JP5706074B2 - Variable temperature optical sensor element - Google Patents

Description

  The present invention relates to a temperature-variable optical sensor element provided with a light emitting means containing zinc oxide or heat-treated zinc oxide.

  Zinc oxide is usually a white powder, but a high-purity one is transparent and conductive, and can be used as a material for a transparent electrode. On the other hand, it has a property as a wide band gap semiconductor having a band gap of about 3.37 eV. And since it has low toxicity and is easily available, it is also widely used as a raw material for white pigments, UV blocking cosmetics, pharmaceuticals, and the like.

  On the other hand, nanoparticles having a crystal size reduced to the nanometer level have the property of emitting light in the visible region due to the quantum size effect, and are expected to be applied as light emitting elements. Accordingly, various attempts have also been made to apply nanoparticles to light-emitting elements with respect to zinc oxide (see, for example, Patent Document 1). The development is expected to become even more important.

JP 2009-87756 A

  However, it cannot be said that the light-emitting element including zinc oxide has been sufficiently studied for the characteristics as an optical element so far, and there is still much room for investigation as to the possibility as an optical element. Is the actual situation.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the optical element which has a novel function provided with the zinc oxide.

To solve the above problem,
The first invention of the present invention includes: a light emitting means for containing a pressurized heat-treated zinc oxide, and temperature control means for adjusting the temperature of the light emitting means, a pumping means for irradiating excitation light to the light emitting means, the light emitting And a temperature-variable optical sensor element configured separately or as a single body, wherein the light-emitting means emits light differently depending on the temperature during excitation light irradiation. A spectrum of the emission spectrum obtained by measuring the emission spectrum when the excitation means is irradiated by the excitation means to the light emission means whose temperature is adjusted by the temperature control means, Provided is a temperature variable optical sensor element characterized in that information specific to a substrate holding a light emitting means is obtained from a combination of a pattern, peak intensity or valley intensity.
The second aspect of the present invention includes: a light emitting means for containing a pressurized heat-treated zinc oxide, and temperature control means for adjusting the temperature of the light emitting means, a pumping means for irradiating excitation light to the light emitting means, And a temperature-variable optical sensor element configured separately or as a single body, wherein the light emission means has a light emission intensity at the time of excitation light irradiation. The temperature increases as the temperature rises, and is obtained by measuring the emission intensity when the excitation means is irradiated with the excitation light by the excitation means on the light emission means whose temperature is adjusted by the temperature adjustment means. Provided is a temperature variable optical sensor element characterized in that information specific to a substrate holding a light emitting means is acquired from a combination of a peak pattern, peak intensity or valley intensity in an emission spectrum.
In the temperature variable optical sensor element of the present invention, it is preferable that the peak position in the emission spectrum shifts depending on the temperature at the time of excitation light irradiation.
The temperature-variable optical sensor element of the present invention preferably contains zinc oxide that has been heat-treated in the presence of an inert gas or ammonia gas.
In the temperature variable optical sensor element of the present invention, it is preferable that the light emitting means further contains gallium nitride or titanium dioxide.
In the variable temperature optical sensor element of the present invention, as the light emitting means, the zinc oxide or the heat-treated zinc oxide is dispersed in water or a water-soluble liquid, or the dispersion is applied and dried. It is preferable to provide the layer formed.

  According to the present invention, an optical element having a novel function including zinc oxide can be obtained.

It is a figure which shows the measurement data about the ZnO powder in Example 1, (a) is the imaging data of a SEM image, (b) is an X-ray diffraction pattern. It is a graph which shows the relationship between the wavelength of the detection peak in the emission spectrum of the ZnO powder of Example 1, and the temperature at the time of measurement. It is a figure which shows the measurement data about the GaN powder in the reference example 1, (a) is the imaging data of a SEM image, (b) is an X-ray diffraction pattern. 4 is a graph showing the relationship between the emission intensity of GaN powder and the temperature at the time of measurement in Reference Example 1. 6 is a graph showing a measurement result of an emission spectrum of GaN powder in Reference Example 2. It is a figure which shows the measurement data about the ZnO powder in Example 2, (a) shows the measurement result of the emission spectrum for every temperature at the time of measurement, (b) shows the relationship between the wavelength of a peak and the temperature at the time of measurement, respectively. It is a graph. 6 is a graph showing a measurement result of an emission spectrum of NH ₃ heat-treated GaN-ZnO powder in Example 3. An imaging data of an SEM image of the NH ₃ heat-treated _TiO 2 -ZnO powder in Example 4, (a) 300 ℃ heat treatment temperature is, (b) the heat treatment temperature is 400 ℃, (c) heating This is image data when the processing temperature is 500 ° C. Example is a graph showing the measurement results of the emission spectrum of the NH ₃ heat-treated _TiO 2 -ZnO powder in 4, (a) heat treatment temperature is 300 ° C. is, (b) the heat treatment temperature is 400 ° C., (c ) Is a graph showing the measurement results of the emission spectrum when the heat treatment temperature is 500 ° C. Example is a graph showing the measurement results of the emission spectrum of _{N 2} precooked _TiO 2 -ZnO powder in 5, (a) heat treatment temperature is 300 ° C. is, (b) the heat treatment temperature is 400 ° C., (c ) Is a graph showing the measurement results of the emission spectrum when the heat treatment temperature is 500 ° C. It is a top view of the two-dimensional code printed with the ink in Examples 6-7. It is a graph which shows the measurement result of the emission spectrum at the time of the temperature at the time of measurement in Examples 6-7 at the time of 25 degreeC at the time of ink 1-4 use. Is a graph showing the measurement results of the emission spectrum in the case of using TiO ₂ -ZnO-containing ink of Example 6, (a) ink 1, the (b) is a graph when the ink 2. It is a graph which shows the measurement result of the emission spectrum at the time of using the ZnO containing ink of Example 7, (a) is the graph in the case of the ink 3, (b) is the graph in the case of the ink 4. FIG. 10 is a graph showing an emission spectrum measurement result of N ₂ heat-treated TiO ₂ —ZnO powder in Example 8. 10 is a graph showing an emission spectrum measurement result of NH ₃ heat-treated ZnO powder in Example 6. It is a graph which shows the measurement result of the emission spectrum at the time of using the ink 2 in Example 10. FIG. 10 is a graph showing the measurement results of the emission spectrum when ink 4 in Example 11 is used.

The temperature variable optical sensor element of the present invention includes a light emitting means containing at least zinc oxide or heat-treated zinc oxide, a temperature adjusting means for adjusting the temperature of the light emitting means, and an excitation for irradiating the light emitting means with excitation light. And the light emitting means exhibits a different emission spectrum depending on the temperature at the time of excitation light irradiation.
The temperature variable optical sensor element of the present invention includes a light emitting means containing at least zinc oxide or heat-treated zinc oxide, a temperature adjusting means for adjusting the temperature of the light emitting means, and irradiating the light emitting means with excitation light. And a light emitting intensity of the light emitting means increases with an increase in temperature during excitation light irradiation.
In the present invention, the emission spectrum of zinc oxide (hereinafter abbreviated as ZnO) changes depending on the temperature at the time of excitation light irradiation, or the emission intensity increases as the temperature at the time of excitation light irradiation increases. This is used as a temperature variable optical sensor element.

  For example, ZnO may be one usually used in the semiconductor field, and preferably has a purity of 99.9% or more, more preferably 99.99% or more. The zinc oxide crystal size (average particle size) is preferably 3 μm or less, and more preferably 2 μm or less. Nanoparticles smaller than 1 μm may be used.

ZnO may be heat-treated. In this case, zinc oxide heat-treated in the presence of an inert gas or ammonia gas is preferred. The inert gas may be a commonly used gas, preferably a rare gas such as argon (Ar) gas or nitrogen (N ₂ ) gas, and more preferably N ₂ gas.
The temperature during the heat treatment may be appropriately selected according to the purpose, but is preferably 150 to 650 ° C, and more preferably 250 to 550 ° C. By setting it as such a range, the change of the emission spectrum depending on the temperature at the time of excitation light irradiation becomes clearer.
The time during the heat treatment of ZnO may be appropriately adjusted according to the temperature. For example, when the heating temperature is within the above range, it may be usually about 0.5 to 2 hours.

For example, when the heat treatment of ZnO under NH ₃ gas coexist, is H (hydrogen) activation of the NH ₃ gas, thereby believed O in ZnO (oxygen) is reduced. A particularly preferable heat treatment temperature at this time is 450 to 550 ° C.
Thus, it is considered that the heat treatment of ZnO in the presence of a highly active gas can change the amount of O (oxygen) vacancy defects and change the emission spectrum more clearly. .

As a light emitting means, in addition to ZnO, a material further containing gallium nitride (hereinafter abbreviated as GaN) or titanium dioxide (hereinafter abbreviated as TiO ₂ ) can be exemplified as a preferable one.
In this case, GaN may be one normally used in the semiconductor field, and preferably has a purity of 99.9% or more. As TiO ₂ , for example, a commercially available product can be used.

When ZnO and GaN are used in combination, “the number of moles of ZnO: the number of moles of GaN” is preferably 7: 3 to 3: 7, and more preferably 6: 4 to 4: 6.
When ZnO and TiO ₂ are used in combination, “the number of moles of ZnO: the number of moles of TiO ₂ ” is preferably 7: 3 to 3: 7, and preferably 6: 4 to 4: 6. More preferred.
For example, even when GaN or TiO ₂ is used in combination with ZnO, it is considered that when ZnO is heat-treated in the presence of NH ₃ gas, O (oxygen) in ZnO is reduced as described above.

In the present invention, the light emitting means may contain other components in addition to the ZnO, GaN, and TiO ₂ within a range not impeding the effects of the present invention. Other components may be appropriately selected according to the purpose.

  What is necessary is just to adjust suitably the temperature of the light emission means at the time of excitation light irradiation according to the structure and objective of a light emission means. Usually, it is preferably 15 to 120 ° C, more preferably 20 to 100 ° C. By setting it as such a range, the change of the emission spectrum and emitted light intensity for every temperature becomes clearer.

The light emitting means is not particularly limited as long as the temperature can be arbitrarily adjusted according to the purpose. For example, ZnO, if necessary, GaN, TiO ₂ , and other components (hereinafter collectively referred to as ZnO or the like) may be in a powder state, or ZnO or the like is dispersed in the dispersion. It may be in a state of being made, or may be in a state in which a part or all of ZnO or the like is dissolved in the solution. Further, a layer in which ZnO or the like is contained in a layer formed by applying and drying the dispersion or solution may be used.

  The liquid component of the dispersion or solution is preferably water or a water-soluble liquid. The water-soluble liquid is preferably alcohol, and more preferably ethanol.

  By forming a layer formed by applying and drying the dispersion or solution on a substrate, the handleability of the element of the present invention can be further improved, and the application can be greatly expanded. For example, the dispersion or solution may further contain a dye, pigment, binder or the like to form an ink, which can be used to form characters or patterns.

  The material of the base material to which the dispersion or solution is applied can be arbitrarily selected according to the purpose, and may be selected from known materials such as various resins, metals, alloys, papers, and woods. In addition, the shape of the substrate can be arbitrarily selected according to the purpose, and may be any of a plate shape, a block shape, a spherical shape, a rod shape, or a composite shape in which two or more of these shapes are combined, and further limited thereto. Is not to be done.

In addition, when the ink is used, as the other components in the ink, in addition to those listed above, resins, colorants, fillers, solvents, various stabilizers, and the like can be given. The kind is not limited and can be used as it is if it is used in a conventional ink composition.
As the resin, for example, any of thermosetting resin, thermoplastic resin, electron beam curable resin, and ultraviolet curable resin can be used. For example, acrylic resin, polyamide resin, vinyl chloride-vinyl acetate copolymer, polyvinyl Butyral, nitrocellulose, cellulose acetate, urethane resin, polycarbonate, cyclized rubber, chlorinated rubber, chlorinated polyolefin resin, melamine resin, urea resin, urea-melamine resin, epoxy resin, alkyd resin, amino alkyd resin, A rosin-modified maleic resin or the like can be used alone or in combination.
As the colorant, various dyes and pigments can be used. As additives, waxes, plasticizers, leveling agents, surfactants, dispersants, antifoaming agents, chelating agents and the like can be used.
The content of ZnO or the like in the ink is 0.005 to 10% by mass with respect to the total solid content in the ink, and if it is less than 0.005% by mass, the emission intensity is too low and the detection becomes difficult. When it exceeds 10 mass%, printability will worsen.
The ink is preferably transparent and more preferably colorless and transparent. However, depending on the amount of ZnO or the like, it may become slightly cloudy.

  The temperature adjusting means for adjusting the temperature of the light emitting means is not particularly limited and may be a normally used heater or the like. Examples of the heater include those having a Peltier element as being excellent in handleability and versatility, but are not limited thereto.

  The excitation means for irradiating the light emitting means with excitation light can be arbitrarily selected from known ones such as a laser light source according to the purpose.

  The light emitting means shows a different emission spectrum depending on the temperature upon irradiation with excitation light by selecting appropriate conditions. That is, the spectrum of photoluminescence (hereinafter abbreviated as PL) shows temperature dependence. Here, “the emission spectra are different” means that “one or more of a change in peak pattern and a shift in peak position (wavelength) occur”. This is due to the temperature dependence of the emission spectrum when irradiated with excitation light such as ZnO contained in the light emitting means. Further, even different emission spectra are shown depending on the state of the heat treatment such as ZnO or the difference in the state based on the method.

For example, when ZnO is used alone and when it is used in combination with GaN or TiO ₂ , different emission spectra may be exhibited even if the conditions at the time of excitation light irradiation are the same regardless of the presence or absence of heat treatment.
In any of the above cases, if the conditions such as the temperature during the heat treatment are different, even if the temperature during the excitation light irradiation is the same, a different emission spectrum may be exhibited. And about a specific peak, intensity | strength can be enlarged with the rise in temperature at the time of excitation light irradiation. In the light-emitting elements known so far, the emission intensity decreases as the temperature increases during excitation light irradiation, and the light is extinguished so that the above knowledge is novel.
Further, in any of the above cases, the wavelength may be shifted or the intensity may be changed by a specific peak among a plurality of peaks in the emission spectrum.
Thus, the present invention makes the light emitting means function as a temperature variable optical sensor by utilizing the temperature dependence of the emission spectrum.

In the present invention, the light emitting means and the temperature adjusting means may be configured integrally, for example, or may be configured by appropriately combining those separately configured. Preferable examples include those in which the light emitting means is held on the base material and the base material is arranged in the vicinity with or without contact with the temperature control means.
A preferable example in which the light emitting means is held on the substrate is a material in which characters or patterns are formed on the substrate with a dispersion or solution containing ZnO or the like, preferably an ink. Such a thing is suitable as a memory element to which information peculiar to a substrate is given.

  It is preferable that the temperature variable optical sensor element of the present invention further includes a detecting unit that detects an emission spectrum of the light emitting unit. The detection means may be a known one, and examples thereof include, but are not limited to, those provided with means for detecting a light signal such as a CCD camera and means for analyzing the spectrum of the detected light signal. It is not a thing.

  The present invention can be applied to a device for optical communication by utilizing the function of the light emitting means as a light emitting element. Furthermore, not only that, for example, by detecting the emission spectrum of the light emitting means at a plurality of different temperatures, a plurality of types of emission spectra are obtained, and from combinations of peak patterns, peak intensities or valley intensities in these emission spectra. Since information peculiar to the substrate can be obtained with high accuracy, it is particularly suitable as an information identification sensor.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.

[Example 1]
<Measurement of emission spectrum of ZnO powder (1)>
About ZnO powder (the high purity chemical company make, purity 99.999%), the SEM image was imaged using the scanning electron microscope (SEM), and also X-ray diffraction (XRD) measurement was performed. The results are shown in FIG. In FIG. 1, (a) is imaging data, and (b) is an X-ray diffraction pattern.

Next, a heater was used as a temperature control means, and the emission spectrum was measured by irradiating the powder with laser while changing the temperature of the ZnO powder. The measurement was performed using a He—Cd laser (wavelength: 325 nm), a laser spot having a diameter of 1 mm, and a charge coupled device (CCD) as detection means. As a result, a peak was observed near the wavelength of 390 nm, and the wavelength shifted depending on the temperature at the time of measurement. FIG. 2 shows the relationship between the wavelength of the detected peak and the temperature at the time of measurement.
As is clear from FIG. 2, it was confirmed that the peak near the wavelength of 390 nm shifted to the longer wavelength side as the measurement temperature increased.

[Reference Example 1]
<Measurement of emission spectrum of GaN powder (1)>
About GaN powder (the high purity chemical company make, purity 99.99%), the SEM image was imaged using the scanning electron microscope (SEM), and also X-ray diffraction (XRD) measurement was performed. The results are shown in FIG. In FIG. 3, (a) is imaging data, and (b) is an X-ray diffraction pattern. Since GaN powder was separately prepared (prepared) by heat-treating Ga ₂ O ₃ (purity 99.99%) in an NH ₃ atmosphere at 850 ° C., the X-ray diffraction pattern was also measured for this. FIG. 3B is also shown.
As apparent from FIG. 3B, the separately prepared GaN powder showed the same diffraction pattern as that of the commercially available product, so that it was confirmed that the quality was the same as that of the commercially available product. Both diffraction patterns have different intensities, but this is based on the difference in the amount of powder used for measurement.

Next, the emission spectrum was measured in the same manner as in Example 1 except that GaN powder was used instead of ZnO powder. FIG. 4 shows the relationship between the emission intensity at this time and the temperature at the time of measurement.
As shown in FIG. 4, the emission intensity has a region that increases and a region that decreases as the measurement temperature increases. From the emission spectrum, peaks were observed near wavelengths of 390 nm and 670 nm. The intensity of the peak around the wavelength of 390 nm decreased with increasing measurement temperature. This is considered to be due to an increase in the probability of electrons trapped in the defect level as the temperature increases. On the other hand, the peak observed in the vicinity of the wavelength of 670 nm is considered to be due to defects.

  From FIG. 1A and FIG. 3A, it was confirmed that the size of the ZnO powder particles was 1 μm or less and the size of the GaN powder particles was about 5 μm. In addition, while the crystal form of ZnO powder is hexagonal, the crystal form of GaN powder is not the hexagonal crystal generally referred to, and it can be confirmed that ZnO powder has better crystallinity. It was. From FIG. 1 (b) and FIG. 3 (b), the half width of the peak in the X-ray diffraction pattern is narrower in the ZnO powder than in the GaN powder. Therefore, the ZnO powder has better crystallinity. It is clear.

[Reference Example 2]
<Measurement of emission spectrum of GaN powder (2)>
A carbon tape having a size of 5 mm × 5 mm was applied to the sample holder, and GaN powder (manufactured by Kojundo Chemical Co., Ltd., purity 99.99%) was applied thereto. Then, a heater is used as a temperature control means, and the temperature of the GaN powder is adjusted to 8 types of 25 ° C., 30 ° C., 40 ° C., 50 ° C., 60 ° C., 70 ° C., 80 ° C. and 90 ° C. The emission spectrum was measured by irradiating the GaN powder with a laser. The measurement was performed using a He—Cd laser (wavelength: 325 nm), a laser spot having a diameter of 1 mm, and a charge coupled device (CCD) as detection means. The measurement results are shown in FIG.

  As shown in FIG. 5, broad peaks due to vacancy defects were observed at wavelengths of 500 nm to 900 nm. Although light emission was observed even at a wavelength of around 400 nm, it was smaller than the intensity of the peak due to vacancy defects. Further, although the emission intensity changed depending on the measurement temperature, no peak shift was observed.

[Example 2]
<Measurement of emission spectrum of ZnO powder (2)>
A carbon tape having a size of 5 mm × 5 mm was attached to the sample holder, and ZnO powder (manufactured by Kojundo Chemical Co., Ltd., purity 99.999%) was applied thereto. Then, a heater is used as a temperature control means, and the temperature of the ZnO powder is adjusted to 7 types of 26 ° C, 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C, and 95 ° C. The emission spectrum was measured by irradiating laser. The measurement was performed using a He—Cd laser (wavelength: 325 nm), a laser spot having a diameter of 1 mm, and a charge coupled device (CCD) as detection means. As a result, a peak was observed near the wavelength of 390 nm, and the wavelength shifted depending on the temperature at the time of measurement. The measurement results are shown in FIG. In FIG. 6, (a) is the measurement result of the emission spectrum for each temperature at the time of measurement, and (b) is a graph showing the relationship between the peak wavelength and the temperature at the time of measurement.

  As is clear from FIG. 6, it was confirmed that the peak near the wavelength of 390 nm shifted to the long wavelength side as the measurement temperature increased. The shift amount was 4 nm between 26 ° C. and 95 ° C., for example. Moreover, the peak shift amount was slight between 70 ° C. and 95 ° C.

[Example 3]
<Measurement of emission spectrum of NH ₃ heat-treated GaN-ZnO powder>
The emission spectrum was measured in the same manner as in Reference Example 2 except that GaN-ZnO powder heat-treated at 550 ° C. for 5 hours was used instead of GaN powder in an NH ₃ gas atmosphere of 1 atm. The measurement results are shown in FIG. The same ZnO powder as in Example 1 was used, and the same GaN powder as in Reference Example 2 was used.

The emission spectrum of the GaN-ZnO powder reflects the emission spectra of both GaN and ZnO. However, since the emission intensity of GaN is small, this is not clearly recognized in FIG.
On the other hand, as is clear from FIG. 7, the peak near the wavelength of 780 nm did not cause a large difference in intensity as the measurement temperature increased, but shifted to the longer wavelength side, and the shift amount was, for example, 25 ° C. And 6.8 nm between 70 ° C. and 70 ° C.

[Example 4]
<Measurement of emission spectrum of NH ₃ heat-treated TiO ₂ -ZnO powder>
TiO ₂ —ZnO powder (number of moles of TiO ₂ : number of moles of ZnO = 1: 1) was 300 ° C. (Example 4-1) and 400 ° C. (Example 4-2) in an NH ₃ gas atmosphere of 1 atm. ) Or 500 ° C. (Example 4-3), respectively, for 1 hour. As the TiO ₂ powder, one having a purity of 99.99% manufactured by Kojundo Chemical Co., Ltd. was used, and the same one as in Example 1 was used as the ZnO powder. Next, a carbon tape having a size of 5 mm × 5 mm was attached to a sample holder of a scanning electron microscope (SEM), and the NH ₃ -treated TiO ₂ —ZnO powder was applied thereto. Then, an SEM image of the NH ₃ -treated TiO ₂ —ZnO powder was taken under the conditions of a temperature of 25 ° C., an acceleration voltage of 5.0 KV, and a magnification of 10,000 times. The acquired imaging data is shown in FIG. 8A shows imaging data when the heat treatment temperature is 300 ° C., FIG. 8B shows the heat treatment temperature of 400 ° C., and FIG. 8C shows the image data when the heat treatment temperature is 500 ° C.

  As is apparent from FIG. 8, no difference due to temperature was observed in the powder shape. However, when the heat treatment temperature was 300 ° C. and 400 ° C., the powder color was not much different and both were silver white, but when the heat treatment temperature was 500 ° C., the powder color was silver gray. It was noticeably discolored.

Next, using an energy dispersive X-ray spectroscopy (EDX) measuring device, the element concentration of the NH ₃ -treated TiO ₂ —ZnO powder was measured, and the composition was analyzed. The analysis results are shown in Table 1.
As is clear from Table 1, the concentrations of Ti and Zn are remarkably reduced and the concentrations of N and O are more remarkable when the heat treatment temperature is 400 ° C. and 500 ° C. than when the heat treatment temperature is 300 ° C. Had increased.

Next, a carbon tape having a size of 5 mm × 5 mm was attached to the sample holder, and the NH ₃ heat-treated TiO ₂ —ZnO powder was applied thereto. Then, a heater is used as a temperature control means, and the temperature of the powder is adjusted to 8 types of 25 ° C, 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C, 80 ° C and 90 ° C. The powder was irradiated with a laser to measure an emission spectrum. The measurement was performed using a He—Cd laser (wavelength: 325 nm), a laser spot having a diameter of 1 mm, and a charge coupled device (CCD) as detection means. The measurement results are shown in FIG. 9A is a graph showing the emission spectrum measurement results when the heat treatment temperature is 300 ° C., FIG. 9B is the heat treatment temperature 400 ° C., and FIG. 9C is the heat treatment temperature 500 ° C. . In addition, since the application amount of the NH ₃ -treated TiO ₂ —ZnO powder could not be made constant regardless of the heat treatment temperature, it was decided to compare the wavelength of the emission peak for each heat treatment temperature.

  As is apparent from FIG. 9, the emission spectrum varies depending on the heat treatment temperature. In particular, a large difference was observed between the heat treatment temperature of 500 ° C. and the cases of 300 ° C. and 400 ° C. Specifically, it is as follows.

When the heat treatment temperature was 300 ° C., peaks were observed at wavelengths near 550 nm, 630 nm, and 713 nm, respectively. The peak in the vicinity of the wavelength of 550 nm is attributed to an O (oxygen) vacancy defect of ZnO.
On the other hand, when the heat treatment temperature was 400 ° C., peaks were observed at wavelengths near 543 nm and 730 nm, respectively. The peak near the wavelength of 543 nm is caused by O (oxygen) vacancy defects as described above. Thus, it was different from the case where the heat treatment temperature was 300 ° C. in that no peak was observed near 630 nm.
However, at any temperature of 300 ° C. and 400 ° C., the intensity of each peak decreased as the measurement temperature increased.
In addition, at any temperature of 300 ° C. and 400 ° C., a valley of the emission spectrum was observed in the vicinity of the wavelength of 600 nm. The relative magnitude of the emission intensity of this valley portion with respect to the peak intensity is 300 ° C. The case was larger than the case of 400 ° C.

  On the other hand, when the heat treatment temperature was 500 ° C., the intensity of the peak near the wavelength of 540 nm due to the O (oxygen) vacancy defect increased as the temperature increased during measurement. Furthermore, no peak was observed on the longer wavelength side than the wavelength of 570 nm. Therefore, the valley of the emission spectrum near the wavelength of 600 nm observed at 300 ° C. and 400 ° C. was not observed. When the heat treatment temperature was 500 ° C., the powder was noticeably discolored.

[Example 5]
<Measurement of emission spectrum of N ₂ heat-treated TiO ₂ —ZnO powder (1)>
The TiO ₂ -ZnO powder, NH ₃ instead of the gas atmosphere, except that heat treatment under _{N 2} gas atmosphere, the emission spectrum was measured of _TiO 2 -ZnO powder as in Example 4. The measurement results are shown in FIG. 10A is a graph showing the emission spectrum measurement results when the heat treatment temperature is 300 ° C., FIG. 10B is the heat treatment temperature 400 ° C., and FIG. 10C is the heat treatment temperature 500 ° C. .

  As is clear from FIG. 10, the emission spectrum varies depending on the heat treatment temperature, and in particular, a large difference was observed between the heat treatment temperature of 400 ° C. and the cases of 300 ° C. and 500 ° C. Specifically, it is as follows.

When the heat treatment temperature was 300 ° C., peaks were observed at wavelengths near 540 nm, 622 nm, and 714 nm, respectively. The peak in the vicinity of the wavelength of 540 nm is attributed to O (oxygen) vacancy defects in ZnO. And the emission spectrum at this time was the same pattern as the case where the heat processing temperature of Example 4 was 300 degreeC.
On the other hand, when the heat treatment temperature was 500 ° C., peaks were observed at wavelengths near 540 nm, 620 nm, and 716 nm, respectively. The peak around the wavelength of 540 nm is caused by O (oxygen) vacancy defects as described above. And the emission spectrum at this time was the same pattern as the case where said heat processing temperature was 300 degreeC.
In addition, when the heat treatment temperature is 300 ° C., the intensity of each peak is generally reduced as the measurement temperature is increased. However, when the heat treatment temperature is 500 ° C., particularly at a peak near a wavelength of 540 nm, The presence of a temperature range in which the intensity of the peak increases as the measurement temperature increases was observed.

On the other hand, when the heat treatment temperature was 400 ° C., peaks were observed near wavelengths of 545 nm and 703 nm, respectively. The peak in the vicinity of the wavelength of 545 nm is attributed to an O (oxygen) vacancy defect of ZnO. The peaks near the wavelength of 703 nm are on the lower wavelength side than the peaks near 714 nm and 716 nm when the above heat treatment temperatures are 300 ° C. and 500 ° C., and the heat treatment temperatures of Example 4 are 300 ° C. and 400 ° C. Similarly, it was on the lower wavelength side than the peaks near the wavelengths of 713 nm and 730 nm in the case of ° C. Similar to the case where the heat treatment temperature was 300 ° C., the intensity of each peak generally decreased as the measurement temperature increased.
In addition, at any temperature of 300 ° C., 400 ° C., and 500 ° C., a valley of the emission spectrum was observed in the vicinity of the wavelength of 600 nm. The relative difference of the emission intensity of this valley portion with respect to the peak intensity was 400 ° C. The cases were larger than those at 300 ° C and 500 ° C.

[Examples 6 to 7]
<Measurement of emission spectrum of TiO ₂ —ZnO-containing ink and ZnO-containing ink (1)>
The following TiO ₂ —ZnO-containing inks (Example 6, two types: inks 1 to 2) and ZnO-containing inks (Example 7, two types: inks 3 to 4) were prepared and used, and FIG. The two-dimensional code shown in FIG. FIG. 11 is a plan view of a two-dimensional code printed with ink, and a black portion is a printing unit. In addition, as the TiO ₂ —ZnO powder, the same one as used in Example 4 was used, and as the ZnO powder, the same one as used in Example 1 was used.

(Preparation of ink)
Inks 1 to 4 having the following compositions were prepared.
Nitrified cotton (S1 / 4 (N.V. 70%) manufactured by SNPE) 25 parts by mass Plasticizer (Epo-Heiser W-100EL manufactured by Dainippon Ink Co., Ltd.) 6 parts by mass Plasticizer (Mono-Heiser ATBC manufactured by Dainippon Ink Co., Ltd.) 1 mass Part Ethyl acetate 30 parts by mass Toluene 30 parts by mass Isopropyl alcohol 7 parts by mass ZnO powder or TiO ₂ -ZnO powder 1-2 parts by mass In addition, the content of ZnO powder or TiO ₂ -ZnO powder in the inks 1-4 It was as follows.
Ink _1: TiO 2 -ZnO powder 1 part by weight Ink _2: TiO 2 -ZnO powder 2 parts by weight Ink 3: ZnO powder 1 part by weight Ink 4: ZnO powder 2 parts by weight

Next, the two-dimensional code is affixed to a sample holder, a heater is used as a temperature control means, and the temperature of the two-dimensional code is 25 ° C, 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C, 80 ° C. In each case, the emission spectrum was measured by irradiating a 1 mm square part of the cut-out symbol shown in FIG. 11 with a laser. The measurement was performed using a He—Cd laser (wavelength: 325 nm), a laser spot having a diameter of 1 mm, and a charge coupled device (CCD) as detection means. The measurement results are shown in FIGS. FIG. 12 is a graph showing measurement results of emission spectra when using inks 1 to 4 when the temperature at the time of measurement is 25 ° C. in Examples 6 to 7. FIG. 13 is a graph showing the measurement results of the emission spectrum when using the TiO ₂ —ZnO-containing ink of Example 6, where (a) is a graph for ink 1 and (b) is a graph for ink 2. is there. FIG. 14 is a graph showing the measurement results of the emission spectrum when using the ZnO-containing ink of Example 7, wherein (a) is a graph for ink 3 and (b) is a graph for ink 4.

As is clear from FIG. 12, the emission spectra of the inks 1 to 4 all showed the same pattern, and sharp peaks were observed near the wavelengths of 390 nm and 785 nm. In addition, a broad peak was observed at a wavelength of 450 to 700 nm. The emission intensity in the vicinity of a wavelength of 390 nm was larger in the ZnO-containing ink of Example 7 than in the TiO ₂ -ZnO-containing ink of Example 6, and the ink 4 was the largest. Thus, since the emission spectra of the inks 1 to 4 have the same pattern, it was estimated that TiO ₂ —ZnO and ZnO have the same emission mechanism.

As is clear from FIG. 13, when the TiO ₂ —ZnO-containing ink of Example 6 was used, the peak around the wavelength of 785 nm was measured at the measured temperature in both (a) Ink 1 and (b) Ink 2. Although there was no significant difference in the intensity with the increase in, the shift to the long wavelength side was performed, and the shift amount was 12.3 nm between 25 ° C. and 70 ° C., for example. On the other hand, in other peaks, no clear shift was observed as the measured temperature increased. 13A and 13B, a peak is observed in the vicinity of the wavelength of 880 nm, and the intensity is particularly large in FIG. 13B. This is the light generated when the laser light source is switched. This is noise due to the axis deviation.

  As is clear from FIG. 14, when the ZnO-containing ink of Example 7 was used, (a) In ink 3, as in Example 6, the peak near the wavelength of 785 nm was accompanied by an increase in the measurement temperature. Although there was no great difference in intensity, the intensity shifted to the longer wavelength side, and the shift amount was 12.3 nm between 25 ° C. and 70 ° C., for example. On the other hand, in other peaks, no clear shift was observed as the measured temperature increased. On the other hand, in (b) Ink 4, the same result as in Ink 3 was obtained, but the peak in the vicinity of the wavelength of 785 nm was shifted to the longer wavelength side with the increase in measurement temperature, for example, 25 ° C. and 70 ° C. And 7.8 nm.

[Example 8]
<Measurement of emission spectrum of N ₂ heat-treated TiO ₂ —ZnO powder (2)>
The TiO ₂ —ZnO powder used in Example 6 was used, the temperature of the heat treatment in the N ₂ gas atmosphere was only 500 ° C., and the lower limit of the temperature at the time of emission spectrum measurement was 26 ° C. instead of 25 ° C. Except for the above, the emission spectrum of the TiO ₂ —ZnO powder was measured in the same manner as in Example 5. The measurement results are shown in FIG.

As is clear from FIG. 15, the position of the peak of the emission spectrum was the same as that of the TiO ₂ —ZnO-containing ink of Example 6 shown in FIGS. On the other hand, when the TiO ₂ —ZnO powder was heat-treated, when compared with Example 6, the peak near the wavelength of 550 nm was higher in intensity than the other peaks. In addition, a peak near a wavelength of 780 nm was not observed when the measurement temperature was high.

[Example 9]
<NH ₃ Measurement of the emission spectrum of the heat-treated ZnO powder>
The emission spectrum was measured in the same manner as in Example 4 except that instead of NH ₃ heat-treated TiO ₂ —ZnO powder, ZnO powder heat-treated at 500 ° C. for 1 hour in an NH ₃ gas atmosphere of 1 atm was used. . The measurement results are shown in FIG. In addition, the same thing as Example 1 was used as ZnO powder.

  As is clear from FIG. 16, the position of the peak of the emission spectrum and the state of the shift depending on the measured temperature were the same as in the case of the ZnO-containing ink of Example 7 shown in FIGS. On the other hand, by heating the ZnO powder, the intensity of the peak near the wavelength of 700 nm was increased as compared with Example 7.

On the other hand, as is clear from FIGS. 15 to 16, the emission spectra of Examples 8 and 9 showed patterns symmetrical to each other. In Example 8, the heat treatment was performed in an N ₂ gas atmosphere as an inert gas, whereas in Example 9, the heat treatment was performed in a highly active NH ₃ gas atmosphere, resulting in O (oxygen). It is presumed that the difference in the amount of vacancy defects is reflected in such a difference in emission spectrum.

[Examples 10 to 11]
<Measurement of emission spectrum of TiO ₂ —ZnO-containing ink and ZnO-containing ink (2)>
Except for using the ink 2 in Example 6 and printing the two-dimensional code shown in FIG. 11 on the paper surface of the paper on which the carbon thin film was laminated instead of paper, there were 8 ways as in Example 6. The emission spectrum was measured at temperature (Example 10). Note that the paper on which the carbon thin film is laminated has an effect of releasing electric charges, unlike ordinary paper, so that it can be expected to improve the measurement accuracy of the emission spectrum.
Further, in the same manner as in Example 7, except that the two-dimensional code shown in FIG. 11 was printed on the paper surface of the paper laminated with the carbon thin film using the ink 4 in Example 7, the same as in Example 7. The emission spectrum was measured at the same temperature (Example 11).
The measurement results are shown in FIGS. FIG. 17 is a graph showing the measurement results of the emission spectrum when using the TiO ₂ —ZnO-containing ink (ink 2) of Example 10, and FIG. 18 shows the ZnO-containing ink (ink 4) of Example 11. It is a graph which shows the measurement result of the emission spectrum at the time of using.

As is clear from FIG. 17, the emission spectrum when using the ink 2 of Example 10 is the same peak position as the emission spectrum when using the ink 2 of Example 6 shown in FIG. 13B. showed that. However, no noise near the wavelength of 880 nm observed in FIG. 13B was observed.
Further, as in the case of Example 6, the peak near the wavelength of 780 nm did not cause a large difference in intensity as the measurement temperature increased, but shifted to the longer wavelength side, and the shift amount was, for example, 25 It was 14 nm (783.5 nm-769.5 nm) between 0 degreeC and 90 degreeC. On the other hand, in other peaks, no clear shift was observed as the measured temperature increased.

On the other hand, as is clear from FIG. 18, the emission spectrum when the ink 4 of Example 11 is used is the same as the emission spectrum when the ink 4 of Example 7 shown in FIG. 14B is used. The peak position is shown.
Further, as in the case of Example 7, the peak near the wavelength of 785 nm did not cause a large difference in intensity as the measurement temperature increased, but shifted to the longer wavelength side, and the shift amount was, for example, 25 It was 11 nm (794.7 nm-783.7 nm) between 0 degreeC and 90 degreeC. On the other hand, in other peaks, no clear shift was observed as the measured temperature increased.

  INDUSTRIAL APPLICABILITY The present invention can be used in all technical fields that use functions as light emitting elements, such as optical communication devices and information identification sensors.

Claims (6)

Light emitting means comprising a pressurized heat-treated zinc oxide, and temperature control means for adjusting the temperature of the light emitting means, a pumping means for irradiating excitation light to the light emitting means, detecting means for detecting the emission spectrum of the light emitting means Are temperature-variable optical sensor elements configured separately or in one body,
The light emission means shows a different emission spectrum depending on the temperature at the time of excitation light irradiation, and the emission spectrum when the excitation light is irradiated by the excitation means to the light emission means whose temperature is adjusted by the temperature adjustment means By measuring with the detection means, information unique to the substrate holding the light emitting means is obtained from the combination of the peak pattern, peak intensity or trough intensity in the obtained emission spectrum. Optical sensor element. Light emitting means comprising a pressurized heat-treated zinc oxide, and temperature control means for adjusting the temperature of the light emitting means, a pumping means for irradiating excitation light to the light emitting means, detecting means for detecting the emission spectrum of the light emitting means Are temperature-variable optical sensor elements configured separately or in one body,
The light emitting means has a light emission intensity that increases with an increase in temperature during excitation light irradiation, and the light emitting means whose temperature is adjusted by the temperature adjusting means is irradiated with excitation light by the excitation means. By measuring the emission intensity with the detection means, information specific to the substrate holding the emission means is obtained from the combination of the peak pattern, peak intensity or valley intensity in the obtained emission spectrum. Variable temperature optical sensor element.   The temperature variable optical sensor element according to claim 1 or 2, wherein a peak position in the emission spectrum is shifted depending on a temperature at the time of excitation light irradiation.   The temperature-variable optical sensor element according to any one of claims 1 to 3, further comprising zinc oxide that has been heat-treated in the presence of an inert gas or ammonia gas.   The temperature-variable optical sensor element according to any one of claims 1 to 4, wherein the light emitting means further contains gallium nitride or titanium dioxide.   The light emitting means includes a dispersion obtained by dispersing the zinc oxide or heat-treated zinc oxide in water or a water-soluble liquid, or a layer formed by applying and drying the dispersion. The temperature variable optical sensor element according to any one of claims 1 to 5.