium compound is used as a raw material or lithium or lithium. The compound is vaporized and introduced into the synthesis furnace, which is doped with lithium during the vapor phase growth of the diamond by hot filament CVD or various plasma CVD methods to produce low-resistance n-type semiconductor diamond. Have been disclosed.
• Japanese Patent Application Laid-Open No. 7-106266 discloses a method of introducing lithium between lattices to obtain a low-resistance n-type semiconductor diamond.
• This method uses a nitrogen compound of lithium as a raw material and does lithium doping of diamond by ECR plasma without destroying the crystallinity of the diamond.
• the ionic radius of lithium (0.060 nm) and the ionic radius of nitrogen (0.027 nm) are both smaller than the covalent radius of carbon (0.077 nm).
• both lithium and nitrogen can enter the lattice without destroying the diamond crystal structure.
• lithium and nitrogen are heavily doped between diamond lattices, but it is not easy to control the concentration of lithium and nitrogen mixed.
• an object of the present invention is to solve a problem that occurs when doping with lithium, and to provide a low-resistance n-type semiconductor diamond having good crystallinity and a method for producing the same.
• a lithium atom and a nitrogen atom is contained both 1 0 1 7 cm- 3 or more.
• the lithium atom concentration C L i and the nitrogen atom concentration C N are 0.1 ⁇ C L iZ It is preferably l0.0.
• the low n-type semiconductor diamond is a single crystal diamond. Then, the lithium atom is doped at the interstitial position of the carbon atom constituting diamond, the nitrogen atom is doped at the carbon atom and the substitution position, and the lithium atom and the nitrogen atom are adjacent to each other.
• a lithium atom and a nitrogen source it is preferable that the center distance of the element is not less than 0.145 11111 and not more than 0.155 nm, and the activation energy of the low-resistance n-type semiconductor diamond of the present invention is not less than 0.056. 0. or less 2 e V, the resistivity of Ru der below 1 0 3 ⁇ ⁇ cm.
• the low-resistance n-type semiconductor diamond of the present invention is a method for producing on a substrate by a vapor phase synthesis method, and is characterized in that a raw material is photodecomposed by a photoexcitation method using vacuum ultraviolet light. It is preferable to irradiate an excimer laser beam to the lithium oxide provided in the champer to scatter lithium atoms to reach the vicinity of the substrate. Further, it is preferable that the nitrogen and carbon raw materials are gas, and the supply amount is 0.001 ⁇ nitrogen amount / carbon amount ⁇ 0.1, and the nitrogen raw material is nitrogen gas or ammonia.
• the wavelength of the vacuum ultraviolet light is preferably 65 nm or more and 75 nm or less.
• the pressure at the time of the vapor phase synthesis be 1330 Pa or more and 20000 Pa or less, and the substrate temperature be 100 ° C. or more and 1000 ° C. or less.
• the figure shows an example of a diamond synthesis device used in the present invention.
• the inventor has determined that nitrogen (covalent bond) having a covalent bond radius smaller than the covalent bond radius (0.077 nm) of the carbon constituting diamond is required. radius: 0. 074nm) and lithium (ion radius: I began to see that it is sufficient to 0. 06 Onm) and at the same time both 1 0 17 c m_ 3 or more de one up the.
• the ratio (C LI / C N ) of the lithium atom concentration C and the nitrogen atom concentration C N in the low-resistance n-type semiconductor diamond is preferably 0.1 or more and 10.0 or less.
• any of Lithium and 'nitrogen is less than 10 17 cm_ 3, it can not be achieved to have lower resistance.
• the ratio of lithium atom concentration to nitrogen atom concentration ( CL If is less than 0.1, the temperature dependence of the resistivity increases as in the case of single doping of nitrogen.
• the value exceeds 10.0 lithium moves around the diamond, and stable electric characteristics Can not be obtained.
• the doped lithium moves around the diamond lattice as described above, but if nitrogen is doped simultaneously with lithium into the substitution position of carbon atoms constituting diamond, the interstitial lattice is reduced.
• the distance between the center of the lithium atom and the center of the nitrogen atom is preferably 0.145 nm or more and 0.155 nm or less. If it is less than 0.14511111 ⁇ 0.15 nm, it will be difficult to simultaneously drop lithium and nitrogen.
• a method of photoexcitation using vacuum ultraviolet light is effective.
• a carbon-containing material such as methane to be introduced and hydrogen are introduced under appropriate temperature and pressure conditions.
• vacuum ultraviolet light to selectively generate CH 3 radicals and H radicals by light ⁇ , which causes crystal defects in the diamond to be formed in the vapor phase synthesis of diamond. Almost no CH 2 or CH radicals are generated.
• a high-quality diamond thin film having few crystal defects in the generated diamond film and little contamination with impurities having different crystallinities can be obtained.
• a light source of the vacuum ultraviolet light synchrotron radiation, undulee, or ultra-high temperature plasma such as laser plasma can be used.
• lithium and nitrogen raw materials it is necessary to supply lithium and nitrogen raw materials to obtain diamonds doped with lithium and nitrogen.
• a method for supplying lithium in order to prevent generation of CH 2 radicals and CH radicals other than CH 3 radicals that impair the crystallinity of the diamond, lithium oxide is irradiated with an excimer laser to emit lithium atoms. It was found that the object could be achieved by scattering the gas to reach the vicinity of the substrate and using nitrogen gas or ammonia gas as the nitrogen source.
• the method for supplying lithium does not require equipment such as heating and vaporization for introducing a conventional lithium-containing raw material into a semiconductor diamond synthesis apparatus, and is very safe.
• the amount of nitrogen is less than 0.001 of the amount of carbon, the amount of nitrogen contained in the diamond to be formed will be small, and it will be difficult to obtain the low-resistance n-type semiconductor diamond of the present invention. On the other hand, if the nitrogen content is more than 0.1 of the carbon content, the quality (crystal ft) of the formed diamond is deteriorated.
• the pressure at the time of the vapor phase synthesis is preferably from 1330 Pa to 20000 Pa. If it is less than 133 Pa, diamond cannot be formed, and if it exceeds 2000 Pa, the quality (crystallinity) of the diamond deteriorates. If the substrate temperature is lower than 100 ° C, diamond cannot be formed. If the substrate temperature exceeds 100 ° C, the quality (crystal 3 ⁇ 4) of the diamond deteriorates. 0 nC or less is preferable.
• diamond with good crystallinity means that the impurities that are desired to be mixed into the substitution position are mixed into the substitution position, and the impurities that are desired to be mixed between the lattices are mixed between the lattices.
• lithium has a small ion radius of 0.060 nm, which is smaller than the covalent bond radius of carbon of 0.077 nm, lithium is simultaneously doped during vapor-phase synthesis of diamond by photoexcitation using vacuum ultraviolet light. In this case, lithium atoms do not enter the substitution position but enter the interstitial position.
• the covalent radius of nitrogen is 0.074 nm, which is close to the covalent radius of carbon, and if one valence electron is emitted, it becomes a sp 3 bond, so that it is mixed into the substitution site.
• the formation energy was calculated by a simulation based on the first principle calculation when lithium interstitial doping and nitrogen substitution doping were combined. Also, when the lithium atom and the nitrogen atom are adjacent to each other for, the formation energy was calculated by simulation based on the first principles calculation.
• the formation energy is lower when the lithium atoms present at the interstitial positions and the nitrogen atoms present at the substitution positions are close to each other than when they are separated from each other. It turned out to be stable.
• the activation energy in this case was calculated to be 0.10 eV.
• the distance between the lithium atom and the nitrogen atom in the optimum structure was 0.1494 ⁇ . .
• the distance between the lithium atom and the nitrogen atom is less than 0.145 nm, the formation energy is too high, so that the lithium atom and the nitrogen atom are difficult to be simultaneously doped into the diamond.
• the activation energy becomes larger than 0.10 eV when the length is longer than 0.155 nm, and that the dependence of the TO: ratio becomes large.
• lithium atoms and nitrogen atoms are simultaneously doped, and if the center distance between lithium atoms and nitrogen atoms is 0.145 nm or more and 0.155 nm or less, low g We found that it is a ⁇ n type semiconductor. This diamond could be expected to have lower activation energy.
• n-type semiconductor diamond in which lithium and nitrogen are simultaneously doped can be formed.
• FIG. 1 is a schematic view showing an example of a diamond gas-phase synthesis apparatus used for carrying out the present invention.
• the diamond substrate 2 is set on the substrate holder 3 in the vacuum chamber 11.
• the temperature of the diamond substrate 2 can be adjusted from room temperature to a few hundred degrees by a heating heater.
• the vacuum chamber 1 is divided by the differential pressure walls 5 and 6 into a portion including the diamond substrate 2, a portion including the target 7 made of lithium oxide, and a portion to which the light source 8 is connected. Slits 9 and 10 are provided in each differential pressure wall, and each of the portions is provided with separate vacuum exhaust ports 11, 12 and 13 for performing differential pressure exhaust.
• the portion including the diamond substrate 2 is provided with gas introduction pipes 14, 15, and 16 for taking in the source gases hydrogen, methane, and ammonia. Source gas is supplied to mass flow controllers 20, 21, connected to gas cylinders 17, 18, 19. Each of them can be adjusted to a predetermined flow rate by means of 22.
• the portion including the target 7 is provided with an optical window 23 for excimer laser made of:
• the inside of the vacuum chamber 1 is evacuated to vacuum through the vacuum exhaust ports 11, 12 and 13.
• the material gas is supplied to the portion including the diamond substrate 2 via the gas introduction pipes 14, 15, 16 so as to adjust the flow rate so as to have a predetermined mixing ratio, and to supply the gas to a predetermined pressure.
• the excimer laser beam 24 irradiates the target 7 through the optical window 23.
• lithium atoms are scattered from the target 7 made of lithium oxide, and reach the vicinity of the diamond substrate 2 through the slit 9 provided in the differential pressure wall 5.
• the diamond substrate 2 heated by the heater 3 is irradiated with light passing through the slit 10 provided in the differential pressure wall 6 from the light source 8 to photoly decompose the supplied source gas and to emit the target gas.
• the chemical reaction on the diamond substrate 2 is promoted in combination with the more flying lithium atoms.
• diamond doped with lithium and nitrogen is homoepitaxially grown on the diamond single crystal substrate 2 to form a low-resistance n-type semiconductor diamond.
• the high-temperature high-pressure synthesized II a diamond single crystal substrate placed were Champa one vacuum pump, evacuated to 133 X10- 9 Pa (10_ 9 torr ), was synthesized Daiyamondo under the conditions below.
• Diode substrate temperature 300 ° C
• the substitution state was measured by electron spin resonance (ESR).
• the nitrogen in the artificially synthesized diamond is an isolated substitution type, and if the nitrogen in the diamond formed according to the present invention is also an isolated substitution ⁇ , a signal unique to the isolated substitution type nitrogen should be detected by ESR measurement. is there. As a result of the measurement, it was found that the isolated substitutional nitrogen was less than 10% of the total nitrogen. From this result, it is concluded that lithium atoms exist near most of the nitrogen atoms.
• the temperature of the diamond single crystal was raised to 873 K, but the characteristics were very stable. This indicates that the interstitial lithium atom is fixed by the nitrogen atom present at the substitution position.
• the activation energy value of 0.1 leV in this electrical property measurement is a theoretical activation energy value of 0.1494 nm when the center distance between lithium and nitrogen atoms is 0.1494 nm in the first principle calculation. It was confirmed that the distance between lithium atoms and nitrogen atoms in the formed diamond single crystal was about 0.15 nm, which was close to .10 eV.
• a low-resistance n-type semiconductor diamond which has never existed before, can be obtained by simultaneously doping lithium atoms and nitrogen atoms into diamond.
• power devices that can withstand high-frequency and high-output operations at high temperatures, light-emitting devices that can emit ultraviolet light, and electron-emitting devices that can be driven at low temperatures can do.

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• 2002
  • 2002-12-27 JP JP2002379229A patent/JP2004214264A/ja active Pending
• 2003
  • 2003-12-22 WO PCT/JP2003/016492 patent/WO2004061167A1/ja not_active Ceased
  • 2003-12-22 US US10/506,493 patent/US7255744B2/en not_active Expired - Fee Related
  • 2003-12-22 CN CNB2003801002131A patent/CN100337310C/zh not_active Expired - Fee Related
  • 2003-12-22 EP EP03781010A patent/EP1577425A4/en not_active Withdrawn
  • 2003-12-22 KR KR1020047013528A patent/KR20050084776A/ko not_active Withdrawn
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