JP2006287028A - Laser luminescence structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser luminescence structure capable of enhancing the energy conversion effect by a special structure. <P>SOLUTION: The single crystal of the element of II-VI is formed on the surface of a plane anode surface as a laser luminescent body. A cathode 1 with a nanocarbon graphite, formed on the surface thereof to excite the luminescence body, is employed to hit electronic beams 3 from the cathode against the single crystal formed on the surface of an anode 2, and to generate laser luminescence 15, as a result of the electroluminescent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser emitting structure that can be used for illumination of a display and generation of a light beam, and an optical radiation source device using the same.

  Various laser crystals are made for vision in each field of human activity. In the overwhelming case, the principle of operation of the light source means to convert current into light. Depending on the spatial application, the light source must meet exact requirements regarding radiation intensity and directionality, its spectral distribution, overall dimensions and other characteristics.

  Laser development using semiconductors has been underway since the 1950s. A semiconductor laser generally has a double heterostructure. This complicates the laser emission structure. In addition, an intrinsic semiconductor and two or more types of semiconductor materials, p-type and n-type, are always required in light emission principle.

  In contrast, electroluminescence, which is performed by applying an electron beam to a light emitter, differs from heat, photons and other types of excited luminescence, and emits light without any energy absorption in the cathode (emitter) material. Provide high efficiency light source.

  Further, the simple structure can basically reduce the structural cost, and in the case of electroluminescence, a large power can be obtained and bright illumination can be easily obtained.

However, in order to provide an electron beam with a practically high current density using an electro-luminescent cathode, a very high electric field strength (10 ⁸ to 10 ⁹ V / m) effective on the cathode surface is required. Must be applied.
In order to obtain a high-intensity electron beam by obtaining a high electric field strength, the cathode is pointed, but usually the light emission from a cathode with a size of about submicron is very unstable. Field-effect light emission fundamentally hinders the use of tip- and edge-type electroluminescent cathodes in wide-purpose devices and equipment.

Currently known light sources are cathodoluminescent light sources (eg, WO 97/07531) where a small filament of conductive material is used as the electroluminescent cathode. In this type of lamp, the cathode is confined within a vacuum glass bulb with a transparent conductive coating on its inner surface that serves as the anode. A light emitting layer that emits light by electron beam excitation is formed on the conductive coating. However, one of the disadvantages with such a configuration is to provide a sufficiently high electric field strength required for electroluminescence and to provide a voltage value between the anode and cathode to serve practical purposes. , Very small diameter (1 μm to 15 μm) filaments must be used.
WO00 / 40508 WO97 / 07531 JP 2002-358873 A JP 2001-319560 A JP-A-2005-44616

  A basic problem of the present invention is that a laser emitting structure that emits laser light by a resonant mirror by irradiating a light emitter with an electron beam stably obtained by field emission from a cathode prepared using nanocarbon graphite or carbon nanotubes or It is to provide a luminous lamp.

  The second object of the present invention is a relatively simple structure that does not require a heterostructure, such as a semiconductor laser, has a simple structure, and has only to be n-type, p-type, or intrinsic. It is to provide a laser light emitting structure that can be manufactured by the following method.

  Furthermore, a third problem is to provide a high-luminance and high-power laser light-emitting structure that can be manufactured with a simple structure that does not require a quantum well structure like a semiconductor laser.

  A fourth object of the present invention is to provide a laser light emitting structure in which the emission color can be easily controlled by changing the kind and amount of single crystal and polycrystal doping.

  In order to solve the above problems, as a result of earnest research, the light emitting anode is flat, can be used as a surface light source, and can be stably obtained by field emission from a cathode made using nanocarbon graphite or carbon nanotube. We have invented a laser light emitting structure that irradiates a light emitting anode with an electron beam and emits laser light with a resonant mirror. It has been found that it can be used as a light source that can increase brightness and power. The configuration of each item below.

  (1) As a laser emitter, an amorphous, polycrystalline, or single crystal emitter made of a semiconductor or oxide material is formed on a planar anode surface, and a cathode having nanocarbon graphite formed on the surface is used to excite the emitter. Thus, a laser light emitting structure having a structure in which an electron beam from the cathode is applied to the amorphous, polycrystalline, or single crystal light emitter formed on the planar anode surface to cause laser light emission as a result of electroluminescence.

(2) The cathode is in the form of a long planar body, a linear or mesh planar body, or a cylindrical body. Nanocarbon graphite or carbon nanotubes are formed on the surface of the cathode, and the light emitter is placed at a position relative to the nanocarbon graphite. An anode with a layer provided on the anode surface is arranged.
(3) The cathode is a long planar body, and a nanocarbon graphite or carbon nanotube layer is formed on the surface, and the mirror reflection layer 5 and the planar anode 6 are arranged in this order in parallel. The planar anode as a whole has a planar body or a cylindrical shape. In the case of a cylindrical shape, a transparent substrate 8 and a mirror surface 14 are provided on the bottom and top planes, and laser is emitted from the plane.

(4) The space between the planar anode and the planar cathode is maintained at a degree of vacuum that allows laser emission.
(5) A condenser lens is provided at the front position of the planar light emitting anode to hold the emitted light beam in parallel.

  As shown in FIG. 1, the basic structure of the present invention comprises two devices, an electron gun unit and a light emitting unit. The electron gun section is composed of a cathode 1 on which nanosize carbon is deposited and an anode 2 made of metal such as ITO or aluminum. The light emitting portion of the amorphous, polycrystalline, or single crystal light emitter is configured by sandwiching the light emitter 5 between the two dielectrics 4 and 6.

The carbon material used for the laser light emitting structure of the present invention is generally a known technique, and it is known that electroluminescence is generated at a very low electric field strength (10 ⁶ to 10 ⁷ V / m). It has been. This is because the structural element is of a nanometer size, and is due to the electronic properties inherent to nanostructured carbon (see Patent Document 1). When such a material is used as the electron emitter (cathode), the voltage value applied between the anode and the cathode for producing an electron beam can be basically reduced.

That is, as such a carbon material used in the laser light emitting structure of the present invention, nanocarbon graphite or carbon nanotube is formed on the cathode surface and used as claimed.
That is, [nanocarbon graphite] is a carbon graphite crystal having a size of about submicron and a small width of particle distribution.
FIG. 4 is a photomicrograph of a thin film in which nanocarbon graphite used in the apparatus of the present invention is deposited on silicon. It was deposited at an acceleration voltage of 25.0 kV, and the full scale width of the scale in the photograph was 50 micrometers, which is a 1000 × micrograph. FIG. 5 is an elemental analysis chart of the nanocarbon graphite deposited thin film, in which carbon and silicon lines appear. FIG. 6 shows a thin film X-ray diffraction chart of the nanocarbon graphite deposited thin film. ● indicates a silicon diffraction line, and ○ indicates a carbon diffraction line.

[Carbon nano tube] means tube-like carbon having a diameter of about submicron.
A metal catalyst is used for the production of [carbon nanotube], and the [carbon nanotube] produced by this method contains a metal catalyst. When this [carbon nanotube] is used as an electron emitter, metal catalyst particles are segregated on the surface of the nanotube, and the electron emission efficiency is lowered. In order to obtain the electron emission efficiency necessary for light emission, the metal fine particles must be removed by chemical treatment.

  Another disadvantage inherent in such illuminants is that when the illuminant is irradiated with an electron beam, a portion of the illuminant evaporates and onto the inner surface of the cylindrical glass bulb. It is that the luminous body precipitates. Some of the light emitted by the layer is absorbed when the light passes through the transparent lamp surface, thereby adversely affecting the total conversion efficiency of electrical energy into light.

In the present invention, single crystal samples such as II-VI group, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, III-V group, oxides, etc. as layered oxy Sulfide (LaO) CuS or amorphous Al ₂ O ₃ is used and disposed at a position sandwiched between two dielectric mirrors as shown in the cross-sectional view of FIG. All of these are enclosed in a vacuum vessel. Instead of II-VI and III-V light emitters, a quantum transfer substrate can also be used.
In a further preferred embodiment of the invention, the light source is provided on a base enclosed in a transparent envelope that is evacuated.

  The laser light emitting device according to the present invention has a cross-sectional structure shown in principle as shown in FIG. The cathode 1 coupled to the negative electrode is placed at a position parallel to the anode 2 of ITO coupled to the positive electrode with a film thickness of 1 μm or less, and an electron beam 3 is obtained by applying a voltage. Here, a carbon-based nanocarbon material thin film layer that can generate an electron beam with high efficiency by the electric field applied between the electrodes is formed on the cathode surface. As this material, nanometer-sized graphite crystals are extremely suitable. On the back surface of the ITO, a metal having a good light reflectivity with a film thickness of 1 μm or less or a dielectric layer 4 having a reflectivity of 90% or more is formed, and a light emitter 5 is disposed at a position facing this. A transparent substrate 7 is disposed on the dielectric 6 for structural support. A dielectric mirror 6 having a reflectivity of 90% or more for reflecting the light obtained by electron beam irradiation and aligning the phases is placed at a position facing the light emitter. The light whose phases are aligned by the two mirrors is emitted as laser light 15 when the intensity exceeds a certain value, and is converted into parallel light or condensed laser by the lens 10.

Generally, in the laser light emitting structure of the present invention, the planar anode is a long planar body and emits light from the entire plane.
For example, the following parameter conditions are used.
Luminescent material: ZnS, degree of vacuum = 10 ⁻⁶ Torr
At this time, the intensity of light emitted from the light emitting structure changes as follows depending on the applied voltage.
Applied voltage = 4 kV, emission intensity = 20,000 cd / m ²
Applied voltage = 5 kV, emission intensity = 30,000 cd / m ²
Applied voltage = 10 kV, emission intensity = 100,000 cd / m ²

As shown in FIG. 2, the cathode is electrically coupled to the negative electrode outside the vacuum vessel so that a negative potential can be applied. That is, a potential is applied between the anode 3 and the cathode 2 so as to obtain a predetermined operating voltage value, and the electric field intensity level effective on the cathode necessary for obtaining an electroluminescent current of a necessary magnitude. become.
For example, a required electric field strength of a value of 1.25 × 10 ⁶ V / m or more is caused by a cathode having a rectangular area s having a length l and a width w.
According to the anode area Smm ² in (I) F = V / [ d ln (S / s)], achieved at 4kV or higher voltage (V).
Therefore, when a voltage of 4 kV or more is applied, the speed of electrons emitted from the cathode is accelerated in the space between the electrodes, and electron-excited emission by anode surface emission becomes possible.

  In the apparatus of the present invention, an extraction electrode capable of controlling the intensity of the electron beam can be used. By appropriately selecting the voltage applied to this electrode, the state of space charge is adjusted and the electron beam intensity is controlled. All these electrodes are fixed in place inside the lamp, evacuated to the required level and hermetically sealed. A getter can be used to keep the interior of the lamp at the required vacuum level for a long time.

  One example of cathodic light emission according to the present invention is shown as a light emitter having a structure as shown in FIG. In such a case, the lamp can be provided with a surface from which the laser beam 15 is emitted on the front surface, and the luminous flux can be controlled from the light emitter.

The cathode surface 1 is coated with a nanocarbon graphite vapor deposition layer. The anode has a planar shape, and its surface is coated with ITO or aluminum. Then, the light emitter layer 5 is provided through the dielectric mirror surface layer 4, and the mirror body 6 is provided. Due to the effect of the electron beam emitted from the cathode, the light emitter 5 emits light and is resonated between the mirror bodies 4 and 6 to cause laser emission.
The cathode and the anode, which are mechanically fixed at a predetermined interval, are electrically coupled to each other.

  FIG. 1 includes an anode 2 and a cathode 1, the anode and the cathode are separated from each other, an electron beam 3 generated on the cathode surface 1 (nanocarbon graphite layer surface) is applied to the surface of the anode 2, and a phosphor layer in the anode 5 schematically shows a flat lamp device in which the light emitted in 5 is amplified and modulated between dielectric mirror bodies 4 and 7, emitted in the form of a razor beam 15, and emitted by a light beam 15. FIG. This device is placed in a jacket (not shown) placed in a vacuum with a security seal.

  FIG. 2 is a cross-sectional view showing a specific example of a planar laser emission structure manufactured according to the present invention. In this case, the cathode 1 is a planar electrode body, and a nanocarbon graphite thin layer (about 2 μm thick) is formed on the surface thereof by vapor deposition. The phosphor layer 5 is sandwiched between dielectric mirrors 4 and 6 having a reflectance of 90% or more, and these are disposed between the cathode 1 and the anode 2. The entire apparatus is held in a transparent outer casing 11 and is vacuum-sealed.

  The cathode 1 emits an electron beam 15 from the planar deposited nanocarbon graphite layer 3. The electron beam 3 penetrates from the mirror body layer of the anode 2, hits the light emitter layer 6, and emits a light beam. In this case, the distance between the cathode and the light emitter of the anode is 0.1 to 30.0 mm, the size of the cathode is, for example, 25 × 25 mm, and the degree of vacuum is lower than 1 atm in the outer casing. . The thickness of the nanocarbon graphite thin layer is about 2 μm, and the thickness of the phosphor layer is 0.1 to 1 mm.

  FIG. 3 shows an electron beam 3 obtained by applying a voltage to the cathode 1 and the cylindrical anode 2 to irradiate an inner light emitter layer 5 to emit an electron beam. Sectional drawing which shows the specific example of the laser crystal light emission structure which raise | generates resonance between the mirror surface bodies 4,6,8,9 comprised with a dielectric material or an insulator, and a laser crystal light emission emits from the right mirror surface body 9 It is. That is, the reflectance of the mirror body 8 is 100%, and the reflectance of the mirror body 9 is 95%.

The distance between the cathode and the light emitter is 0.1 to 10 mm, the voltage applied between them is 1 to 50 kV, and the current is 0.1 to 30 mA / cm ² . In this structure, the density of the electron beam is very high due to the nanocarbon graphite layer deposited on the inner surface of the cathode 2, and the effect is particularly remarkable in the laser light emitting structure having the structure as shown in the figure. . Electrons penetrate into the light emitter of about 3 μm and emit light by the energy. The light emitter 5 has a single crystal, polycrystal, or amorphous structure using elements II-VI and III-V, and has either an n structure or a p structure. It depends on the type of illuminant.

  The cathode-emitting laser emission structure proposed in the present invention is a novel type of light-emitting device (lamp). The construction of the lamp made according to the present invention achieves a higher conversion efficiency to light of electrical energy compared to other known types of light sources. Certain types of lamps find application areas for various purposes that may be used in place of the known light sources described above. Certain types of lamps have basic advantages over known light sources when high brightness and minimal heat radiation are required.

  Considered lamp construction and manufacturing techniques use materials that are non-toxic or ecologically harmless. With a suitably selected phosphor, a given type of lamp can generate light with a predetermined spectral characteristic with high energy efficiency. In the lamp of the proposed configuration, a liquid crystal display and low power consumption and sufficient luminous intensity indicator applications are found. Finally, the lamp of the present invention having an electrically insulated anode is easy to control the color and easy to control the output, so that the headlamp of a medical device, machine tool, projector, automobile, etc. It serves as a laser display, indicator, and similar devices for providing visual information.

It is a schematic diagram which shows the principle of the laser light emission structure by this invention. The specific example of the laser light emission structure by this invention is shown. It is a schematic cross section which shows the structure of the other specific example of the laser light emission structure by this invention. It is a microscope picture of the nano carbon graphite thin film used for the laser light emission structure by this invention. It is a chart of the elemental analysis of the nano carbon graphite thin film used for the present invention. 1 shows a thin film X-ray diffraction chart of a nanocarbon graphite thin film used in the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cathode, 2 ... Anode, 3 ... Electron beam, 4, 6, 7, 9 ... Dielectric mirror surface body, 5 ... Light-emitting body layer, 11 ... Cover body, 15 ... Laser beam

Claims (5)

  An amorphous, polycrystalline, or single crystal of a semiconductor material or oxide material is used as a laser emitter, and the emitter is formed on a planar anode surface, and nanocarbon graphite or carbon nanotube is used to excite the emitter. A laser light emitting structure characterized by having a structure in which an electron beam obtained by field effect emission is irradiated from a cathode produced using the cathode to the light emitter, and the resulting light emission is emitted by a resonance mirror.   The cathode is a long planar body, a linear, mesh-shaped planar body, or a cylindrical shape. Nanocarbon graphite or carbon nanotubes are formed on the surface of the cathode, and the phosphor layer is placed at a position corresponding thereto. 2. The laser light emitting structure according to claim 1, wherein an anode provided on the surface is arranged.   The cathode is a long planar body, a nanocarbon graphite or carbon nanotube layer is formed on the surface thereof, and the specular reflection layer 5 and the planar anode 6 are arranged in this order in parallel to the planar anode. 2 is a flat body or a cylindrical shape as a whole, and in the case of a cylindrical shape, a transparent base 8 and a mirror surface 14 are provided on a bottom surface and a top surface, and a laser is emitted from the flat surface. Laser light emitting structure.   The laser light emitting structure according to any one of claims 1 to 3, wherein the anode and the cathode are maintained at a degree of vacuum capable of laser light emission.   The laser light emitting structure according to any one of claims 1 to 4, wherein a condensing lens is provided at a front position of the light emitting anode to hold the emitted light beam in parallel.