JP2002084037A - Light emitting body and structure, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emission body made of zinc oxide having high-level light emitting capacity by providing a cyclic structure of nanometer to submicron size. SOLUTION: This light emission body has a base 2 and zinc oxide columns 1 consisting principally of zinc oxide, and the zinc oxide columns 1 are substantially hexagonal and arranged substantially at right angles to the surface of the base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting body, a structure, and a method of manufacturing the same, and more particularly, to a structure having a periodic structure of nanometer to submicron size, particularly a light-emitting body in which columnar substances made of zinc oxide are periodically arranged. , A light emitting element, a laser, and an optical element having the above structure.

[0002]

2. Description of the Related Art Conventionally, zinc oxide has characteristics such as a laser or LED, a phosphor, a waveguide, a transparent electrode, a piezoelectric element, a photoelectric conversion element, a photosensitive material, etc. because of its characteristics such as a wide gap semiconductor and piezoelectric characteristics. Research has been actively conducted in fields such as decomposition of harmful substances and antibacterial activity. For example, in Japanese Patent Application Laid-Open No. Hei 10-256673, it was shown that laser oscillation in the ultraviolet region is possible from a thin film of zinc oxide.

On the other hand, by reducing the size of a semiconductor from nanometers to submicron sizes, unique electrical, optical, and chemical properties can be expected in terms of electron confinement and surface action. From this point of view, if zinc oxide can be used to realize a nanometer-sized structure with excellent crystallinity, electrical, optical and chemical properties including light-emitting elements and photoelectric conversion functions can be realized. Can be expected to further improve the mechanical properties.

[0004]

However, conventionally,
It has been difficult to prepare a zinc oxide material having a nano size and excellent crystallinity by a simple method. In general, as a method for producing a nano-sized material, there is a method using a semiconductor processing technique including a fine pattern drawing technique such as photolithography, electron beam exposure, and X-ray diffraction exposure. However, these methods have problems such as low yield and high device cost, and a method that can be created with a simple method with good reproducibility is desired.

[0005] As a technique for preparing nano-sized fine particles, there is a technique of applying and firing a colloid solution. This method is relatively simple, but has problems in controllability and reproducibility with respect to the crystallinity and the shape of fine particles of the zinc oxide to be produced.

An example of controlling the structure of zinc oxide having a nanometer-sized structure is disclosed in the above-mentioned JP-A-10-25.
No. 6673 discloses that a laser oscillation threshold value is low when a hexagonal prism nanocrystal thin film having a size of about 50 nm is used.

As another example of producing zinc oxide having a columnar shape, there is a report that zinc oxide whiskers are grown on a substrate by open-air CVD (see Jpn.
J. Appl. Phys. "Vol. 38 (1999)
L586). However, the diameter of the whisker is relatively large, that is, several microns or more.

[0008] These methods have not been applied sufficiently because the substrate is limited to a sapphire substrate, high-temperature growth conditions are used, and the control of the structure is insufficient.

In view of the above, an object of the present invention is to provide a structure made of zinc oxide having a periodic structure of nanometer to submicron size on a conductive film. This is to be applied to optical elements such as elements. Another object of the present invention is to provide a method for easily manufacturing the above-mentioned luminous body.

[0010]

The above objects can be attained by the following constitution and manufacturing method of the present invention. That is, the present invention has a substrate and a plurality of columnar members containing zinc oxide as a main component, and the columnar members are substantially hexagonal prism-shaped,
A luminous body characterized by being arranged substantially perpendicular to the surface of the base.

It is preferable that a hexagonal column-shaped zinc oxide column periodically arranged substantially vertically on the substrate is provided. It is preferable that the arrangement period of the periodically arranged zinc oxide columns is smaller than the emission wavelength. The zinc oxide columns are preferably arranged in a triangular lattice. It is preferable that the zinc oxide column has a regular hexagonal cross section, and the arrangement orientation of the periodic structure is substantially equal to the direction from the column center to the vertex direction of the hexagonal columnar zinc oxide column. It is preferable that the zinc oxide column has a regular hexagonal cross section, and that the arrangement orientation of the periodic structure is substantially equal to the direction from the column center of the hexagonal column-shaped zinc oxide column to the center of the side surface. Preferably, the base comprises a substrate and a conductive film on the substrate.

Preferably, the conductive film contains Pt, Cu or Pd as a main component. The conductive film is preferably oriented in the 111 direction perpendicular to the substrate. The zinc oxide columns are preferably oriented in the c-axis direction perpendicular to the substrate. The zinc oxide columns are preferably arranged in the pores of anodized alumina.

Further, the present invention is a structure characterized by having a base and a hexagonal column-shaped zinc oxide column which is arranged vertically upright on the base. Preferably, the base comprises a substrate and a conductive film on the substrate.

Further, the present invention provides a step of forming a conductive film on a substrate to form a substrate, and a step of forming a pattern of periodically arranged circular or elliptical pores on the substrate. And a step of growing a zinc oxide column in a solution containing zinc ions in pores on the substrate.

The pores are preferably elliptical. The step of forming the pattern of circular or elliptical pores includes the step of forming a pore formation starting point on the surface of aluminum provided on the substrate, and the step of forming an anode having pores by anodizing the aluminum. It is preferable to have a step of forming alumina oxide.

According to the present invention, a zinc oxide material having a nano-sized size and excellent in crystallinity, in particular, a nano-sized zinc oxide pillar can be produced. Thereby, a high-performance luminous body can be obtained. In particular, a very fine zinc oxide pillar having a diameter of about several tens to 500 nm, that is, a very fine zinc oxide pillar can be formed upright on a conductive substrate. This enables electrical connection between the zinc oxide pillar and the base electrode. This allows
There is no need to use expensive single crystal substrates such as sapphire.

Further, by periodically arranging the zinc oxide columns in a submicron size, it is possible to apply the present invention to a photonic crystal as an optical element. In particular, also in JP-A-10-256672, the zinc oxide columns are hexagonal columns but are continuous films, and the present invention is different in that the columnar zinc oxides are spaced apart from each other and are periodically arranged.

The photonic crystal is a crystal in which two or more types of portions having different refractive indexes (dielectric constants) are periodically arranged to control the optical properties thereof (JD Joan).
nopooulous et al. "Photoni
c Crystals "Princeton Univ
efficiency press). Such a medium has a refractive index of about a wavelength even in light, such that the dispersion relation between energy E and wave number k is analogized to form a band in a semiconductor band formation theory by Bragg reflection of an electron wave. Periodicity creates a photonic band. Further, depending on the periodic structure, a wavelength region where light cannot exist, that is, a photonic band gap is formed. In order to control such a photonic band, the size of the structural period needs to be a size of about the wavelength of light to a fraction of the wavelength of light.

That is, in the present invention, a periodic structure (photonic crystal) having a size equal to or smaller than the wavelength of light is prepared from zinc oxide, and the periodic structure is appropriately designed with respect to the emission spectrum and dispersion characteristics of zinc oxide. It can be expected to be applied to various optical elements including light emitting elements. In particular, by using a mode in which the group velocity of the photonic band is small or a localized mode associated with a defect structure, it is possible to increase the efficiency of the light-emitting element, lower the oscillation threshold of the laser element, and the like. In addition, when used as a phosphor, it can be used for controlling the fluorescence lifetime. That is, by using columnar zinc oxide as a periodic arrangement and using it as a photonic crystal, it is possible to increase the efficiency of a light-emitting element, lower the oscillation threshold of a laser element, and the like. In addition, photonic crystals can be expected to be applied as various optical elements such as waveguides and polarizing elements.

In particular, zinc oxide can be used as a light emitting material that emits band-edge light of ultraviolet light or green light due to oxygen deficiency or interstitial Zn defect, and has a periodic structure (photonic crystal) corresponding to the light emission wavelength. By applying the light-emitting element, a high-performance light-emitting element can be provided in a desired wavelength region.

The structure provided with the zinc oxide column of the present invention comprises:
In addition to light-emitting devices, they can be applied in a wide range as functional materials such as photoelectric conversion devices, photocatalysts, field emission electron-emitting devices, various electronic devices and microdevices, and structural materials.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a structure (light emitting body) in which a zinc oxide column is disposed on a substrate of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

<Structure> FIG. 1 is a conceptual view showing an example of the structure (light emitting body) of the present invention. As shown in FIG. 1, the luminous body of the present invention has a zinc oxide column 1 which is a luminescent material and is periodically arranged upright on a base 2. Zinc oxide pillar 1 of the present invention
Has oxygen and zinc as main components, and has a hexagonal columnar structure in particular.

FIG. 2 is a conceptual diagram showing an example of the shape of the zinc oxide pillar of the present invention viewed from above. When the hexagonal prism is viewed from above, the hexagonal prism starts with a regular hexagon as shown in FIG.
Hexagons as shown in (b) and (c) and hexagons with rounded corners as shown in FIG.

FIG. 3 is a perspective view showing a zinc oxide column of the present invention. A regular hexagonal prism as shown in FIG. 3A, FIG. 3B
As shown in FIG. 3 (c), a hexagonal prism having a rounded corner as shown in FIG.

The zinc oxide column of the present invention may be polycrystalline, single crystal,
Although it can have an arbitrary crystal structure such as amorphous, a structure having excellent luminous ability is preferable, and a structure having excellent crystallinity, particularly a single crystal, is preferable. By appropriately selecting the zinc oxide film forming conditions and the underlying substrate described later, the c-axis can be directed upward with respect to the substrate, and zinc oxide having excellent orientation can be grown. In particular, hexagonal columnar zinc oxide with the c-axis pointing upward can be grown. Furthermore, the quality of zinc oxide pillars,
That is, from the viewpoint of crystallinity, c-axis orientation, and the like, it is preferable to manufacture the film under conditions that form a hexagonal column. From such a viewpoint, in the hexagonal prism made of zinc oxide of the present invention, it is preferable that the hexagonal prism can be in the c-axis direction in the height direction, and it is preferable that the hexagonal prism be a single crystal.

Further, such a hexagonal zinc oxide column,
It is preferably composed of a zinc oxide column arranged in a direction with respect to the substrate, and can be formed, for example, substantially perpendicular to the substrate.

Although the shape and size of the zinc oxide column depend on the preparation conditions, the thickness is several nm to several μm, and the length is several tens.
nm to several tens of μm, and the aspect ratio is in the range of about 1 to 200.

The composition of zinc oxide in the present invention is not particularly limited as long as it contains oxygen and zinc as main components. B, A
By doping with l, Ga, In, N, P, As, or the like, carrier polarity, carrier density, and the like can be controlled. Furthermore, the emission level can be controlled by introducing impurities such as oxygen vacancies and rare earth elements.

As the substrate 2, an arbitrary single crystal substrate such as a sapphire substrate, a Si substrate, a GaN substrate, or a ZnO substrate, a glass substrate such as a quartz glass substrate, and an arbitrary thin film formed on these substrates Can be used. Although the zinc oxide column 1 may be directly disposed on such a substrate 3, disposing the conductive film 4 as an underlayer enables electrical connection using the conductive film as an electrode, such as a glass substrate. This is preferable because an inexpensive substrate can be used.

A photonic crystal can be obtained by arranging the above-described zinc oxide columns two-dimensionally on a substrate. The photonic crystal, as explained above,
It is composed of a structure in which at least different types of portions having different refractive indexes (dielectric constants) are periodically arranged. In order to control such a photonic band, the size of the structural period needs to be a size of about the wavelength of light to a fraction of the wavelength of light.

In the luminous body of the present invention, that is, in the photonic crystal in which zinc oxide is periodically arranged, 100 to 400 nm is required to control the emission from the ultraviolet region to the visible region.
Requires a periodic structure of a certain degree. In the present invention, the photonic band structure generated by the periodic structure produces effects such as a reduction in the density of states at the emission wavelength and anisotropy of the dispersion relation, but it is more preferable that the photonic band gap is widened. Examples of the periodic structure of the two-dimensional photonic crystal include a square arrangement and a triangular lattice arrangement. From the viewpoint of opening the photonic band gap, as shown in FIG. A triangular lattice arrangement is preferred. When a hexagonal zinc oxide pillar is applied to such a triangular lattice array,
It is more preferable to control the orientation of the array and the in-plane orientation of the hexagonal prism because their symmetries coincide. For example, as shown in FIG. 4A, an arrangement in which the direction connecting the periodic direction 11 of the triangular lattice 10 to the center 12 of the hexagonal prism (shape) and the vertex 13 coincides, or as shown in FIG. ) Coincides with the direction of the center 14 of the side surface and the center 15 of the side surface (side), thereby enhancing the anisotropy of the photonic band structure and the electron-light interaction caused by the matching of the orientation of the crystal field and the radiation field. Enables enhancement. Thereby, for example, when used as a light emitting element, it is possible to improve the luminous efficiency and the luminescent anisotropy.

<Production Method> Next, a method for producing a luminous body (structure) made of zinc oxide of the present invention will be described. Examples of the method for producing the zinc oxide column of the present invention include an MBE method, a laser deposition method, a CVD method, an in-solution growth method, a sputtering method, and a vacuum deposition method. Is preferred.

That is, as a method for producing the zinc oxide pillar of the present invention, it is preferable to use precipitation from a solution having zinc ions. By using zinc oxide growth in a solution, the above-described structure having a large area can be manufactured at low cost.
For example, a sample 31 is immersed in a reaction solution 32 composed of an aqueous solution of zinc nitrate and DMAB (dimethylamine borane) using a reaction apparatus as shown in FIG. 10 to form a zinc oxide film. By selecting appropriate conditions such as concentration and temperature and using an appropriate substrate, the above-described zinc oxide column can be grown. At this time, irradiation with ultraviolet light 34 can also be performed.

On the surface of the substrate, Pd, P
By adding a noble metal element such as t, Cu, Ag, Au, Rh, and Ir and an iron group element such as Ni, Fe, and Co, zinc oxide can be selectively grown on the catalyst-applied portion. Examples of the method for applying the catalyst include immersing the catalyst in a solution containing the above-described catalyst ions, and forming a film made of an element serving as a catalyst. However, in order to make the direction of the zinc oxide column stand upright on the substrate, it is preferable to use a substrate on which a continuous film of a material that can be a catalyst is formed as the conductive film. For example, there is a method of forming a continuous film of a noble metal such as Pt, Pd, and Cu. The use of such a substrate having a flat film mainly containing a noble metal as a main component is preferable because the zinc oxide column can be made to stand substantially perpendicularly to the substrate. Furthermore, this noble metal substrate is, for example, 11
Orientation in one direction or the like is preferable from the viewpoint of reducing variations in shape and density of the zinc oxide columns.

The noble metal film can be used as an electrode for supplying a current (applying a potential) to the zinc oxide column after growing the zinc oxide column. As a result, as shown in FIG. 1, it is possible to obtain a structure characterized by being composed of the base 2 and the zinc oxide columns 1 arranged with directionality to the base.

As a method of periodically arranging the zinc oxide pillars according to the present invention, first, a patterning method using an electron beam exposure and etching technique is used. To do this, create a desired pattern on the substrate in advance,
Growing zinc oxide pillars. For example, by performing the above-described submerged growth after patterning the periodic pores, zinc oxide columns can be grown from the respective pores.

However, such a method has problems such as poor yield and high device cost in patterning. Therefore, it is preferable to use a naturally formed regular nanostructure as described below. For example, an anodized alumina film may be used. Anodized alumina is
This is most preferable because a two-dimensional periodic structure having a high aspect ratio over a large area, that is, a 2D photonic crystal can be produced by a simple technique called anodic oxidation. In addition, the periodic size can be controlled in the range of several tens to 500 nm depending on the manufacturing conditions, so that it is useful for manufacturing a photonic crystal in the visible to ultraviolet region.

Further, by applying a production method using anodized alumina, a columnar zinc oxide having a nanometer size can be produced at a low cost by a simple production method.

The anodic alumina nanoholes will be described below. Anodized alumina nanoholes are produced by anodizing an Al film, aluminum foil, aluminum plate, or the like in a specific acidic solution (for example, RC Fur).
neaux, W.C. R. Rigby & A. P. Dav
idson "NATURE" Vol. 337, P147
(1989)). FIG. 8 shows a schematic diagram of anodized alumina nanoholes. This anodized alumina layer 52
It has a large number of cylindrical nanoholes (pores) 53 containing Al and oxygen as main components, and the nanoholes 53 are arranged almost perpendicularly to the surface of the substrate, and the nanoholes are arranged parallel to each other and at substantially equal intervals. are doing. That is, a structure (structure as a two-dimensional photonic crystal) in which column-shaped second dielectric parts (hollows) are regularly and two-dimensionally arranged in a honeycomb shape in the first dielectric parts (alumina). Have. The diameter 2r of the alumina nanohole is several nm to several hundreds.
The nm and the interval 2R are on the order of several tens of nm to several hundreds of nm, and can be controlled by anodic oxidation conditions. Further, the thickness of the alumina nanohole layer 52 and the depth of the nanoholes can be controlled by the anodic oxidation time and the like. This is for example between 10 nm and 500 μm. The pore diameter 2r of the alumina nanoholes can be increased by etching. For this, a phosphoric acid solution or the like can be used.

The pore arrangement can be regularized by a two-stage anodic oxidation method or a method in which honeycomb-shaped irregularities (pore starting points) are formed on the Al surface and then anodized. (Masuda: "OPTRONICS" No. 8 (1998) 21
(Refer to page 1.) Examples of a method of forming the pore starting point include a method using a stamper, a method of irradiating FIB, and the like.

In order to control the in-plane direction of the hexagonal column-shaped zinc oxide column, that is, the ab axis direction of the present invention, the patterning may be made hexagonal or a single crystal substrate may be used. This can be realized by matching the azimuth with the azimuth of the periodic structure. In addition, when a circular pattern (pores) is used, a certain orientation can be determined by setting the shape of the pattern to an elliptical pattern (pores). When applying anodized alumina, the shape of the pores can be controlled to some extent by the production conditions such as the shape of the pore starting point, the arrangement pattern, and the anodic oxidation conditions described below.

[0043]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 and Comparative Examples 1 and 2 This example is an example in which zinc oxide of hexagonal columns is formed in a triangular lattice arrangement by growth of zinc oxide by MBE and patterning using electron beam exposure.

First, a 200 nm-thick zinc oxide film was epitaxially grown on the degreased and cleaned c-plane sapphire substrate by MBE. In the MBE method, Zn metal and RF
After preheating at 650 ° C. in a vacuum using a (high frequency) oxygen radical source, the Zn partial pressure is 1 × 10 ⁻⁴ Pa (1 × 10 ⁻⁶ to
rr), O ₂ flow rate 0.3 ml / min (0.3 cc)
m), ZnO was grown under the conditions of RF power of 300 W and substrate temperature of 550 ° C.

Subsequently, a resist mask pattern was formed by resist film formation, electron beam exposure and development. The mask pattern has a shape as shown in FIG. 4A in which hexagons are arranged, and hexagons having a diameter of about 200 nm are arranged in a triangular lattice pattern at a period of 0.3 μm. Further, the periodic structure of the mask pattern was set to be in the [1-2-1] direction of the zinc oxide film. Subsequently, NH ₄ OH and H ₂ O ₂
Wet-etch zinc oxide with an etchant consisting of
Further, the resist was removed with an organic solvent.

Further, as Comparative Example 1, a zinc oxide film formed without patterning was prepared. Further, as Comparative Example 2, a mask pattern having a circular pattern instead of a hexagonal pattern was prepared.

(Evaluation) The sample of Example 1 was subjected to FE-SEM
Observation confirmed that hexagonal zinc oxide columns were formed in a triangular lattice arrangement according to the exposure pattern. The zinc oxide pillars were 160 nm in size and the hexagonal corners were slightly rounded, but had a regular hexagonal shape. On the other hand, Comparative Example 1 was a flat film. In Comparative Example 2, columnar zinc oxides were arranged. From the TEM observation, it was confirmed that the crystal had grown on the sapphire substrate.

An He-Cd laser is used as an excitation source (excitation wavelength 3
25 nm) and the photoluminescence measurement
In the samples of the present example and the comparative example, the wavelength was 385n.
m emission between bands and a wavelength of 500 to 55 due to oxygen deficiency.
Green light emission near 0 nm was confirmed.

The emission spectrum of the sample of Example 1 is mainly in the ultraviolet region as compared with the sample of Comparative Example 1, and
Green light emission was suppressed. It can be considered that green light emission was suppressed by the formation of the photonic band gap by the periodic structure. Further, the sample of Example 1 had a slightly higher photoluminescence intensity than the sample of Comparative Example 2. This can be considered to be the effect of the hexagonal periodic arrangement.

Example 2 and Comparative Example 3 This example is an example in which patterning by electron beam exposure and selective growth of zinc oxide by a solution process. FIG. 5 is a diagram showing a manufacturing process of the luminous body of this example. Hereinafter, FIG.
This will be described with reference to FIG.

Step a) A Pd film is formed as a base conductive film 4 on a substrate 3 made of a silicon substrate by RF sputtering.
A film was formed to a thickness of 0 nm. The conditions for forming the underlying conductive film are as follows:
It is preferable that the 111 orientation is excellent. For example, when forming a Pd film, the conditions of RF power 150 W and argon gas pressure 0.7 Pa (5 mtorr) were used. Here, RF sputtering was used, but the sputtering method, CV
Any film forming method can be applied to the D method, the vacuum evaporation method, and the like. (See FIG. 5 (a))

Step b) Successively, a resist mask 7 of a resist having circular openings arranged in a triangular lattice was formed by a resist film, electron beam exposure and development. The size of the opening is in the range of 50 to 400 nm, and the interval (period) of the opening is 10
Patterns with various aperture diameters and arrangement periods were formed in the range of 0 to 500 nm. (See FIG. 5 (b))

Step c) Using the apparatus shown in FIG. 10, the sample is irradiated with ultraviolet light from a high-pressure mercury lamp at a bath temperature of 60 ° C. in a reaction solution 32 consisting of an aqueous solution of 0.05M ZnNO ₃ and 0.05M dimethylamine borane. Below, a zinc oxide column 1 was grown. The processing time is 30 minutes. Thereby, the zinc oxide film is selectively grown on the conductive film. (FIG. 5
(See (c))

Step d) Finally, the resist mask was dissolved with an organic solvent. (See Fig. 5 (d))

As Comparative Example 3, a film prepared by growing zinc oxide without forming a resist mask on a conductive film was prepared.

(Evaluation) The sample of Example 2 was subjected to FE-SEM
Observation confirmed that hexagonal zinc oxide columns were formed in a triangular lattice arrangement in the circular mask pattern according to the opening size, as shown in an example in FIG. 9A.
Although the shapes of the hexagonal prisms were mixed with those of FIGS. 3A to 3C, the shape of the hexagonal corners was relatively sharp. For example, when a resist mask having an opening of 300 nm was used, the size of the hexagonal prism was about 200 to 250 nm, and the height was about 500 nm. X-ray diffraction confirmed that the zinc oxide was c-axis oriented.

In Comparative Example 3, hexagonal columnar zinc oxide also grew, but as shown in FIG. 9 (b), the size variation was large and the positions were random. At this time, by using the underlying conductive film with 111 orientation, ZnO having excellent c-axis and hexagonal columnar shape could be grown.

In particular, when an appropriate mask opening size was used, there was a tendency that a large amount of zinc oxide having excellent hexagonal column shape and size uniformity and a shape close to a regular hexagonal column was grown. . In this embodiment, the opening diameter is 400
nm, and the diameter of the ZnO hexagonal prism is 3 nm.
It was about 00 nm.

By measurement of photoluminescence using a He—Cd laser as an excitation source, in both samples of Example 2 and Comparative Example 3, emission between the band at a wavelength of 385 nm and green emission near a wavelength of 500 to 550 nm were confirmed. In the sample with a mask opening diameter of 200 nm and a cycle of 250 nm, the emission spectrum was mainly in the ultraviolet region and the green emission was suppressed as compared with the sample of Comparative Example 3. It can be considered that the green emission was suppressed by the formation of the photonic band gap.

Mask opening diameter 200 nm, period 250 nm
Using the sample, the laser emission threshold was evaluated at the liquid nitrogen temperature by exciting with the third harmonic of YAG and measuring the photoluminescence. As a result, the laser oscillation threshold of Example 3 was higher than that of Comparative Example 3. Was low. Example 3
In, it is considered that the laser oscillation threshold was reduced due to the effect of group velocity reduction as a photonic crystal.

Embodiments 3 and 4 In this embodiment, Pt (Embodiment 3) and C
Same as Example 2 except that u (Example 4) was used.

In the second embodiment, the mask opening diameter is 400
At about nm, the shape uniformity of the zinc oxide pillar was excellent, but in the present example using Pt as the underlying conductive film, the shape uniformity was desirable when the opening diameter was about 200 nm, and Cu was used as the underlying conductive film. Was preferred when an aperture diameter of about 100 nm was used. In each case, the diameter of the ZnO hexagonal prism is 150 nm, 60
nm. That is, by selecting an appropriate base conductive film, zinc oxide columns having excellent shape uniformity in various sizes could be grown.

In the third embodiment, the mask opening diameter is 200 n.
Using a sample having a period of 250 nm and a wavelength of 250 nm, the sample was excited by the third harmonic of YAG, photoluminescence was measured, and the laser oscillation threshold was evaluated at liquid nitrogen temperature. Threshold was low.

Further, in the fourth embodiment, the mask opening diameter 1
Photoluminescence was measured using a sample having a wavelength of 00 nm and a period of 150 nm and using a He-Cd laser as an excitation source. As a result, the photoluminescence intensity was higher than that of Example 2.

Embodiment 5 This embodiment is the same as Embodiment 3 except that the mask pattern is made elliptical instead of circular. The major axis ratio of the ellipse was 3: 4.

In this embodiment, as shown in FIG. 9C, the direction of the hexagonal prism tends to match the direction connecting the central axis and the apex with the major axis of the elliptical opening. In other words, the zinc oxide columns were arranged with hexagonal columns aligned. X-ray diffraction confirmed c-axis orientation and in-plane orientation of zinc oxide. When the photoluminescence intensity of the sample of this example was evaluated, it was slightly higher than that of Example 3.

Example 6 This is an example in which anodized alumina is used to form an array of zinc oxide columns. FIG. 6 and FIG. 7 are views showing the steps of manufacturing the luminous body of this example. This will be described below with reference to FIGS.

Step a) A Pd film is formed on a substrate 3 made of quartz glass by RF sputtering as a base conductive film 4.
After forming the film to a thickness of nm, an aluminum film 8 was further formed to a thickness of 1 μm by DC sputtering. The conditions for forming the underlying conductive film are 1
It is preferable that the 11 orientation is excellent. For example, RF power 150 W, argon gas pressure 0.7 Pa (5 mtorr)
The condition of r) was used. Here, RF sputtering and DC
Although sputtering is used, any film forming method such as a CVD method and a vacuum evaporation method can be applied to the film formation. (See FIG. 6 (a))

Step b) Next, as a step before anodic oxidation,
Irregularities are formed on the surface of the aluminum so as to be the starting point 9 of the pores for anodization. By this surface processing, the pore arrangement of alumina can be made regular. The irregularities are preferably formed in a honeycomb shape corresponding to the pore arrangement of the anodized alumina in order to produce nanoholes having a large aspect ratio. As a method of forming the pore starting point (concave portion), a method of irradiating a focused ion beam (FIB), a method of using SPM such as AFM,
Japanese Patent Application Laid-Open No. H10-112292 discloses a method of forming a dent using press patterning, a method of forming a dent by etching after forming a resist pattern, and the like.

Among these methods, the method using focused ion beam irradiation does not require complicated processes such as resist coating, electron beam exposure, and resist removal. Since it is possible to form a starting point and it is not necessary to apply pressure to the workpiece, it is particularly preferable from the viewpoint of being applicable to a workpiece having low mechanical strength.

In this embodiment, a dot-shaped starting point is formed in a honeycomb array at 200 nm intervals by irradiating a focused ion beam of Ga. Here, the ion species for focused ion beam processing was Ga, the acceleration voltage was 30 kV, the ion beam diameter was 100 nm, the ion current was 300 pA, and the irradiation time for each dot was 10 msec. (FIG. 6 (b)
reference)

Step c) Next, anodized alumina 5 is prepared by anodizing the above aluminum film. FIG.
Medium, 40 is a thermostat, 41 is a sample, 42 is a cathode of a Pt plate, 43 is an electrolyte, 44 is a reaction vessel, and 45 is a reaction vessel.
Is a power supply for applying an anodizing voltage, 46 is an ammeter for measuring anodizing current, and 47 is a sample holder. Although not shown in the figure, a computer for automatically controlling and measuring the voltage and current is incorporated. The sample 41 and the cathode 42 are disposed in an electrolyte maintained at a constant temperature by a constant temperature water bath, and anodic oxidation is performed by applying a voltage between the sample and the cathode from a power supply. Examples of the electrolyte used for anodic oxidation include oxalic acid, phosphoric acid, sulfuric acid, and chromic acid solution.

Since the pore spacing of alumina nanoholes, that is, the structural period has a correlation with the anodic oxidation voltage substantially according to the following equation (1), it is desirable to set the anodic oxidation voltage in accordance with the starting point arrangement (interval).

[0075]

(Equation 1)

The thickness of the alumina nanoholes can be controlled by the thickness of the aluminum film and the time of anodic oxidation. For example, the entire thickness can be replaced with alumina nanoholes, or a desired aluminum film can be left.

Further, the diameter of the nanoholes can be appropriately increased by immersing the alumina nanohole layer in an acid solution (for example, a phosphoric acid solution) (pore widening process). Alumina nanoholes having a desired nanohole diameter can be obtained by controlling the acid concentration, the processing time, and the temperature.

In this example, anodizing was performed at 80 V using a 0.3 M phosphoric acid bath as an electrolytic solution for anodic oxidation. As a pore wide treatment, phosphoric acid solution 5w at 25 ° C
t. % For about 160n
m. (See FIG. 7 (c))

Step d) Zinc oxide pillars 1 were grown from the bottoms of the pores in the same manner as in Example 2. However, the concentration of ZnNO ₃ was 0.02 M, the bath temperature was 70 ° C., and the reaction time was 2
Time. (Refer to FIG. 7 (d)) (Evaluation) The sample of Example 6 was observed by FE-SEM to form hexagonal zinc oxide columns in a triangular lattice arrangement in the pores of anodized alumina according to the pore size. Confirmed that. Although the shapes of the hexagonal prisms were mixed with those of FIGS. 3A to 3C, the shape of the hexagonal corners was relatively sharp.

The height of the zinc oxide column of Example 6 was 1
Zinc oxide pillars having a height of about μm and a high aspect ratio could be formed. In addition, a large area array pattern could be formed by a simple method.

Photoluminescence measurement using a He—Cd laser as an excitation source showed that the emission between the band of 385 nm and the wavelength of 500 to 550 nm were observed in both samples.
Near green emission was confirmed.

The emission spectrum of the sample of Example 6 is mainly in the ultraviolet region compared to the sample of Comparative Example 3, and
Green light emission was suppressed. It can be considered that the green emission was suppressed by the formation of the photonic band gap.

The sample of Example 6 was subjected to 40
After performing heat treatment at 0 ° C. for 1 hour, and further depositing an amount of Ag equivalent to a thickness of 100 nm, the resultant was placed in a vacuum apparatus and 10 ^−6.
After evacuation to Pa, the temperature was cooled to the temperature of liquid nitrogen, and L
electrons are emitted from the electron gun consisting aB _6, the acceleration voltage 1
When an electron beam accelerated to 0 to 50 keV is irradiated,
Laser oscillation was possible in the ultraviolet region around 390 nm. Laser oscillation threshold 10-15A / c
m ² .

On the other hand, when the same evaluation was performed in Comparative Example 3, the oscillation threshold was about ²⁰ to 40 A / cm ² . The threshold current density was reduced by using the luminous body of the sixth embodiment. Further, the laser oscillation wavelength width was narrow, and the number of laser oscillation modes was reduced. In the present embodiment, it is considered that the laser oscillation threshold value is reduced by the effect of the group velocity reduction.

Example 7 The samples prepared in Examples 2 to 4 were subjected to a heat treatment at 600 ° C. for 10 minutes in a reducing atmosphere of 2% H ₂ and 98% He to obtain an oxygen composition in the zinc oxide column. After reducing the amount and increasing the conductivity, the electron emission ability was evaluated.

The sample was placed in a vacuum device, and 10^-6Pa
After exhausting by applying voltage to the opposed anode plate
The electron emission amount was evaluated. The distance between the anode and the sample is 2m
m, and the voltage was 5 kV. Using Cu of Example 4 as a base
Of the sample with the thinnest zinc oxide pillars
Highest electron emission ability, 4μA / cm
^Two It was about. That is, according to the method of this embodiment,
Electron-emitting devices in which no-sized zinc oxide columns are arranged
I knew it would work.

[0087]

As described above, the present invention has the following effects. According to the luminous body and structure of the present invention, 1) by arranging a zinc oxide pillar having excellent crystallinity and a nano-sized diameter on a substrate, a high-efficiency luminous body could be obtained. 2) Further, by arranging the zinc oxide pillars periodically at a submicron size in this manner, an effect was obtained in which the photonic crystal can be applied to optical elements such as light-emitting elements.

Further, according to the manufacturing method of the present invention, 3) the above-mentioned structure having a large area can be manufactured at low cost by using zinc oxide growth in a solution. 4) Further, anodized alumina is applied. By applying the manufacturing method described above, it was possible to produce a structure in which columnar zinc oxide was periodically arranged on the substrate at a low cost with a simple manufacturing method, and the effect was obtained.

The luminous body using the zinc oxide column of the present invention can be used for a phosphor, a display device and the like. Moreover,
The zinc oxide column of the present invention can be used in a wide range as a functional material or a structural material such as an electronic device or a micro device. In particular, examples of the functional material include a photoelectric conversion element, a photocatalyst element, and an electron emission material. No.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a light-emitting body (structure) on which a zinc oxide pillar of the present invention is arranged.

FIG. 2 is a conceptual diagram showing a zinc oxide column of the present invention.

FIG. 3 is a perspective view showing a zinc oxide column of the present invention.

FIG. 4 is a conceptual diagram showing an arrangement of zinc oxide columns in the luminous body of the present invention.

FIG. 5 is a process diagram showing a process for manufacturing a light-emitting body according to Example 2 of the present invention.

FIG. 6 is a process chart showing a process for producing a light-emitting body using anodized alumina of Example 6 of the present invention.

FIG. 7 is a process chart showing a process for producing a light-emitting body using anodized alumina of Example 6 of the present invention.

FIG. 8 is a schematic diagram showing anodized alumina in the present invention.

FIG. 9 is a view showing an example of the structure of a zinc oxide pillar of Example 2, Comparative Example 3, and Example 5 of the present invention.

FIG. 10 is a schematic diagram showing a zinc oxide growth apparatus by a solution process of the present invention.

FIG. 11 is a schematic view showing an anodizing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Zinc oxide pillar 2 Substrate 3 Substrate 4 Conductive film 5 Anodized alumina 6 Pores 7 Resist mask 8 Aluminum film 9 Pores starting point 10 Triangular lattice 11,16 Periodic direction 12,14 Center of hexagonal column (shape) 13 Vertex 15 Center of surface 30 Thermostat 31 Sample 32 Reaction solution 33 Reaction vessel 34 Ultraviolet light 40 Thermostat 41 Sample 42 Cathode 43 Electrolyte 44 Reaction vessel 45 Power supply 46 Ammeter 47 Sample holder 51 Aluminum (membrane) 52 Anodized alumina 53 Pore ( Nanohole) 54 Barrier layer

Claims (16)

[Claims] 1. A semiconductor device comprising: a base; and a plurality of columnar members containing zinc oxide as a main component, wherein the columnar members are substantially hexagonal prism-shaped and substantially perpendicular to the surface of the substrate. A light emitter characterized by being arranged. 2. The luminous body according to claim 1, wherein the plurality of columnar members containing zinc oxide as a main component are arranged substantially periodically. 3. The arrangement period of the periodically arranged zinc oxide columns is smaller than an emission wavelength.
The luminous body according to item 1. 4. The luminous body according to claim 1, wherein said zinc oxide pillars are arranged in a triangular lattice. 5. The zinc oxide column has a substantially regular hexagonal cross-section, and the arrangement orientation of the periodic structure is substantially equal to the direction from the column center to the vertex direction of the hexagonal column-shaped zinc oxide column. The luminous body according to any one of claims 2 to 4, wherein: 6. The luminous body according to claim 5, wherein an arrangement orientation of the periodic structure is substantially equal to a direction from a pillar center of the hexagonal pillar-shaped zinc oxide pillar to a center of a side surface. 7. The luminous body according to claim 1, wherein the base comprises a substrate and a conductive film on the substrate. 8. The light emitting device according to claim 7, wherein said conductive film contains Pt, Cu or Pd as a main component. 9. The method according to claim 1, wherein the conductive film is perpendicular to the substrate.
The luminous body according to claim 8, wherein the luminous body is oriented in 11 directions. 10. The luminous body according to claim 1, wherein the zinc oxide column is oriented in a c-axis direction perpendicular to the substrate. 11. The luminous body according to claim 1, wherein said zinc oxide columns are arranged in pores of anodized alumina. 12. A structure comprising: a base; and a hexagonal column-shaped zinc oxide column disposed on the base in a periodically upright manner. 13. The structure according to claim 12, wherein the base comprises a substrate and a conductive film on the substrate. 14. A step of forming a conductive film on a substrate to form a base, forming a pattern of periodically arranged circular or elliptical pores on the base, 14. The method according to claim 1, further comprising a step of growing a zinc oxide column in a solution containing zinc ions in the pores. 15. The method according to claim 14, wherein the pores are elliptical. 16. The step of forming a pattern of circular or elliptical pores includes forming a pore formation start point on the surface of aluminum provided on a substrate, and anodizing the aluminum. 15. The method according to claim 14, further comprising a step of forming anodized alumina having pores.
6. The method for producing a luminous body according to 5.