JP2008290028A - Light source-integrated photocatalytic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst layer also with an electrode function of light emitting diode. <P>SOLUTION: The light source-integrated photocatalytic apparatus 100 has a light emitting layer 13 comprising InGaN. A light-transmissive electrode 20 comprising niobium titanium oxide and having a photocatalytic function is formed on a p-clad layer 14 comprising p-type AlGaN and a p-contact layer 15 comprising p-type GaN. The light-transmissive electrode 20 comprising niobium titanium oxide acts as a photocatalytic function layer by being activated by an ultraviolet light of wavelength of 380 nm from the light emitting layer 13, and also acts as a light-transmissive electrode for supplying current to the light emitting layer 13. The part functioning as a photocatalyst is a part in the vicinity of the exposed surface 20s of the light-transmissive electrode 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a light source integrated photocatalytic device in which a photocatalytic function and a light source that emits light for activating the photocatalyst are integrated. In the present application, the group III nitride compound semiconductor is a semiconductor represented by Al _x Ga _y In _1-xy N (where x, y, and x + y are all 0 or more and 1 or less), n-type / p-type, etc. For which any element is added. Furthermore, it includes those in which a part of the composition of the group III element and the group V element is substituted with B, Tl; P, As, Sb, Bi.

A technique for removing or reducing toxic substances and odorous substances in waste water or air by using an ultraviolet light source having a wavelength of 410 nm or less and a photocatalytic layer having a photocatalytic function such as titanium oxide (TiO ₂ ) is widely known. . By the way, if the light source for activating the photocatalyst and the photocatalytic functional material are arranged separately, it is difficult to reduce the size, and the utilization efficiency of light emitted from the light source is poor. Therefore, as a technique for integrating the light source and the photocatalyst, the technique disclosed in Patent Document 1 is known.

In addition, a technique for imparting conductivity to titanium oxide (TiO ₂ ) has recently been reported by the present inventors (Patent Document 2).
JP 2000-037615 A WO2006 / 073189

In the technique described in Patent Document 1, there is a transparent protective layer between the light source and the photocatalyst layer, and light utilization efficiency may be reduced due to total reflection at the interface and absorption by the transparent protective layer.
Accordingly, the present inventors have conceived of having the electrode function of a light emitting diode while using titanium oxide (TiO ₂ ) as a photocatalytic layer, and completed the present invention.

The invention according to claim 1 is a light source integrated photocatalytic device in which a photocatalytic functional layer and an ultraviolet light source having a laminated structure of a group III nitride compound semiconductor are integrated, wherein the photocatalytic functional layer includes niobium (Nb), From titanium oxide doped with tantalum (Ta), molybdenum (Mo), arsenic (As), antimony (Sb), aluminum (Al) or tungsten (W) at a molar ratio of 1 to 10% with respect to titanium (Ti). In addition, the photocatalytic function layer constitutes an electrode for supplying a current to the ultraviolet light source, and is a light source integrated photocatalyst device.
The invention according to claim 2 is that the photocatalytic functional layer is composed of niobium titanium oxide or tantalum titanium oxide in which niobium (Nb) or tantalum (Ta) has a molar ratio of 3 to 10% with respect to titanium (Ti). Features.

The invention according to claim 3 is characterized in that a layer made of another material does not exist between the photocatalytic functional layer and the group III nitride compound semiconductor layer as the contact layer.
In the invention according to claim 4, the ratio between the refractive index of the photocatalytic functional layer and the refractive index of the group III nitride compound semiconductor layer that is the contact layer is 0.98 or more and 1.02 or less. It is characterized by.
In the invention according to claim 5, there is only a translucent conductive layer made of another material and having a thickness of 100 nm or less between the photocatalytic functional layer and the group III nitride compound semiconductor layer as the contact layer. It is characterized by doing. Here, the translucent conductive layer is not limited to a single layer, and includes a multi-layered film having a total film thickness of 100 nm or less. Further, the “translucency” may be at least substantially transparent to light emitted from the ultraviolet light source.

The invention according to claim 6 is characterized in that the photocatalytic functional layer is a p-electrode, and the invention according to claim 7 is characterized in that the photocatalytic functional layer is an n-electrode.
The invention according to claim 8 is characterized in that a highly reflective layer is provided on the side opposite to the photocatalytic functional layer with respect to the light emitting layer of the ultraviolet light source. In the invention according to claim 9, the photocatalytic functional layer is a double layer of a doped titanium oxide layer and a titanium oxide layer or a titanium oxynitride layer that is intentionally not doped with impurities. It is characterized by comprising. The invention according to claim 10 is characterized in that the photocatalytic functional layer has irregularities on the surface.

Doping with niobium (Nb), tantalum (Ta) or other impurities greatly reduces the resistivity of titanium oxide (TiO ₂ ). Here, when titanium (Ti) of titanium oxide (TiO ₂ ) is replaced by 3 to 10% with niobium (Nb) or tantalum (Ta), the refractive index with respect to light with a wavelength of 360 nm to 600 nm becomes almost equal to that of gallium nitride. This has been newly found by the present inventors. FIG. 5 shows a refractive index for light having a wavelength of 400 nm to 800 nm when the tantalum composition x of tantalum titanium oxide (Ti _1-x Ta _x O ₂ ) is changed in six steps from 0.01 to 0.2. It is a graph which shows dispersion | distribution of. The same applies to the case where niobium (Nb) or other impurities are added. On the other hand, according to, for example, Isao Akasaki, Baifukan, Advanced Electronics Series I-21 “Group III Nitride Semiconductor”, page 57, FIG. 3.12, the refractive index of GaN is about 2.74 at a wavelength of 370 nm and at a wavelength of 400 nm. It is about 2.57, about 2.45 at a wavelength of 500 nm, and about 2.40 at a wavelength of 600 nm.

The present inventors have already found that when 1 to 10% of niobium (Nb), tantalum (Ta) or other impurities are added to titanium oxide (TiO ₂ ), the resistivity is about 5 × 10 ⁻⁴ Ωcm or less. (Patent Document 2).
Therefore, for example, titanium oxide (TiO ₂ ) added with 1 to 10% of niobium (Nb), tantalum (Ta) or other impurities can be used as an electrode of a group III nitride compound semiconductor, and the wavelength is 360 nm. It becomes possible to substantially eliminate total reflection at the interface between ˜600 nm light and, for example, a gallium nitride layer and a doped titanium oxide (TiO ₂ ) layer. As shown below, for example, when the refractive index of doped titanium oxide (TiO ₂ ) is made larger than the refractive index of gallium nitride at a wavelength of 410 nm or less in the near ultraviolet region, for example, niobium (Nb) or tantalum (Ta It is possible by adjusting the doping amount of other impurities. Thereby, for example, ultraviolet light incident on a titanium oxide (TiO ₂ ) layer doped from a gallium nitride layer can be prevented from being emitted to the gallium nitride layer by total reflection.
In addition to gallium nitride, a group III nitride compound semiconductor having an arbitrary composition can be used as the contact layer directly bonded to the translucent electrode. It is known that the refractive index of a group III nitride compound semiconductor changes depending on the composition ratio of group III elements and the concentration of impurities to be added. It is most desirable to adjust the addition of niobium (Nb), tantalum (Ta) or other impurities to titanium oxide (TiO ₂ ) so that the refractive index of the contact layer to be directly bonded matches. In this case, total reflection does not occur at all. In order to reduce total reflection even if not completely matched, the refractive index ratio is desirably 0.95 to 1.05, more desirably 0.98 to 1.02, and even more desirably 0.99 to 1.01. . At this time, although the refractive index change is large with respect to the change of the addition amount of niobium (Nb), tantalum (Ta) or other impurities to titanium oxide (TiO ₂ ) in the range of 1 to 10%, the conductivity (resistivity) is large. ) Is relatively small, it is possible to determine the amount of addition so that the refractive index becomes a desired value with the electric conductivity almost maximized (with the resistivity almost minimized).
In this way, a titanium oxide (TiO ₂ ) layer having a desired refractive index and a sufficiently reduced resistivity by adjusting the doping amount of niobium (Nb), tantalum (Ta), or other impurities is converted into the titanium oxide (TiO ₂ ) layer. Can be used as an electrode of a group III nitride compound semiconductor light emitting device having an emission wavelength that can be activated as a photocatalyst, thereby forming a light source integrated photocatalytic device in which a photocatalytic functional layer and an ultraviolet light source are integrated. it can. The light source integrated photocatalyst device of the present invention can make the distance between the photocatalyst functional layer and the ultraviolet light source, in particular, the distance from the ultraviolet light emitting layer to the photocatalyst functional layer extremely small. Specifically, it can be several μm or less, further about 300 nm or less, or about 100 nm. Thereby, the ultraviolet-ray emitted from a light emitting layer has little absorbed amount, can reach a photocatalyst functional layer efficiently, and the utilization efficiency of an ultraviolet-ray improves.

  In addition, the light source integrated photocatalytic device can be miniaturized and the manufacturing process can be simplified. Since the light utilization efficiency is high, the catalyst function can be improved and the life of the apparatus can be extended by reducing the input power.

Formation of a doped titanium oxide (TiO ₂ ) layer having two functions of an electrode and a photocatalytic function layer is performed by using, for example, sputtering or any other technique in addition to pulse laser deposition described in Patent Document 2. Can do. The target is titanium oxide (TiO ₂ ) and niobium oxide (Nb ₂ O ₃ ) or titanium oxide (TiO ₂ ) and tantalum oxide (Ta ₂ O ₅ ), and titanium (Ti) atoms and niobium (Nb) atoms. It is preferable to prepare a sintered target in which the molar ratio or the molar ratio of titanium (Ti) atoms and tantalum (Ta) atoms is a desired ratio. The sintered target made of the mixture is formed by heating the oxides after mixing them as fine powders. Further, the target includes a Ti—Nb alloy adjusted so that the molar ratio of titanium (Ti) atoms and niobium (Nb) atoms, or the molar ratio of titanium (Ti) atoms and tantalum (Ta) atoms becomes a desired ratio, A Ti—Ta alloy may be used to form a film by a reactive sputtering method.
For example, the amount of tantalum (Ta) or niobium (Nb) added to titanium oxide (TiO ₂ ) that matches the refractive index of 2.74 of gallium nitride (GaN) near a wavelength of 370 nm is preferably 3 to 10%. It is better to set it to -10%. Similarly, the addition amount of tantalum (Ta) or niobium (Nb) to titanium oxide (TiO ₂ ) that matches the refractive index of 2.57 of gallium nitride (GaN) near a wavelength of 400 nm is preferably 3 to 10%. Is more preferably 6 to 10%.

The titanium oxide (TiO ₂ ) layer may be a rutile type having a higher density or an anatase type having a lower density. From the viewpoint of lowering resistance, the anatase type is more preferable. In the case of the rutile type, the ultraviolet light source is designed so that the emission wavelength of the ultraviolet light source is 415 nm or less, and in the case of the anatase type, the emission wavelength of the ultraviolet light source is 380 nm or less. The light emitting layer made of a group III nitride compound semiconductor serving as an ultraviolet light source may be any of a single light emitting layer, a single quantum well layer (SQW), and a multiple quantum well layer (MQW). For example, when InGaN is used as the light emitting layer or well layer, when the indium (In) composition is 5.5% or less, a light emitting layer or well layer emitting near ultraviolet light having a wavelength of 380 nm or less can be obtained.

Further, when the titanium oxide (TiO ₂ ) layer is doped with nitrogen, the photocatalytic function can be exhibited even at a wavelength in the visible light region. At this time, the emission wavelength of the light source may be in the visible region. Then, the light source integrated photocatalytic device of the present invention can also have an illumination function. Alternatively, the outside of the light source integrated photocatalyst device of the present invention is provided with a phosphor cover having a gas or liquid inflow / outflow path to be purified, thereby converting the leaked ultraviolet light into visible light for illumination. It can also be used.

In general, after epitaxial growth of a group III nitride compound semiconductor light emitting device having a p-side as the uppermost layer, an electrode made of titanium oxide (TiO ₂ ) doped on the p layer, a photocatalytic functional layer, When the layer having the two functions is formed, an electrode made of doped titanium oxide (TiO ₂ ) becomes a p-electrode. At this time, if a Bragg reflection layer composed of a highly reflective metal layer or multiple layers is formed on the back surface of the epitaxial growth substrate, it is possible to effectively use ultraviolet rays that are scattered on the back surface side of the epitaxial growth substrate.
Further, if the exposed surface of the electrode made of doped titanium oxide (TiO ₂ ) is provided with irregularities, the area of the exposed surface that functions as a photocatalyst can be increased. As the method for forming the unevenness, for example, etching, nanoimprinting, electron beam drawing, joining of fine particles of titanium oxide (TiO ₂ ), or any other known technique can be used.
When etching is used, the following is preferable. First, a resist mask is patterned by photolithography. Examples of the pattern include dots or lattices, stripes, and the like. At this time, the presence or absence of periodicity is also arbitrary. The width and pitch (interval) of the mask is preferably 3 μm or less. When the emission wavelength is λ and the refractive index of an electrode made of doped titanium oxide (TiO ₂ ) is n, the width and pitch (interval) of the mask is preferably λ / (4n) to λ. Thus, the unmasked window is etched (dry or wet, optionally selected). The depth is preferably 1 to 3 times the pitch, and at least λ / (4n) is required.
As another method for forming irregularities, conditions that allow irregularities to be generated when forming a TiO ₂ film are used, TiO ₂ is etched without forming a mask to form random minute irregularities, and a photo is formed on the TiO ₂ film. It is said that a resist mask pattern is formed, a TiO ₂ film is formed again, and then unnecessary portions are lifted off together with the mask, and after the TiO ₂ film is formed, random irregularities are formed on the surface by heat treatment. A method may be adopted.

As is well known, there is a technique for removing the epitaxial growth substrate. In this case, another support substrate is bonded to, for example, the p layer side, and the epitaxial growth substrate on the n layer side is removed, so that the n layer becomes the surface. Therefore, when a layer having two actions of an electrode made of doped titanium oxide (TiO ₂ ) and a photocatalytic function layer is formed on the n layer, the electrode made of doped titanium oxide (TiO ₂ ) is an n electrode. It becomes. In this case, when the support substrate is bonded to the p layer, if a Bragg reflection layer made of a highly reflective metal layer or multiple layers is formed between them, it is possible to effectively use the ultraviolet rays that are scattered to the support substrate side. Become.

By the way, titanium oxide (TiO ₂ ) doped with tantalum (Ta) or niobium (Nb) or other impurities and having conductivity may have a reduced photocatalytic function as compared with undoped titanium oxide (TiO ₂ ). Concerned. Therefore, by laminating an undoped titanium oxide (TiO ₂ ) layer on the surface of titanium oxide (TiO ₂ ) doped with tantalum (Ta), niobium (Nb), or other impurities, the device element is obtained. A decrease in the photocatalytic function can be prevented. The reason is described below.
As is generally well-known, in a transparent oxide film doped with impurities to increase the carrier concentration, a wavelength (optical absorption edge) at which a BM (Burstein-Moss) shift appears and light absorption rapidly increases, It moves to the shorter wavelength side than the undoped film. For this reason, if the absorption edges at the ultraviolet wavelength of undoped titanium oxide (TiO ₂ ) and doped titanium oxide (TiO ₂ ) are λ _ud and λ _d , λ _ud is several nm to several tens nm from λ _d. It becomes a large value. If the emission wavelength λ in the light emitting layer is set to satisfy λ _d <λ <λ _ud , most of the light emitted from the light emitting layer is not absorbed by the doped titanium oxide (TiO ₂ ) layer. It can be incident on an undoped titanium oxide (TiO ₂ ) layer. For undoped titanium oxide (TiO ₂ ) layers, light of wavelength λ is light below the optical absorption edge, so most of it is absorbed, and a high photocatalytic function is manifested on the surface of undoped titanium oxide (TiO ₂ ) layers. Is done. Thus, the electrode structure formed by laminating a titanium oxide (TiO ₂₎ layer of undoped over doped titanium oxide (TiO ₂₎ layer, if doped titanium oxide (TiO ₂₎ layer of photocatalytic function is not sufficient Even in this case, a high photocatalytic function can be exhibited by effectively using light from the light emitting layer.

FIG. 1 is a cross-sectional view showing a configuration of a light source integrated photocatalyst device 100 according to a first specific example of the present invention. In the light source integrated photocatalyst device 100, a buffer layer having a thickness of about 15 nm made of aluminum nitride (AlN) (not shown) is provided on a sapphire substrate 10, and an n-contact layer 11 made of silicon (Si) -doped GaN. Is formed. On the n-contact layer 11, an n-cladding layer 12 made of silicon (Si) -doped AlGaN is formed.
A light emitting layer 13 made of InGaN is formed on the n-clad layer 12. A p-clad layer 14 made of p-type AlGaN is formed on the light emitting layer 13. Further, on the p-cladding layer 14, a p-contact layer 15 having a laminated structure of two p-type GaN layers having different magnesium concentrations is formed.

  Further, a translucent electrode 20 made of niobium titanium oxide (niobium 6%) having a photocatalytic function is formed on the p contact layer 15, and an electrode 30 is formed on the exposed surface of the n contact layer 11. The electrode 30 is made of vanadium (V) having a thickness of about 20 nm and aluminum (Al) having a thickness of about 2 μm. An electrode pad 25 made of a gold (Au) alloy is formed on a part of the translucent electrode 20.

The translucent electrode 20 made of niobium titanium oxide and having a photocatalytic function is formed into a thickness of 0.05 to 1 μm by sputtering or other methods. At this time, in order to prevent an increase in lateral diffusion resistance, the thickness must be at least 0.05 μm. Note that substantially only the ultraviolet light that has reached the vicinity of the exposed surface 20s of the translucent electrode 20 acts on the photocatalytic function, so that the translucent electrode 20 made of niobium titanium oxide and having the photocatalytic function is at least A certain degree of transparency with respect to the emission wavelength from the light emitting layer 13 is required.
The photocatalytic function and the illumination function can be compatible by controlling the film thickness. At this time, the transmitted ultraviolet light may be visible light, for example, with a phosphor disposed outside. Further, the rutile type / anatase type of the translucent electrode 20 having a photocatalytic function may be selected according to the light wavelength and light output of the light emitting layer 13, but the anatase type is more preferable from the viewpoint of resistivity.

  The light source integrated photocatalyst device 100 of FIG. 1 is formed into a chip in the same manner as a normal light emitting diode. At this time, the surface 20s of the translucent electrode 20 made of niobium titanium oxide and having a photocatalytic function is exposed without being covered with a protective film or the like. Thus, the translucent electrode 20 made of niobium titanium oxide is activated by the ultraviolet light having a wavelength of 380 nm from the light emitting layer 13 to act as a photocatalytic functional layer and supply a current to the light emitting layer 13. Also works. At this time, what actually functions as a photocatalyst is in the vicinity of the exposed surface 20 s of the translucent electrode 20.

  FIG. A is a sectional view showing a configuration of a light source integrated photocatalyst device 200 according to a second specific example of the present invention. In this embodiment, the surface of the translucent electrode 20 functioning as a photocatalyst is provided with irregularities, and a surface 20s' having exposed irregularities is obtained. By providing the unevenness, the area of the exposed surface 20s' having the unevenness is increased. As a result, FIG. The light source integrated photocatalyst device 200 of A has a significantly improved photocatalytic function than the light source integrated photocatalytic device 100 of FIG. The method for forming the unevenness is arbitrary.

  In addition, by providing unevenness on the surface of the translucent electrode 20, the lateral diffusion resistance increases, and the function of the translucent electrode 20 as an electrode may be weakened. In this case, the configuration of the following modification may be employed. FIG. B is a cross-sectional view illustrating a configuration of a light source integrated photocatalyst device 210 according to a modification. FIG. The light source integrated photocatalyst device 210 of B is shown in FIG. A light source integrated photocatalyst device 200 of A comprising a light-transmitting conductive layer 21 made of indium tin oxide (ITO) between a light-transmitting electrode 20 made of niobium titanium oxide having a photocatalytic function and a p-contact layer 15 It is. According to this configuration, since the translucent conductive layer 21 made of niobium titanium oxide and having a resistivity lower than that of the translucent electrode 20 having a photocatalytic function is interposed, the translucent electrode 20 having a photocatalytic function alone is used. As a result, the lateral diffusion resistance of the anode can be suppressed, and the contact resistance with the p-type GaN layer 15 can be reduced. At this time, as the translucent conductive layer 21, in addition to indium tin oxide (ITO), any conductive oxide, conductive nitride, or metal can be used. However, those that absorb at least ultraviolet light are preferable, and the film thickness is preferably ¼ or less and 100 m or less of the wavelength of the ultraviolet light.

  FIG. 3 is a cross-sectional view showing a configuration of a light source integrated photocatalyst device 300 according to a specific third embodiment of the present invention. In the present embodiment, a configuration in which the reflective layer 40 is provided on the back surface of the sapphire substrate 10 of the light source integrated photocatalyst device 100 of FIG. 1 is adopted. As the reflective layer 40, a highly reflective metal film such as aluminum (Al) or a DBR film can be employed. Thereby, the ultraviolet light emitted from the light emitting layer can be efficiently used in the photocatalytic function.

  FIG. 4 is a cross-sectional view showing a configuration of a light source integrated photocatalyst device 400 according to a fourth specific example of the present invention. In the present embodiment, a group III nitride compound semiconductor layer is laminated on the sapphire substrate 10 in the same manner as in the formation of the light source integrated photocatalyst device 100 of FIG. 1, and then the reflective layer 40 and the electrode layer 60 are provided on both sides. Using the conductive support substrate 50, the side of the conductive support substrate 50 on which the reflective layer 40 is provided is adhered to the p contact layer 15, and then the sapphire substrate 10 is removed by, for example, a lift-off method using a laser to expose the exposed n contact. The layer 11 is provided with a translucent electrode 20 made of niobium titanium oxide and having a photocatalytic function. The translucent electrode 20 and the pad electrode 25 having a photocatalytic function serve as a cathode.

FIG. 6 is a cross-sectional view showing a configuration of a light source integrated photocatalyst device 500 according to a fifth specific example of the present invention. The light source integrated photocatalyst device 500 of FIG. 6 is characterized in that a photocatalytic layer 21 made of undoped titanium oxide is further laminated on the surface of the translucent electrode 20, as compared with the light source integrated photocatalyst device 100 of FIG. To do. On the surface 21s of the photocatalyst layer 21 made of undoped titanium oxide, the photocatalytic function of titanium oxide does not deteriorate due to impurities. Further, as already described, the wavelength λ between the optical absorption edge λ _ud of the photocatalytic layer 21 made of undoped titanium oxide and the optical absorption edge λ _d (<λ _ud ) of the translucent electrode 20 is set to the light emitting layer 13. It is better to emit.

FIG. The light-transmitting conductive layer 21 made of ITO of the light source integrated photocatalyst device 210 shown in B is configured by adding to the light source integrated photocatalytic devices 100, 300, and 400 of FIGS. Also good. Thereby, the lateral diffusion resistance of the electrode and the contact resistance with the p-type GaN layer 15 can be reduced.
The reflective layer 40 of the light source integrated photocatalyst device 300 shown in FIG. A, FIG. The light source integrated photocatalyst devices 100, 200, and 210 of B may be added in the same manner. Thereby, the ultraviolet light dissipated on the back surface of the substrate 10 can be effectively used.
In each example, niobium (Nb) was added to titanium oxide alone, but tantalum (Ta) may be added to titanium oxide alone, or niobium (Nb) and tantalum (Ta) may be added simultaneously. Also good.

  INDUSTRIAL APPLICABILITY The present invention is useful as a catalyst device that removes or reduces organic substances, nitrogen oxides, sulfur oxides, other toxic substances, malodorous substances, bacteria, and other microorganisms in waste water or air.

1 is a cross-sectional view showing a configuration of a light source integrated photocatalyst device 100 according to a first specific example of the present invention. Sectional drawing (2.A) which shows the structure of the light source integrated photocatalyst apparatus 200 which concerns on the specific 2nd Example of this invention, and sectional drawing which shows the structure of the light source integrated photocatalyst apparatus 210 which concerns on the modification ( 2.B). Sectional drawing which shows the structure of the light source integrated photocatalyst apparatus 300 which concerns on the specific 3rd Example of this invention. Sectional drawing which shows the structure of the light source integrated photocatalyst apparatus 400 which concerns on the specific 4th Example of this invention. The graph which shows dispersion | distribution of the refractive index at the time of changing a tantalum composition of a tantalum titanium oxide. Sectional drawing which shows the structure of the light source integrated photocatalyst apparatus 500 which concerns on the specific 5th Example of this invention.

Explanation of symbols

13: Ultraviolet light emitting layer 20: Translucent electrode having a photocatalytic function made of niobium titanium oxide 40: Reflecting layer

Claims (10)

In a light source integrated photocatalytic device in which a photocatalytic functional layer and an ultraviolet light source having a laminated structure of a group III nitride compound semiconductor are integrated,
The photocatalytic functional layer has a molar ratio of niobium (Nb), tantalum (Ta), molybdenum (Mo), arsenic (As), antimony (Sb), aluminum (Al), or tungsten (W) to titanium (Ti). Consisting of titanium oxide doped with 1-10%,
In addition, the photocatalytic functional layer constitutes an electrode for supplying a current to the ultraviolet light source. The photocatalytic functional layer is made of niobium titanium oxide or tantalum titanium oxide in which niobium (Nb) or tantalum (Ta) has a molar ratio of 3 to 10% with respect to titanium (Ti). The light source integrated photocatalyst device as described. 3. The light source integrated photocatalyst according to claim 1, wherein a layer made of another material does not exist between the photocatalytic functional layer and the group III nitride compound semiconductor layer which is a contact layer. apparatus. The ratio of the refractive index of the photocatalytic functional layer in contact with each other to the refractive index of the group III nitride compound semiconductor layer as the contact layer is 0.98 or more and 1.02 or less. 3. The light source integrated photocatalyst device according to 3. Between the photocatalytic functional layer and the group III nitride compound semiconductor layer which is a contact layer, there is only a translucent conductive layer made of another material and having a thickness of 100 nm or less. The light source integrated photocatalyst device according to claim 1 or 2. 6. The light source integrated photocatalyst device according to claim 1, wherein the photocatalytic functional layer is a p-electrode. The light source integrated photocatalyst device according to any one of claims 1 to 5, wherein the photocatalytic functional layer is an n-electrode. The light source integrated photocatalyst device according to any one of claims 1 to 7, further comprising a highly reflective layer on a side opposite to the photocatalytic functional layer with respect to a light emitting layer of the ultraviolet light source. . The photocatalytic functional layer comprises a double layer of the doped titanium oxide layer and a titanium oxide layer or a titanium oxynitride layer that is intentionally not doped with impurities. The light source integrated photocatalyst device according to any one of claims 1 to 8. The light source integrated photocatalyst device according to any one of claims 1 to 9, wherein the photocatalytic functional layer has irregularities on a surface thereof.

Images