JP2004277612A - Fluorescent material thin film and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent material thin film formed by doping a rare earth element ion as a light-emitting center into an Al<SB>2</SB>O<SB>3</SB>thin film as a mother crystal, that is excellent in controlling the composition and the concentration of the light-emitting center, and has a good color purity and a high brightness. <P>SOLUTION: This fluorescent material thin film comprises an Al<SB>2</SB>O<SB>3</SB>thin film as a mother crystal laminated on a heated substrate, and a CeO<SB>2</SB>thin film as a rare earth element oxide for a light-emitting center laminated thereon. It has a structure in which the light-emitting center is present as a component of a solid solution in the mother crystal of the Al<SB>2</SB>O<SB>3</SB>thin film. The Al<SB>2</SB>O<SB>3</SB>and CeO<SB>2</SB>thin films are formed by sputtering. The fluorescent material thin film prepared in an atmosphere of a gas mixture of argon and hydrogen emits a very strong blue light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is applied to a display device such as a thin film electroluminescence element and a field emission element, and is excellent in controlling the composition of a phosphor thin film and in controlling the concentration of a luminescent center, and has good color purity and high brightness. The present invention relates to a method for producing a thin film.
[0002]
[Prior art]
It is indispensable to color the phosphor for use in displays for personal computers, TVs and other displays. At present, ZnS: Sm and CaS: Eu are used as red light emitters, ZnS: Tb and CaS: Ce as green light emitters, and SrS: Ce and ZnS: Tm are used as blue light emitting phosphors. The phosphor thin films related to the three primary colors of red, green and blue have problems to be solved in light emission luminance, efficiency and color purity, and research is being continued (for example, see Patent Document 1).
[0003]
Many phosphors are obtained by adding a small amount of luminescent ions (activator) to a substance called a host crystal. Rare earth ions are often used as the activator ions. Until now, host crystals have been composed of oxides, sulfides, phosphates, halides, and the like composed of elements with the same ionic radius that can be replaced with rare earth ions.Many host crystals have complicated compositions and Has become. It is difficult to produce a high-quality phosphor thin film by controlling the chemical or physical properties of the multi-component host crystal and the luminescent center material.
For example, thiogallate- or thioaluminate-based blue phosphors such as SrGa ₂ S 4: Ce, CaGa ₂ O ₃ and BaAl ₂ S ₄ : Eu having significantly improved problematic blue color purity have been developed (for example, Patent Document 2).
[0004]
[Problems to be solved by the invention]
However, in order to make them thin, it is difficult to obtain a thin film having a uniform composition because of a multicomponent composition. Further, since the composition controllability is poor, the crystallinity is poor, or the occurrence of defects becomes a problem, and it has not been possible to form a phosphor thin film having practically high luminance yet.
In addition to pointing out these problems, an EL panel having a phosphor thin film with good color purity has been proposed (see, for example, Patent Document 3), but the host crystal has a multicomponent composition of alkaline earth sulfide, There is room for improvement in composition control.
Conventionally, rare earth ions to be added as activator ions are selected from those having the same ionic radius as those of the elements constituting the host crystal. There is no phosphor thin film in which a rare earth element is added to a host crystal as an oxide.
Furthermore, there has been no report on producing a phosphor thin film using Al ₂ O ₃ as a host crystal by vacuum evaporation, sputtering, laser evaporation, or the like, which is used for forming a normal phosphor thin film.
[0005]
[Patent Document 1]
JP-A-2003-31369 (front page, FIG. 2)
[Patent Document 2]
JP 08-134440 A (front page, FIG. 1)
[Patent Document 3]
JP-A-2003-45660 (front page, [0005])
[0006]
Therefore, the present invention solves such a problem, and uses a single element oxide having an ionic radius remarkably different from the rare earth ion to be added, particularly Al ₂ O ₃ as a host crystal, to control composition and emit light. It is an object of the present invention to provide a phosphor thin film having excellent center density control, good color purity, and high luminance, and a method for producing the phosphor thin film.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the phosphor thin film of the present invention is characterized in that a single element oxide thin film is compared with an ionic radius of an element constituting a single element oxide. A light-emitting thin film having a large ionic radius and a rare-earth element added to form a light-emitting center using a single-element oxide thin film as a host crystal.
In the invention according to claim 2, in addition to the above configuration, the light-emitting thin film contains one or more rare-earth elements, and can emit either monochromatic or multicolor light by activating light-emitting ions of the rare-earth elements. It is characterized by the following.
[0008]
The invention according to claim 3 is characterized in that the concentration of the rare earth element is based on the thickness ratio of the oxide thin film and the light emitting thin film.
The invention according to claim 4 is characterized in that non-luminescent ions which do not become the luminescent center among the rare earth elements are reduced to have luminescent ions which become the luminescent center.
The invention according to claim 5 is characterized in that the emission intensity is increased based on the emission center ion obtained by reducing the rare earth element ion.
The invention according to claim 6 is characterized in that it has a structure in which oxide thin films and light emitting thin films are alternately stacked.
The invention according to claim 7 is characterized in that it has a structure in which an oxide thin film and a light emitting thin film are mixed.
[0009]
The invention according to claim 8 is characterized in that it has a structure in which a light-emitting thin film is formed on a part of an oxide thin film, either a stacked layer or a mixed layer.
According to a ninth aspect of the present invention, there is provided a structure in which a light-emitting thin film is sequentially formed on a part of each oxide thin film in correspondence with a structure in which the oxide thin films are sequentially stacked, and the vertical direction of the stacked oxide thin film Is characterized by having a layer that partially emits light.
The invention according to claim 10 is characterized in that both the oxide thin film and the light emitting thin film are formed by sputtering.
An eleventh aspect of the present invention is characterized in that the oxide thin film is an Al ₂ O ₃ thin film, the light emitting thin film is a CeO ₂ thin film, and the Ce concentration with respect to Al ₂ O ₃ is equivalent to ₂ to 7 mol%. I do.
According to a twelfth aspect of the present invention, the oxide thin film is an Al ₂ O ₃ thin film, the light emitting thin film is a Eu ₂ O ₃ thin film, and the Eu concentration with respect to Al ₂ O ₃ corresponds to 0.5 to ₂ mol%. It is characterized by the following.
[0010]
The phosphor thin film having such a configuration has good color purity and high luminance.
[0011]
In the method for producing a phosphor thin film of the present invention, the invention according to claim 13 includes a first step of forming a single element oxide thin film on a heated substrate by sputtering, A second step of forming a light-emitting thin film to which a rare-earth element that forms a light-emitting center by using the thin film as a host crystal and forming a light-emitting center is formed by sputtering.
According to a fourteenth aspect of the present invention, in addition to the above configuration, the first step and the second step are alternately repeated to laminate the phosphor thin films.
The invention according to claim 15 is characterized in that the first step and the second step are simultaneously performed to form a mixed phosphor thin film.
[0012]
The invention according to claim 16 is characterized in that, in the second step, a light emitting thin film is formed on a part of the oxide thin film formed in the first step.
The invention according to claim 17 is that, as the target of the rare earth element which becomes the luminescence center in the second step, a target of the rare earth element itself, any one of a rare earth element oxide, a rare earth element sulfide and a rare earth element fluoride, or a combination thereof To form a light emitting thin film by sputtering.
The invention according to claim 18 is characterized in that in the second step, a plurality of targets of rare earth elements are simultaneously sputtered to activate a plurality of light-emitting ions, thereby forming a phosphor thin film which emits light in multiple colors.
The invention according to claim 19 is characterized in that either the first step or the second step, or both steps, are performed by sputtering under an inert gas atmosphere or a mixed gas atmosphere of an inert gas and hydrogen gas. It is characterized by forming a film.
[0013]
The invention according to claim 20 is characterized in that the single element oxide thin film formed in the first step is an Al ₂ O ₃ thin film, and the light emitting thin film formed in the second step is CeO _2. .
The invention of claim 21, wherein, in addition to the structure described above, _Al 2 _{O 3} thin film and CeO ₂ film thickness ratio of the thin film is characterized in that 7 to 30.
The invention according to claim 22 is that the single element oxide thin film formed in the first step is an Al ₂ O ₃ thin film, and the light emitting thin film formed in the second step is an Eu ₂ O ₃ thin film. Features.
According to a twenty- _{third aspect} of the present invention, in addition to the above configuration, the thickness ratio of the Al ₂ O ₃ thin film to the Eu ₂ O ₃ thin film is 25 to 120.
[0014]
In the method of manufacturing a phosphor thin film having such a configuration, since a rare earth element is added to the Al ₂ O ₃ thin film, which is a single oxide, the fluorescence is excellent in composition control, crystallinity, and excellent reproducibility. A body thin film can be formed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment according to the present invention will be described below with reference to FIGS.
A preferred embodiment according to the phosphor thin film of the present invention is a phosphor thin film in which a single element oxide, Al ₂ O ₃ , is used as a host crystal and a rare earth element is used as a luminescent center. A rare earth element whose ionic radius is significantly different from the ionic radius of the element is added.
[0016]
Al has a valence of trivalence, a coordination number of 6, and an ionic radius of 0.53 °. When a rare earth element is added, for example, Ce has a valence of 3, and a coordination number of 6, and has an ionic radius of 1.01 °. Tb has a valence of 3, and a coordination number of 6, and has an ionic radius of 1.01 °. Is 0.92Å, Eu is divalent, has a coordination number of 6, and has an ionic radius of 1.17, and Lu is trivalent, has a coordination number of 6, and has an ionic radius of 0.86Å. is there.
Therefore, the ionic radius of the added rare earth element is approximately twice as large as the ionic radius of Al constituting the host crystal. Here, in the present embodiment, a large difference means a difference of about twice.
[0017]
Phosphor thin film of the present embodiment is provided with Al ₂ O ₃ thin film is deposited as a host crystal onto the substrate, and a CeO ₂ thin film which is laminated as an oxide of a rare earth element as an emission center, Al ₂ O ₃ thin film It has a structure in which the luminescent center is dissolved in the host crystal. The Al ₂ O ₃ thin film and the CeO ₂ thin film are thin films produced by sputtering.
The substrate only needs to be able to withstand the temperature at which the thin film is formed and the temperature at which the rare-earth ions serving as the emission center are activated, and the heat-resistant temperature is desirably 800 ° C. or higher. For example, a quartz glass substrate, an alumina substrate, or the like is preferable.
[0018]
In order to add an appropriate amount and an appropriate amount of rare earth ions in the base crystal of the Al ₂ O ₃ thin film, the amount of each thin film deposited and the substrate temperature are determined. For example, when the rare earth ion is Ce, if the substrate temperature is set to 500 ° C. to 800 ° C., the luminescent centers are dissolved in the Al ₂ O ₃ thin film host crystal, and a phosphor thin film in which the luminescent centers are uniformly distributed can be obtained.
The _Al 2 _{O 3} thin film and CeO ₂ film thickness ratio of the thin film, uniform distribution of the luminescent ions, is determined from such emission _intensity, Al 2 _{O 3} thin film is preferably in the range of 50A～120A, CeO ₂ thin film at this time Is preferably 4 ° to 7 °.
Therefore, it is preferable that the Al ₂ O ₃ thin film and the CeO ₂ thin film are stacked in a thickness ratio of about 7 to 30. At this time, the Ce concentration with respect to Al ₂ O ₃ corresponds to about 2 to 7 mol%.
[0019]
The present embodiment is a phosphor thin film in which an Al ₂ O ₃ thin film having a thickness of 70 ° and a CeO ₂ thin film having a thickness of 4 ° are stacked on a heated substrate at 600 ° C.
FIG. 1 is a diagram showing an emission spectrum of the phosphor thin film according to the present embodiment, in which the vertical axis indicates the emission intensity (relative intensity), the horizontal axis indicates the emission wavelength, and (a) indicates the fluorescence produced in an argon gas atmosphere. (B) shows the emission spectrum of the phosphor thin film produced in a mixed gas atmosphere of argon gas and hydrogen gas.
Note that the embodiment corresponds to a diagram showing an emission spectrum in the example for convenience of explanation.
[0020]
Referring to FIG. 1A, a phosphor thin film formed in an atmosphere of an inert gas such as an argon gas emits blue light having an emission peak of about 460 nm corresponding to Ce ³⁺ with respect to excitation light of 360 nm.
Referring to FIG. 1 (b), the phosphor thin film formed in a mixed gas atmosphere of argon gas and hydrogen gas has a remarkably higher emission intensity than that of the phosphor thin film formed in an argon gas atmosphere. It emits blue light having an emission peak of about 450 nm and good color purity.
[0021]
By the way, in a sputtering gas atmosphere of a mixed gas of an argon gas and an oxygen gas, the atmosphere becomes an oxidizing atmosphere, and Ce ^4+, which is non-luminous, is added to the base crystal instead of Ce ³⁺ , which serves as a luminescent center. Not observed. However, an argon gas or a mixed gas of an argon gas and a hydrogen gas forms a reducing atmosphere, and can be activated by Ce ⁺ _{3. As} shown in FIG. 1, photoluminescence can be observed in the Al ₂ O ₃ : Ce phosphor thin film.
[0022]
This emission peak is about 450 nm as shown in FIG. 1B, and emits strong blue light even in daylight.
Generally, the better the crystallinity, the stronger the light emission. Therefore, it is conceivable to locally improve the crystallinity by introducing hydrogen gas. However, a reduction action is important to enter Ce ³⁺ from Ce ⁴⁺ into the parent crystal. It is considered that the ratio of entering Ce ³⁺ as a light-emitting ion increased due to the reduction effect of hydrogen. Therefore, in this embodiment, the phosphor thin film which can be activated so that non-light-emitting Ce ⁴⁺ becomes a luminescent center by being manufactured in a reducing atmosphere, and is activated as Ce ³⁺ which becomes light-emitting ions. Can be.
[0023]
Next, another embodiment will be described. This embodiment is a phosphor thin film in which an Al ₂ O ₃ thin film having a thickness of 70 ° and a Eu ₂ O ₃ thin film having a thickness of 2 ° are stacked on a substrate at 800 ° C.
The Al ₂ O ₃ thin film preferably has a range of 50 ° to 120 °, the luminescent ion concentration is lower than that of Ce, and the luminous intensity is high when the thickness of the Eu ₂ O ₃ thin film is 1 ° to ₂ °. Therefore, it is preferable that the thickness of the Al ₂ O ₃ thin film and the Eu ₂ O ₃ thin film is about 25 to 120. At this time, the Eu concentration with respect to Al ₂ O ₃ corresponds to about 0.5 to ₂ mol%.
[0024]
FIG. 2 shows an emission spectrum of an Al ₂ O ₃ : Eu phosphor thin film according to another embodiment prepared in an argon gas atmosphere, and (a) shows an emission spectrum corresponding to Eu ³⁺ ions with respect to excitation light of 254 nm. (B) shows the emission spectrum of Eu ²⁺ ions with respect to the excitation light of 365 nm. In another embodiment in an argon gas atmosphere, as shown in FIG. 2A, a linear emission spectrum in a red region of 610 nm to 630 nm due to a known ff transition centered on Eu ³⁺ ions, and FIG. As shown in b), a broad emission spectrum due to the df transition characteristic of Eu ²⁺ ions is observed. That is, this other embodiment is a phosphor thin film in which the emission centers of Eu ²⁺ ions and Eu ³⁺ ions are mixed.
[0025]
FIG. 3 shows an emission spectrum of an Al ₂ O ₃ : Eu phosphor thin film according to another embodiment prepared in a mixed gas atmosphere of argon and hydrogen, and (a) corresponds to Eu ³⁺ ions with respect to excitation light of 254 nm. (B) shows the emission spectrum of Eu ²⁺ ion with respect to the excitation light of 365 nm. As shown in FIG. 3, the emission spectrum corresponding to Eu ³⁺ is small, the emission spectrum due to the emission center of Eu ²⁺ is mainly, and the emission intensity is large.
Therefore, in the phosphor thin film produced in a mixed gas atmosphere of argon and hydrogen, most of the luminescence centers of Eu ³⁺ are activated by the host crystal as luminescence centers of Eu ²⁺ due to the effect of hydrogen reduction.
[0026]
In the above-described embodiment, an example of a fluorescent thin film obtained by activating Ce and Eu on Al ₂ O ₃ has been described. However, 12 kinds of trivalent rare earth elements (Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) may be used as the phosphor thin film.
[0027]
In addition, although a phosphor thin film having a structure in which an Al ₂ O ₃ thin film serving as a host crystal and a thin film forming an emission center are stacked has been described as an example, a structure in which these thin films are alternately stacked may be employed. Alternatively, the structure may be a mixed layer.
Further, the thin film forming the emission center may have a structure having different types of emission center ions. At this time, the thin film may be formed as a stacked layer or a mixed layer.
The phosphor thin film having such a configuration can emit light in multiple colors by activating a plurality of light-emitting ions.
[0028]
Further by increasing the thickness of the Al ₂ O ₃ as a host crystal, and locally emission ions are added structure only part of the laminated film, and a thin film to form Al ₂ O ₃ thin film as an emission center A phosphor thin film having a layered structure obtained by repeating the above may be used. In the phosphor thin film having such a configuration, since a layer partially emits light in a vertical plane of the phosphor thin film, light can be partially emitted in the vertical plane.
[0029]
Next, a method for manufacturing a phosphor thin film will be described.
In a preferred embodiment of the method for producing a phosphor thin film according to the present invention, a magnetron sputtering apparatus that is frequently used for forming a thin film of an inorganic oxide is preferably used as a film forming apparatus. FIG. 4 is a conceptual diagram of a main part configuration of a magnetron sputtering apparatus. Referring to FIG. 4, magnetron sputtering apparatus 10 includes an Al ₂ O ₃ target 11 serving as a base crystal thin film, a rare earth element oxide target 12 serving as a luminescence center ion, and a target 11, 12 driven and rotated. A heating substrate 15 disposed directly above, and shutters 13 and 14 on each of the targets 11 and 12 for controlling deposition of sputter particles from each of the targets 11 and 12; High-frequency power is independently applied to 11 and 12, and binary simultaneous discharge is enabled. In the example shown in FIG. 4, only two sets of targets and shutters are shown, but these may be two or more as appropriate.
[0030]
In place of the target of the rare earth element oxide serving as the emission center ion, a target of a rare earth element itself, a target of a rare earth element sulfide, or a compound target of a rare earth element fluoride may be used.
[0031]
In such a magnetron sputtering apparatus 10, when the heated substrate 15 comes on the Al ₂ O ₃ target 11, the shutter 13 is opened, and the sputtered particles of the Al ₂ O ₃ target 11 are deposited on the heated substrate 15 by the applied power and time. accumulate.
Next, the heating substrate 15 moves onto the target 12 of an oxide of a rare earth element such as CeO ₂ or Eu ₂ O _3, and sputtered particles of the oxide of the rare earth element are deposited on the heating substrate 15 depending on the applied power and time. .
[0032]
This operation is repeated to form a phosphor thin film by laminating thin films. In this example, sputter particles from each target are deposited under the control of the shutter. However, by using the dual simultaneous sputtering method, the Al ₂ O ₃ thin film, which is the host crystal, and the emission center ions are formed. It is also possible to form a rare earth element simultaneously in a laminated or mixed layer form. Even when this mixed layer is formed, composition control and uniform addition of the luminescent center are extremely good.
[0033]
Further, it is also possible to form a thin film of a rare earth element oxide serving as a luminescence center ion on a part of the Al ₂ O ₃ thin film by shutter control.
In addition, in the layer formation using two targets, the thickness of the Al ₂ O ₃ thin film serving as a host crystal is increased, and only a part of the layered film is made to have a structure in which luminescence center ions are added. A layered structure in which a ₂ O ₃ thin film and a phosphor thin film are repeated can be formed, and a layered phosphor thin film that emits light partially in a vertical plane of the thin film can be formed. Note that a sputtering gas can be introduced from each of gas lines of argon (Ar), hydrogen (H ₂ ), and oxygen (O ₂ ), and a thin film can be formed by changing a mixing ratio.
[0034]
Controlling the deposition amount of each layer and substrate temperature are important factors in order to activate and add a proper amount of rare earth element ions into the host crystal. By using a binary target and, if necessary, two or more targets, each target can be controlled independently, so that the deposition amount of each layer can be freely set and a plurality of emission center ions can be added. If the temperature is set to a specific substrate temperature, the luminescent center is dissolved in the Al ₂ O ₃ host crystal, and a uniformly distributed phosphor thin film can be obtained.
[0035]
In such a method for producing a phosphor thin film, since a combination of a single element oxide and a rare earth element is used, the composition control in the thin film formation compared to the conventional phosphor thin film using a complex compound as a host crystal. It is excellent in controlling the concentration of the light emission center and the like.
Therefore, in the method for producing a phosphor thin film according to the present invention, a thin film having a uniform composition can be obtained, and a highly viable phosphor thin film having good crystallinity can be produced.
[0036]
【Example】
Next, examples will be described. First, a first embodiment will be described.
As a first embodiment, a case where CeO ₂ is used as a target of a rare earth oxide will be described.
In an Ar gas atmosphere at a substrate temperature of 600 ° C. and 0.5 Pa, Al ₂ O ₃ was stacked at a thickness of 70 ° and CeO ₂ at a thickness of 4 °. With this laminated film, a blue fluorescent thin film having an emission peak of about 460 nm corresponding to Ce ³⁺ with respect to the excitation light of 360 nm can be formed as shown in the emission spectrum (PL: photoluminescence) by the light excitation of FIG. Was.
In the present manufacturing conditions, the temperature is in the range of 200 ° C to 800 ° C. PL was observed from a temperature of 300 ° C. or higher, but preferably 500 ° C. or higher. The temperature was the temperature during film formation, and no other heat treatment was performed. At the time of growth, a phosphor thin film is formed.
[0037]
Although the thickness of each layer of Al ₂ O ₃ was observed to be PL even though it was quite thick (up to 1500 °), the range of 50 ° to 120 ° was preferable from the viewpoint of the uniform distribution of luminescent ions or luminous intensity. Similarly, a high emission center concentration can be realized for the luminescent ions, but from the viewpoint of uniform distribution and luminous intensity, the thickness is preferably 4 to 7 mm. Therefore, by stacking thin films formed with a thickness ratio of Al ₂ O ₃ and CeO ₂ of about 7 to 30 (corresponding to a Ce concentration of about 2 to 7 mol% with respect to Al ₂ O ₃ ), a high-luminance blue Can be prepared.
[0038]
In a sputtering gas atmosphere formed by a mixture of Ar and oxygen (O ₂ ) gas, an oxidizing atmosphere is formed, and Ce ⁴⁺ which becomes non-luminous instead of Ce ³⁺ which becomes a luminescence center is added to the host crystal, so PL is observed in the formed thin film. Was not done.
Ar and a mixed gas of Ar and H ₂ resulted in a reducing atmosphere, which could be activated by Ce ³⁺ , and PL was observed in the Al ₂ O ₃ : Ce thin film.
In particular, the Al ₂ O ₃ : Ce thin film produced with a mixed gas of Ar and H ₂ has a curve (b) in FIG. 1 which is different from the PL intensity of the thin film formed in an Ar gas atmosphere shown in the curve (a) in FIG. As shown, the PL intensity was remarkably large. In addition, a blue fluorescent thin film having an emission peak of about 450 nm and good color purity was obtained.
When the crystallinity of this phosphor thin film was examined by X-ray diffraction, it was found to be amorphous. The Al ₂ O ₃ : Ce thin film obtained in this example shows an intense blue emission as it can be confirmed even in daylight while being amorphous.
[0039]
Next, a case where Eu ₂ O ₃ is used as a rare-earth oxide target will be described as a second embodiment. FIG. 2 shows an example of an emission spectrum of an Al ₂ O ₃ : Eu thin film laminated at a substrate temperature of 800 ° C., Al ₂ O ₃ at 70 ° and Eu ₂ O ₃ at 2 ° in an Ar gas atmosphere of 0.5 Pa. In this case, a linear emission spectrum in the red region of 610 to 630 nm due to the known ff transition with the Eu ³⁺ ion as the emission center and a broad emission spectrum due to the df transition specific to Eu ²⁺ were observed. That is, a phosphor thin film in which the emission centers of Eu ²⁺ ions and Eu ³⁺ ions were mixed was formed.
[0040]
The experiment was performed at a temperature in the range of 200 ° C. to 800 ° C. in the film forming conditions. Although light emission was confirmed from a temperature of 300 ° C. or higher as in the first embodiment, it is preferably 500 ° C. or higher. The thickness of Al ₂ O ₃ of the host crystal is preferably in the range of 50 ° to 120 ° as in the first embodiment, and the luminous ion concentration is 1 ° to ₂ ° in terms of Eu ₂ O ₃ film thickness, which is smaller than that of Ce. When the film was formed, the result was that the emission intensity was large. Therefore, in terms of the film thickness ratio of Al ₂ O ₃ and Eu ₂ O _3, a good result was obtained at about 25 to 120 (the Eu concentration with respect to Al ₂ O ₃ was equivalent to about 0.5 to ₂ mol%).
[0041]
When the crystallinity of this phosphor thin film was examined by an X-ray diffraction method, it was in an amorphous state as in the first embodiment. Further, the film formed in the mixed gas atmosphere of Ar and H ₂ has the effect of the hydrogen reducing action similarly to the first embodiment, and most of the luminescence center of Eu ³⁺ is activated by the luminescence center of Eu ²⁺ to the host crystal. Was done.
FIG. 3 shows an emission spectrum of a thin film manufactured with a flow ratio of Ar: H ₂ of 3: 1. The curve (a) in FIG. 3 shows the emission spectrum observed with the excitation light of 254 nm, and the curve (b) in FIG. 3 shows the emission spectrum observed with the excitation light of 365 nm. The emission spectrum corresponding to Eu ³⁺ was small for any of the excitation lights, the emission spectrum based on the emission center of Eu ²⁺ was dominant, and the emission intensity was high. As in the first embodiment, also in the second embodiment, by mixing and sputtering Ar and H ₂ gas, it is possible to improve the quality of a phosphor thin film having Al ₂ O ₃ as a mother crystal and a rare earth element as a luminescent center. Was confirmed.
[0042]
【The invention's effect】
As can be understood from the above description, the phosphor thin film of the present invention has the effects of good color purity and high luminance.
Further, since the method for producing a phosphor thin film according to the present invention is a method in which a rare earth element is added to an Al ₂ O ₃ thin film that is a single oxide, a thin film having excellent composition control, good crystallinity, and excellent reproducibility can be obtained. It has the effect that it can be formed.
Therefore, a phosphor thin film using an Al ₂ O ₃ thin film as a host crystal, which has not been considered conventionally, can be produced, and a wide range of applications can be produced as a phosphor thin film used for a display device.
[Brief description of the drawings]
FIG. 1 is a diagram showing an emission spectrum of a phosphor thin film according to the present embodiment.
FIG. 2 shows an emission spectrum of an Al ₂ O ₃ : Eu thin film according to another embodiment manufactured in an argon gas atmosphere.
FIG. 3 shows an emission spectrum by photoexcitation of an Al ₂ O ₃ : Eu phosphor thin film according to another embodiment produced in a mixed gas atmosphere of argon and hydrogen.
FIG. 4 is a conceptual diagram of a main part configuration of a magnetron sputtering apparatus.
[Explanation of symbols]
Reference Signs List 10 magnetron sputtering apparatus 11, 12 target 13, 14 shutter 15 heated substrate

Claims (23)

A single-element oxide thin film has an ionic radius larger than the ionic radius of the element constituting the single-element oxide, and the single-element oxide thin film is used as a host crystal to form an emission center. A phosphor thin film comprising a light emitting thin film to which a rare earth element is added. 2. The light-emitting thin film according to claim 1, wherein the light-emitting thin film contains one or more rare-earth elements, and can emit either monochromatic or multicolor light by activating light-emitting ions of the rare-earth elements. 3. Phosphor thin film. The phosphor thin film according to claim 1, wherein the phosphor thin film has an addition concentration of a rare earth element based on a thickness ratio of the oxide thin film and the light emitting thin film. The phosphor thin film according to any one of claims 1 to 3, further comprising a light-emitting ion that becomes a light-emitting center by reducing non-light-emitting ions that do not become a light-emitting center among the rare earth elements. The phosphor thin film according to any one of claims 1 to 3, wherein a light emission intensity is increased based on a light emission center ion obtained by reducing the rare earth element ion. The phosphor thin film according to any one of claims 1 to 5, wherein the phosphor thin film has a structure in which the oxide thin film and the light emitting thin film are alternately stacked. The phosphor thin film according to any one of claims 1 to 5, wherein the phosphor thin film has a structure in which the oxide thin film and the light emitting thin film are mixed. The phosphor thin film according to any one of claims 1 to 7, wherein the phosphor thin film has a structure in which one of the light emitting thin film is laminated and a mixed layer is formed on a part of the oxide thin film. Corresponding to the structure in which the oxide thin films are sequentially stacked, the light emitting thin film is sequentially formed on a part of each oxide thin film, and light is partially emitted in a vertical plane of the stacked oxide thin films. The phosphor thin film according to claim 1, further comprising a layer. The phosphor thin film according to any one of claims 1 to 9, wherein both the oxide thin film and the light emitting thin film are formed by sputtering. Wherein an oxide thin film _Al 2 _{O 3} thin film, the light-emitting thin film is a CeO ₂ film, Ce concentration with respect to _Al 2 _{O 3} is equal to or equivalent to 2～7Mol%, claims 1 to 10 The phosphor thin film according to any one of the above. The oxide thin film is a _Al 2 _{O 3} thin film, the light-emitting thin film is an _Eu 2 _{O 3} thin film, Eu concentration against _Al 2 _{O 3} is equal to or equivalent to 0.5 to 2 mol%, wherein Item 11. The phosphor thin film according to any one of Items 1 to 10. A first step of forming a single-element oxide thin film on a heated substrate by sputtering, and a step of forming a light-emitting thin film to which a rare-earth element that forms a luminescence center using the single-element oxide thin film as a host crystal by sputtering; And a second step of forming a film. 14. The method according to claim 13, wherein the first step and the second step are alternately repeated to form a laminated phosphor thin film. 15. The method for producing a phosphor thin film according to claim 13, wherein the first step and the second step are performed simultaneously to form a mixed phosphor thin film. 17. The method according to claim 13, wherein the light emitting thin film is formed on a part of the oxide thin film formed in the first step in the second step. In the second step, as the target of the rare earth element serving as the emission center in the second step, a target of the rare earth element itself, a rare earth element oxide, a rare earth element sulfide and a rare earth element fluoride, or a combination thereof is sputtered to form a light emitting thin film. The method for producing a phosphor thin film according to claim 13, wherein the phosphor thin film is formed. 18. The phosphor thin film according to claim 13, wherein a plurality of targets of rare earth elements are simultaneously sputtered in the second step to activate a plurality of light-emitting ions to form a phosphor thin film that emits light in multiple colors. A method for producing a phosphor thin film according to any one of the above. Either the first step or the second step, or both steps, are formed by sputtering under an inert gas atmosphere or a mixed gas atmosphere of an inert gas and a hydrogen gas. The method for producing a phosphor thin film according to any one of claims 13 to 18. Oxide thin film of a single element of depositing in said first step is Al ₂ O ₃ thin film, the light-emitting thin film to be formed in the second step of claim 13 to 19, characterized in that the CeO ₂ A method for producing a phosphor thin film according to any one of the above. Characterized in that the _Al 2 _{O 3} thin film with a thickness ratio of the CeO ₂ thin film is 7 to 30, a method for manufacturing a phosphor thin film according to claim 20. The oxide thin film of a single element formed in the first step is an Al ₂ O ₃ thin film, and the light emitting thin film formed in the second step is a Eu ₂ O ₃ thin film. 21. The method for producing a phosphor thin film according to any one of 13 to 20. The method for manufacturing a phosphor thin film according to claim 22, wherein the _Al 2 _{O 3} thin film and the _Eu 2 _{O 3} ratio of the thickness of the thin film is characterized by a 25 to 120.

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