JP2015117147A - Production method of glass member, and glass member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a glass member, with which the glass member having optical characteristics of glass changed such that an antireflection effect is obtained by forming a microstructure with a dimension smaller than the wavelength of light on a surface of an optical member and controlling the refractive index in a pseudo manner, is easily produced, and to provide the glass member.SOLUTION: Since a first step to plasma-etch a surface of a glass substrate 2 including one or more elements selected from an alkali metal, an alkaline earth metal, and a rare earth metal by using a fluorine-based gas is included in a production method, a fluoride layer 4 is formed on the surface of the glass substrate 2 in the first step, the fluoride layer 4 functions as a mask, and a part covered with the mask remains without being plasma-etched and becomes a protrusion 3 having the fluoride layer 4 on the tip thereof. Thereby a glass member 1 having optical characteristics of glass changed is easily produced only by a plasma etching treatment.

Description

  The present invention relates to a method for producing a glass member and a glass member, and particularly to an optical member for a solar cell.

  Solar cells are attracting attention as a source of clean electrical energy, and improvement in power generation efficiency is desired. As a method of improving the power generation efficiency of the solar cell, for example, the light transmitted through the optical member is increased by suppressing reflection that occurs at the interface between the optical member such as the cover glass, the transparent electrode, and the homogenizer of the solar cell and the air. A method for increasing the light applied to the cell has been studied. As a method for changing the optical characteristics of the optical member, for example, a technique for obtaining an antireflection effect by controlling the refractive index in a pseudo manner by forming a fine structure smaller than the wavelength of light on the surface of the optical member. Has been proposed (for example, Patent Document 1).

  Patent Document 1 discloses a method for obtaining a high antireflection performance by providing a two-dimensional uneven structure having a wavelength equal to or less than the minimum wavelength of light to be prevented from being reflected on a transparent substrate.

JP 2013-2317779 A

  However, in the method disclosed in Patent Document 1, in order to form an antireflection structure, a resist is exposed by photolithography or electron beam lithography to produce a mask, and the surface of the glass substrate is etched using the mask. The manufacturing process of the antireflection structure is complicated.

  Then, in view of said problem, it aims at providing the manufacturing method and glass member of a glass member which can manufacture easily the glass member which changed the optical characteristic of glass.

  The glass member according to claim 1 of the present invention includes a plurality of convex portions formed integrally with the base body on at least one surface of the base body made of glass, and the convex portions are alkali metal and alkaline earth. It has the fluoride layer containing 1 or more chosen from the fluoride of a metal and rare earths in the front-end | tip part.

  A solar cell according to claim 7 of the present invention is characterized by using the glass member according to any one of claims 1 to 6.

  The method for producing a glass member according to claim 8 of the present invention includes plasma etching the surface of a glass substrate containing one or more elements selected from alkali metals, alkaline earth metals, and rare earths using a fluorine-based gas. The 1st process to be provided is provided, It is characterized by the above-mentioned.

  The glass member according to claim 1 of the present invention includes a plurality of convex portions formed integrally with the base on at least one surface of the base formed of glass, and the convex portions include an alkali metal, an alkaline earth metal, and Since the tip portion has a fluoride layer containing one or more selected from rare earth fluorides, the optical characteristics change.

  The solar battery according to claim 7 of the present invention can change the characteristics of the optical member formed of glass, and can efficiently collect light in the solar battery cell. Therefore, power generation efficiency can be improved.

  The method for producing a glass member according to claim 8 of the present invention includes plasma etching the surface of a glass substrate containing one or more elements selected from alkali metals, alkaline earth metals, and rare earths using a fluorine-based gas. Since the first layer is provided, a fluoride layer is formed on the surface of the glass substrate during the first step, the fluoride layer functions as a mask, and the portion covered by the mask remains without being etched. Thus, a convex portion having a fluoride layer at the tip end portion is formed. Therefore, it is possible to easily manufacture a glass member whose optical characteristics are changed only by a plasma etching process.

It is a schematic sectional drawing which shows the convex part of the glass member of 1st Embodiment. It is a schematic sectional drawing which shows the convex part of the glass member of 2nd Embodiment. It is a figure which shows the transmittance | permeability of the light of each wavelength in the glass member of Example 1. FIG. It is a figure which shows the diffuse reflectance in the glass member of Example 2. FIG. It is a figure which shows the optical characteristic of the glass member of Example 3, and the lens of Example 3 before an etching process, FIG. 5A is the transmittance | permeability of the light of each wavelength in the lens of Example 3 before an etching process, FIG. It is a figure which shows the transmittance | permeability of the light of each wavelength in the glass member of Example 3. It is a figure which shows the surface shape of the glass member of an Example, FIG. 6A is the surface shape of the glass substrate before the etching process of Example 1, FIG. 6B is the surface shape of the glass member after the etching process of Example 1, FIG. FIG. 6D is an AFM image showing the surface shape of the glass member after the etching process of Example 2, and FIG. It is a cross-sectional SEM photograph which shows the cross-sectional shape of the glass member after the etching process of Example 1, and the glass member created by changing only the etching time by CHF ₃ among the manufacturing conditions of Example 1, FIG. 7A glass members etching time of 20 minutes by CHF _3, as shown in FIG. 7B is a glass member etching time of 30 minutes by CHF _3, after the etching process of FIG. 7C is CHF ₃ etching time by 40 minutes of the glass member (example 1 glass members) in FIG. 7D glass member etching time of 60 minutes by CHF _3, FIG. 7E is a cross-sectional SEM photograph of the glass member 80 minute etching time by CHF _3. It is a figure which shows the result of the composition analysis of the surface of the glass member of the Example by XPS, FIG. 8A is the analysis result of the glass substrate before the etching process of Example 1, and the glass member after the etching process of Example 1, FIG. These are figures which show the analysis result of the glass member before an etching process, and the glass member after the etching process of Example 2. FIG. It is a figure which shows the analysis result of the composition of the glass member after the etching process of Example 1 by STEM-EDX, FIG. 9A is a cross-sectional TEM photograph of the glass member after an etching process, FIG. 9B is the area | region 1 shown to FIG. FIG. 9C is a diagram showing the EDX analysis result of region 2 shown in FIG. 9A. It is a figure which shows the compositional analysis result of the glass member after the etching process of Example 1 by STEM-EDX, FIG. 10A is a cross-sectional TEM photograph of the glass member after the etching process of Example 1, and FIG. 10C is a diagram showing the F distribution, FIG. 10D is the Si distribution, FIG. 10E is the Ca distribution, and FIG. 10F is a diagram showing the results of EDX analysis showing the Na distribution. It is a photograph which shows the result of the evaluation experiment of the characteristic with respect to the water of the glass member of Example 1, FIG. 11A is the experimental result about the glass substrate before an etching process, FIG. 11B is about the glass member after the etching process of Example 1. FIG. As a result of the experiment, FIG. 11C is a photograph showing the experiment result of the glass member after the etching treatment of Example 1 subjected to the water repellent treatment, the right figure in each figure is a photograph taken from the side, and the left figure is diagonally upward. This is a photograph taken as seen from above. It is a figure which shows the evaluation result of the characteristic of the solar cell which used the glass member after the etching process of Example 1 for the homogenizer.

1. Glass Member of First Embodiment (1) Configuration of Glass Member As shown in FIG. 1, the glass member 1 of the first embodiment includes a base 2 and a plurality of convex portions 3 formed on at least one surface of the base 2. Is provided. The substrate 2 is made of glass, and the shape thereof can be any shape such as a plate shape, a lens shape having a curved surface, and a spherical shape.

  The convex portion 3 has a columnar shape and is formed integrally with the base body 2. The length of the convex portion 3 is 50 to 150 nm, and the length from the surface of the base 2 to the tip of the convex portion 3 is 300 to 500 nm. That is, the convex portion 3 has an aspect ratio of 2 to 10 represented by a value obtained by dividing the length from the surface of the base 2 to the tip of the convex portion 3 by the length of the diameter of the convex portion 3. It has a high shape. Such convex portions 3 are irregularly arranged on the surface of the base 2 with an interval of 5 to 30 nm.

  Moreover, the convex part 3 has the fluoride layer 4 which has as a main component the fluoride of one element chosen from Ca, Mg, Sr, Ba, and Ce in the front-end | tip part. The fluoride layer 4 is formed integrally with the convex portion 3 as a part of the convex portion 3. The fluoride layer refers to a region where the concentration of fluoride as a main component is 30% or more.

Moreover, the convex part 3 contains SiO ₂ , and SiO ₂ is distributed so that the density increases from the tip part of the convex part 3 toward the surface of the substrate 2.

  In addition, the glass member 1 may be provided with the convex part 3 which has the above characteristics only on one surface, and may be provided also on the other surface.

(2) Manufacturing method of glass member The manufacturing method of a glass member has the 1st process of plasma-etching the surface of a glass base material using fluorine-type gas.

  The first step will be described. First, a glass substrate containing at least one element selected from alkaline earth metals and rare earths Ca, Mg, Sr, Ba, and Ce is prepared. As the glass substrate, a glass substrate having an arbitrary shape such as a plate shape, a lens shape having a curved surface, or a spherical shape can be used.

After the prepared glass substrate is washed and dried, the glass substrate is placed in the chamber of the etching apparatus, and the inside of the chamber is evacuated. Thereafter, a fluorine-based gas as an etching gas is flowed into the chamber at a predetermined flow rate to maintain the chamber at a predetermined pressure. As the fluorine-based gas, it is preferable to use a gas containing at least one selected from CHF ₃ , CF ₄ , NF ₃ , SF ₆ , XeF ₂ , and NH ₄ F.

  Subsequently, plasma is generated in the chamber with a predetermined high-frequency output, and the surface of the glass substrate is plasma etched for a predetermined time to complete the first step. In the case of the first embodiment, since ions of elements such as Ca have a large ion radius, they tend to stay on the surface of the glass substrate even when ionized by plasma etching. Therefore, a fluoride layer is formed on the surface of the glass substrate. And since the fluoride containing elements such as Ca has a high boiling point and lattice energy, the fluoride layer is hardly decomposed once formed. Therefore, the fluoride layer functions as a mask, and the unmasked portion is etched to form the convex portion 3. The glass member is manufactured through the above first step.

Further, the method for manufacturing a glass member includes a step of plasma-etching the surface of a glass substrate that has been plasma-etched with a fluorine-based gas using oxygen (O ₂ ) gas in order to remove carbides adhering to the surface. You may have two processes.

The second step will be described. After the first step, the inside of the chamber is evacuated again, and O ₂ gas is allowed to flow at a predetermined flow rate as an etching gas to maintain the pressure in the chamber at a predetermined pressure. Subsequently, plasma is generated in the chamber with a predetermined high-frequency output, and the surface of the glass substrate is plasma etched for a predetermined time.

  Further, after the first step or the second step, the manufactured glass member may be washed with water to remove impurities attached to the surface.

  Furthermore, the glass member which provided the convex part 3 on both surfaces can be manufactured by turning over the manufactured glass member, arrange | positioning in a chamber, and repeating said manufacturing process again.

(3) Action and Effect In the above configuration, the glass member 1 of the first embodiment includes a plurality of convex portions 3 formed integrally with the base body 2 on the surface of the base body 2 made of glass, and the convex portions. 3 has a diameter of 50 nm to 150 nm, a length from the surface of the substrate 2 to the tip of the convex portion 3 of 300 to 500 nm, and one element selected from Ca, Mg, Sr, Ba, and Ce The refractive index gradually changes at the interface of the glass member 1 because the fluoride layer 4 having the fluoride as a main component is provided at the tip. Therefore, since the refractive index difference between the inside and the outside of the glass member 1 becomes small at the interface of the glass member 1, it is possible to suppress the reflection of light at the interface of the glass member 1, and the optical characteristics of the glass change. The light transmittance is improved over a wide wavelength range.

Further, in the glass member 1, the convex portion 3 includes SiO ₂ and is configured such that the density of SiO ₂ increases from the fluoride layer 4 toward the base 2, so that the refractive index of the light of the convex portion 3 is flat. It gradually increases from the chemical compound layer 4 toward the substrate 2, and the change in the refractive index at the interface of the glass member 1 becomes more gradual. Therefore, the refractive index difference between the inside and the outside of the glass member 1 becomes small at the interface of the glass member 1, light reflection at the interface of the glass member 1 can be suppressed, and the light transmittance can be further improved.

  Thus, since the glass member 1 of 1st Embodiment has the high light transmittance in a wide wavelength range, it can be used for the homogenizer, Fresnel lens, cover glass, etc. of a concentrating solar cell.

  Furthermore, in the glass member 1, since the convex part 3 was comprised irregularly on the surface of the base | substrate 2, it can suppress that the interference fringe by a light diffraction phenomenon arises.

  In the manufacturing method of the glass member 1, the surface of the glass substrate containing at least one selected from alkaline earth metals and rare earths Ca, Mg, Sr, Ba, Ce is plasma-etched using a fluorine-based gas. It comprised so that the 1st process might be provided. Therefore, the fluoride layer 4 is formed on the surface of the glass substrate during the first step, the fluoride layer 4 functions as a mask, and the portion covered with the mask remains unetched and remains at the tip. The protrusion 3 having the fluoride layer 4 is formed. Therefore, it is possible to easily manufacture the glass member 1 in which the optical characteristics are changed only by the plasma etching process, that is, the light transmittance is improved. Moreover, since it is not necessary to separately form a mask, the glass member 1 with changed optical characteristics can be easily manufactured even if a glass substrate having a curved surface is used.

In the manufacturing method of a glass member 1, the surface of the glass substrate was plasma etched using a fluorine-based gas, by performing the second step of plasma etching using O ₂ gas, to the surface of the glass substrate The adhered carbide is oxidized and removed by etching with O ₂ , and the light transmittance can be further improved.

2. Glass Member of Second Embodiment (1) Configuration of Glass Member As shown in FIG. 2, the glass member 5 of the second embodiment includes a base 2 and a plurality of convex portions 3 formed on at least one surface of the base 2. Is provided. The substrate 2 is made of glass and can have any shape such as a plate shape, a lens shape having a curved surface, or a spherical shape.

  The convex portion 3 has an island shape with a flat surface, and is formed integrally with the base 2. The convex part 3 has a diameter of 500 nm to 1 μm, and a length from the surface of the base 2 to the tip of the convex part 3 is about 500 nm. Such convex portions 3 are irregularly arranged on the surface of the base 2 with an interval of 20 to 300 nm.

  Moreover, the convex part 3 has the fluoride layer 4 which has as a main component the fluoride of one element chosen from Na and Li which are alkali metals in the front-end | tip part. The fluoride layer 4 is formed integrally with the convex portion 3 as a part of the convex portion 3.

  In addition, the glass member 5 may be provided with the convex part 3 which has the above characteristics only on one surface, and may be provided also on the other surface.

  The manufacturing method of the glass member 5 according to the second embodiment is different from the manufacturing method of the glass member 1 according to the first embodiment in that a glass substrate including one or more selected from Na and Li is used as the glass substrate. However, since other points are the same as the manufacturing method of the glass member 1, the description is omitted. In the case of the second embodiment, ions of elements such as Na have a large ion radius, so that they tend to stay on the surface of the glass substrate even when ionized by plasma etching. Therefore, a fluoride layer is formed on the surface. And since a fluoride containing elements such as Na has a relatively low boiling point and lattice energy, a part thereof is ionized again. Reionization and fluorination occur repeatedly, and ions such as Na accumulate and the area of the fluoride layer increases. Since a part of the fluoride that has not been reionized functions as a mask as the fluoride layer, the convex portion 3 is formed.

(2) Action and Effect In the above-described configuration, the glass member 5 of the second embodiment includes a plurality of convex portions 3 formed integrally with the base body 2 on the surface of the base body 2 made of glass. 3 has a diameter of 500 nm to 1 μm, a length from the surface of the substrate 2 to the tip of the protrusion 3 of about 500 μm, and a fluoride of one element selected from Na and Li as a main component. Since the front end portion of the fluoride layer 4 is configured so that light is scattered by the convex portions 3 on the surface of the glass member 5, the optical characteristics of the glass member change, that is, the light at the interface of the glass member 5 changes. Diffuse reflectance increases. Thus, the glass member 5 of 2nd Embodiment can be used for the back surface reflective electrode etc. of a solar cell since light diffusely reflects.

Process for producing a glass member 5, Na, the surface of the glass substrate that includes one or more selected from _{Li, CHF 3, CF 4,} NF 3, SF 6, XeF 2, NH 4 1 or more selected from F The first step of performing plasma etching using a fluorine-based gas containing is included. Therefore, the fluoride layer 4 is formed on the surface of the glass substrate during the first step, the fluoride layer 4 functions as a mask, and the portion covered with the mask remains unetched and remains at the tip. The protrusion 3 having the fluoride layer 4 is formed. Therefore, it is possible to easily manufacture the glass member 5 in which the optical characteristics are changed only by the plasma etching process, that is, the diffuse reflectance of light is increased. In addition, since it is not necessary to form a mask separately, the glass member 5 having changed optical characteristics can be easily manufactured even if a glass substrate having a curved surface is used.

In the manufacturing method of a glass member 5, the surface of the glass substrate was plasma etched using a fluorine-based gas, by performing the second step of plasma etching using O ₂ gas, to the surface of the glass substrate The deposited carbide is oxidized and removed by etching with O ₂ , and the optical characteristics can be changed.

3. Example (1) Production of glass member In Example 1, a glass substrate (B270 (registered trademark), 76.0 mm × 26.0 mm × 1.1 mm, manufactured by SCHOTT) having a composition shown in Table 1 as a glass substrate. Hereinafter, the glass member of 1st Embodiment was produced using the glass substrate A.).

First, the glass substrate A was put into a cleaning solution containing 1 wt% of a cleaning agent (product name: Contaminone (registered trademark)) manufactured by Wako Pure Chemical Industries, Ltd., and ultrasonically cleaned for 30 minutes. Thereafter, the cleaned glass substrate was ultrasonically cleaned with ultrapure water produced by an ultrapure water apparatus (product name: Milli-Q) manufactured by Millipore for 30 minutes. After the cleaned glass substrate was dried at 80 ° C. for 10 hours, it was placed in the chamber of an etching apparatus (product name: DEA-507L) manufactured by Anelva, and the inside of the chamber was evacuated. Thereafter, CHF ₃ was flowed into the chamber at a flow rate of 75 sccm to maintain the pressure in the chamber at 2 Pa. Subsequently, plasma was generated in the chamber with a high frequency output of 800 W, and the surface of the glass substrate A was reactive plasma etched for 40 minutes to produce a glass member etched with CHF ₃ .

Further, in Example 1, after etching with CHF ₃ , the inside of the chamber was evacuated, and O ₂ gas was allowed to flow into the chamber at a flow rate of 50 sccm to maintain the pressure in the chamber at 4 Pa. Subsequently, plasma was generated in the chamber at a high frequency output of 200 W, and the surface of the glass substrate was reactive plasma etched for 10 minutes. Thus, a glass member that was etched with CHF ₃ and O ₂ (hereinafter referred to as an etching process) was produced.

  Moreover, the glass member after the etching treatment was immersed in the above-described ultrapure water, subjected to ultrasonic cleaning for 5 minutes, naturally dried at room temperature, and a water-washed glass member was produced.

  Furthermore, the glass member which performed the etching process similarly on the back surface of the glass member after an etching process was produced. The glass member was also washed with water after the etching treatment.

As described above, in Example 1, four types of glass members were produced: a glass member etched with CHF ₃ , a glass member after etching treatment, a glass member subjected to water washing treatment, and a glass member subjected to etching treatment on both sides. did.

In Example 2, a glass substrate made of SCHOTT (D263 (registered trademark), hereinafter referred to as glass substrate B) having the same size as the glass substrate A and having the composition shown in Table 1 was used as the glass substrate. The glass member of 2 embodiment was produced. In Example 2, a glass member etched with CHF ₃ and a glass member after the etching treatment were produced under the same manufacturing conditions as in Example 1.

  In Example 3, the glass member of 1st Embodiment was produced using the lens of the diameter 30mm which has the same composition as the glass substrate A and the curved surface was formed in the single side | surface as a glass base material. The glass member of Example 3 was produced by performing an etching process under the same conditions as the manufacturing conditions of the glass member of Example 1.

(2) Evaluation of glass member (2-1) Evaluation of optical property (2-1-1) Evaluation of optical property of glass member of Example 1 First, a glass member etched with CHF ₃ and glass after etching treatment About the member, the glass member which performed the washing process, and the glass member which performed the etching process on both surfaces, the light transmittance was measured and the optical characteristic was evaluated. The light transmittance was calculated by irradiating the glass member with collimated (parallel) light having a diameter of 1 cm, measuring the intensity of the light transmitted through the glass member, and dividing the measured value by the intensity of the collimated light. At this time, the wavelength of the collimated light was changed in the range of 400 to 1000 nm, the intensity of the transmitted light was repeatedly measured, and the light transmittance was measured. For comparison, the light transmittance of the glass substrate A was also measured.

FIG. 3 shows the transmittance of light of each wavelength in the glass member of Example 1. The horizontal axis represents the wavelength of light, and the vertical axis represents the light transmittance. In the figure, “glass substrate” is the measurement result of glass substrate A, “after CHF ₃ etching” is the glass member etched with CHF ₃ , “after O ₂ etching” is the measurement result of the glass member after etching treatment “After washing” represents the measurement result of the glass member subjected to the washing treatment, and “Double-side treatment” represents the measurement result of the glass member subjected to the etching treatment on both sides.

As shown in FIG. 3, the light transmittance of the glass member etched with CHF ₃ is higher than that of the glass substrate A except for light having a wavelength close to 400 nm. Therefore, it was confirmed that a glass member with improved light transmittance could be produced only by plasma etching.

Further, the glass member after the etching treatment has improved transmittance of light having a wavelength close to 400 nm. This is because the carbide adhering to the surface of the glass substrate was oxidized by O ₂ and removed from the surface of the glass substrate A. As a result, the light transmittance of the glass member of Example 1 was improved over the entire measured wavelength region as compared with the glass substrate A. Therefore, it was confirmed that a glass member with further improved light transmittance could be produced by etching with O ₂ .

  Moreover, as shown in FIG. 3, the light transmittance of the glass member that has been washed with water is higher in the entire measured wavelength region than the glass member after the etching treatment. This is because impurities and the like attached to the surface of the glass member are removed by washing with water. Thus, the light transmittance can be improved by washing the glass member with water.

  Then, the light transmittance of the glass member subjected to the etching treatment on both surfaces is measured in comparison with the glass member after the etching treatment and the glass member subjected to the water washing treatment, that is, the glass member subjected to the etching treatment only on one side. The transmittance is high over the entire wavelength range and close to 99%. Thus, the light transmittance of the glass member can be further improved by etching both surfaces of the glass member.

(2-1-2) Evaluation of optical characteristics of glass member of Example 2 Next, the diffuse reflectance of the glass member etched with CHF ₃ of Example 2 and the glass member after the etching treatment was measured to obtain glass. The optical properties of the members were evaluated. The glass member was irradiated with light in the same manner as the light transmittance measurement, and the diffuse reflectance was measured. For comparison, the diffuse reflectance of the glass substrate B was also measured.

FIG. 4 shows the diffuse reflectance in the glass member of Example 2. The horizontal axis represents the wavelength of light, and the vertical axis represents the diffuse reflectance. In the figure, “glass substrate” is the measurement result of glass substrate B, “after CHF ₃ etching” is the glass member etched with CHF ₃ , “after O ₂ etching” is the measurement result of the glass member after etching treatment Represents.

As shown in FIG. 4, the diffuse reflectance was improved as compared with the glass substrate B by performing etching or etching treatment with CHF ₃ . From the above, it was confirmed that a glass member with improved diffuse reflectance could be produced only by plasma etching.

(2-1-3) Evaluation of optical characteristics of glass member of Example 3 Finally, the light transmittance of the glass member of Example 3 was measured to evaluate the optical characteristics. The optical characteristics of the glass member of Example 3 were measured at three locations, that is, the center of the lens and a position shifted by 5 mm to the left and right from the center of the lens. The measurement method is the same as the light transmittance measurement method of Example 1. For comparison, the same measurement was performed on the lens before the etching process.

  FIG. 5A shows the transmittance of light of each wavelength in the lens before the etching treatment, and FIG. 5B shows the transmittance of light of each wavelength in the glass member of Example 3. 5A and 5B, the horizontal axis represents the wavelength of light, and the vertical axis represents the light transmittance. In the figure, Center, Left and Right indicate the measurement positions of the light transmittance. Comparing FIG. 5A and FIG. 5B, the glass member of Example 3 has an increased light transmittance over the entire wavelength region measured regardless of the measurement position as compared with the lens before the etching treatment. I understand that. From the above, it was confirmed that the method for producing a glass member can be applied to a glass member having a curved surface.

(2-2) Evaluation of surface shape of glass member About the glass member after the etching process of Example 1 and Example 2, atomic force microscope (AFM, product name: Nanonavi Station / E-sweep) made by SII Nanotechnology Was used to observe the etched surface of the glass member, and the surface shape was evaluated. For comparison, the surfaces of the glass substrate A and the glass substrate B were also observed by AFM.

  6A is an AFM image showing the surface shape of the glass substrate A, and FIG. 6B is an AFM image showing the surface shape of the glass member after the etching process of Example 1. FIG. The white line shown in the figure is an index indicating a length of 1 μm. Moreover, the strip | belt-shaped parameter | index shown by the lower part in a figure is an parameter | index showing a height difference. Comparing FIG. 6A and FIG. 6B, it can be seen that a convex portion having a diameter of about 50 to 150 nm is formed on the surface of the base of the glass member by the etching process. Moreover, as shown to FIG. 6B, it turns out that the said convex part is arrange | positioned irregularly on the surface of the base | substrate of a glass member.

  6C is an AFM image showing the surface shape of the glass substrate B, and FIG. 6D is an AFM image showing the surface shape of the glass member after the etching process of Example 2. FIG. Comparing FIG. 6C and FIG. 6D, the etching process resulted in a convex portion having a diameter of 500 nm to 1 μm and a length from the surface of the glass member base to the tip of about 500 μm on the surface of the glass member base. It can be seen that it was formed. Moreover, as shown to FIG. 6D, it turns out that the said convex part was formed irregularly at intervals of 20-300 nm on the surface of the base | substrate of a glass member.

Furthermore, in order to evaluate in detail the shape of the convex part formed in the surface of the glass member of Example 1, the cross section of the glass member after the etching process of Example 1 is made into FE-SEM (product name: Hitachi High-Technologies Corporation). S-4700). At this time, among the manufacturing conditions of the glass member after the etching treatment of Example 1, a glass member in which only the etching time with CHF ₃ was changed to 20 minutes, 30 minutes, 60 minutes, and 80 minutes was produced, and the step surface was similarly formed. Was observed, and the change in the shape of the convex portion due to the etching time was evaluated.

7A is CHF ₃ by etching time 20 minutes the glass member, Figure 7B is CHF ₃ by etching time of 30 minutes the glass member, Fig. 7C etching time of 40 minutes after the etching treatment of the glass member (Example 1 glass member), Fig. 7D glass member 60 minutes the etching time by CHF _3, Figure 7E etching time by CHF ₃ shows a cross-sectional SEM photograph of 80 minutes the glass member. As shown in FIG. 7C, the convex part of the glass member after the etching treatment of Example 1 has a diameter of about 50 to 150 nm, and the length from the surface of the base of the glass member to the tip of the convex part. It has a columnar shape of about 300 to 500 nm and is formed integrally with the base of the glass member with an interval of about 5 to 30 nm. Further, as shown in FIGS. 7A to 7E, the length from the surface of the base of the glass member to the tip of the convex portion becomes longer as the etching time by CHF ₃ becomes longer. Even when other plasma etching conditions such as high-frequency plasma output are changed, the length from the surface of the base of the convex glass member to the tip of the convex changes.

(2-3) Evaluation of the composition of the convex part of a glass member In order to evaluate the composition of a convex part, first, the composition of the surface of the glass member after the etching process of Example 1 and Example 2 was analyzed by X-ray photoelectron spectroscopy. Analysis by (XPS). For comparison, the surface composition of glass substrate A and glass substrate B was also analyzed by XPS. AlK-α was used as the X-ray.

  FIG. 8A shows the analysis result of the composition of the glass member after the etching process of Example 1 and the analysis result of the composition of the glass substrate A. The dark solid line shown in the figure is the analysis result of the glass member after the etching process of Example 1, and the light solid line is the analysis result of the glass substrate A. As shown in FIG. 8A, in the glass substrate A, Si2p, Si2s and O1s peaks were observed, and other small NaKLL peaks were observed. Since no other peak is observed, it can be seen that the surface of the glass substrate A mainly contains Si and O, and then contains a large amount of Na. Therefore, Si mainly bonds with O, and the surface of the glass substrate A mainly contains silicon oxide.

On the other hand, in the glass member after the etching treatment of Example 1, the Si2p, Si2s, and O1s peaks were smaller than those of the glass substrate A, and Ca2p, Ca2s, and F1s peaks newly appeared. This is because Ca and F are mainly contained in the tip of the convex portion formed on the surface of the glass member, that is, the surface of the base of the glass member, by etching with CHF ₃ and etching with O _2. Means that Therefore, the distal end portion of the convex portion, since the elements contained in the non-Ca and F is small, Ca is primarily bound to F, contains calcium fluoride (Ca x _{F y).}

  FIG. 8B shows the analysis result of the glass member after the etching process of Example 2 and the analysis result of the glass substrate B. As shown in FIG. 8B, in the glass substrate B, Si2p, Si2s, and O1s peaks were observed, and other small NaKLL peaks were observed. Since no other large peak is observed, it can be seen that the surface of the glass substrate B mainly contains Si and O, and then contains a large amount of Na. Therefore, Si mainly bonds with O, and the surface of the glass substrate B mainly contains silicon oxide.

On the other hand, in the glass member after the etching treatment of Example 2, the Si2p, Si2s, and O1s peaks were smaller than that of the glass substrate B, the NaKLL peak was larger, and a new F1s peak appeared. This is because Na and F are mainly contained in the surface of the glass member, that is, the tip of the convex portion formed on the surface of the base of the glass member by etching with CHF ₃ and etching with O _2. It means that. Therefore, the distal end portion of the convex portion, since the small elements contained in addition to Na and F, Na are mainly bound to F, contains sodium fluoride (Na x _{F y)} is.

In order to analyze the composition of the convex part of the glass member of Example 1 in more detail, the glass after the etching treatment of Example 1 using a scanning transmission electron microscope (STEM, product name: HD-2700) manufactured by Hitachi High-Technologies Corporation The cross section of the member was observed, and the composition of the convex portion was analyzed using an energy dispersive X-ray analyzer (EDX, product name: Genesis) manufactured by EDAX. 9A is a cross-sectional TEM photograph of the glass member after the etching process of Example 1. FIG. The composition of the two regions of the tip of the convex portion (region 1 surrounded by a square shown in FIG. 9A) and between the tip of the convex portion and the base of the glass member (region 2 shown in FIG. 9A). Was analyzed by EDX. The results are shown in FIGS. 9B and 9C. FIG. 9B shows the EDX analysis result of region 1, and FIG. 9C shows the EDX analysis result of region 2. As shown in FIG. 9B, it can be seen that in region 1, Ca and F are detected more than other elements, and Ca _x F _y is mainly included at the tip of the convex portion. On the other hand, as shown in FIG. 9C, in region 2, Si and O are detected more than other elements, and silicon oxide is mainly formed between the tip of the convex portion and the base of the glass member. It can be seen that it is included.

  Next, the distribution of elements contained in the convex portions of the glass member after the etching treatment of Example 1 was analyzed using the above EDX. 10A is a cross-sectional TEM photograph of the glass member after the etching treatment of Example 1, FIG. 10B is a distribution of O, FIG. 10C is a distribution of F, FIG. 10D is a distribution of Si, FIG. 10E is a distribution of Ca, and FIG. Is the result of EDX analysis showing the distribution of Na. The white line shown in the figure is an index indicating a length of 1 μm.

As shown in FIG. 10C, F is concentrated and distributed at the tip of the convex portion. Further, as shown in FIG. 10E, Ca is also concentrated and distributed at the tip of the convex portion. That is, the tip of the convex portion contains a large amount of Ca and F, and this result agrees with the analysis result by XPS and the analysis result of EDX described above. From the above results, it can be seen that a layer mainly composed of Ca _x F _y is formed at the tip of the convex portion of the glass member.

Moreover, as shown to FIG. 10B, O is little at the front-end | tip part of a convex part, and it is distributed so that it approaches the surface of the base | substrate of a glass member. Similarly, as shown in FIG. 10D, Si is also less at the tip of the convex portion and is more distributed as it approaches the surface of the substrate of the glass member. As described above, silicon oxide is mainly contained between the tip of the convex portion and the base of the glass member. From this result, silicon oxide is transferred from the tip of the convex portion to the surface of the base of the glass member. It turns out that it is distributed so that a density becomes high toward it. Since the glass substrate A contains SiO ₂ at a rate of 70.0% as silicon oxide, the silicon oxide is an oxide mainly composed of SiO ₂ .

  As for Na, no characteristic distribution was observed as shown in FIG. 10F.

(2-4) Evaluation of water repellency of glass member In order to evaluate the water repellency of the glass member, water drops were dropped on the surface of the glass member after the etching treatment of Example 1, and the shape thereof was observed. For comparison, the glass substrate (glass substrate A) before etching treatment and (CH ₃ O) ₃ SiCH ₂ CH ₂ CF ₃ mixed in methanol at a ratio of 1 wt% are immersed in methanol for 24 hours for water repellent treatment. The same experiment was performed on the glass member after the etching treatment of Example 1 in which the above was performed.

  FIG. 11A is a photograph showing the experimental results for the glass substrate A before the etching treatment, and 8 in the figure shows the glass substrate A. The right figure is a photograph taken from the side, and the left figure is a photograph taken as if looking down obliquely from above. As shown in FIG. 11A, the glass base material A before the etching process is installed on the pedestal 7, and water droplets 11 a are dropped on the glass base material A. Since the water droplet 11a is hemispherical, it can be seen that the glass substrate A has water repellency.

  FIG. 11B is a photograph showing the experimental results for the glass member 9 after the etching process of Example 1. As shown to FIG. 11B, the water droplet dripped at the surface of the glass member 9 after the etching process of Example 1 becomes a film | membrane form, and the glass member 9 after the etching process of Example 1 has hydrophilicity. You can see that This is because fine convex portions are formed on the surface of the glass member.

  FIG. 11C is a photograph showing an experimental result on the glass member 10 after the etching treatment of Example 1 subjected to the water repellent treatment. As shown to FIG. 11C, the water droplet 11b dripped at the surface of the glass member 10 after the etching process of Example 1 which performed water-repellent treatment is hemispherical, and the glass member after the etching process of Example 1 is It can be seen that the water repellency treatment has resulted in water repellency. Therefore, it was confirmed that the glass member after the etching treatment of Example 1 could be subjected to water repellent treatment.

(3) Solar cell using glass member for homogenizer A concentrating solar cell includes, for example, a condensing unit composed of a Fresnel lens, a homogenizer for homogenizing sunlight collected by the condensing unit, and a solar cell. Etc. In the concentrating solar cell, the sunlight condensed by the condensing part is irradiated and homogenized by a homogenizer provided on the solar cell, and the uniformed sunlight is irradiated to the solar cell. Generate electromotive force. Here, the concentrating solar cell which used the glass member for the homogenizer was produced, and the characteristic of the said solar cell was evaluated.

First, a glass substrate made by Dr. Optics (LIBA2000) having almost the same composition as the glass substrate A is etched under the same conditions as in Example 1 to produce a glass member, and the glass member is used as a homogenizer. A concentrating solar cell (hereinafter referred to as solar cell SOE2) was produced. Moreover, CHF ₃ condensing type with a glass member to produce a high-frequency plasma power during the etching under the same conditions as SOE2 except that a 1000W homogenizer by the solar cell (hereinafter, referred to as solar cell SOE1.) Were also prepared. The light receiving surface of the homogenizer was etched. Moreover, the produced homogenizer is substantially hemispherical, and the light receiving surface is a curved surface.

Then, the prepared concentrating solar cell is installed outdoors, shorts when sunlight is irradiated to the condensing type solar cell current density J _SC and the power generation efficiency Eff. And the characteristics of the solar cell were evaluated. Power generation efficiency Eff and the short-circuit current density _{J SC.} Measured twice at different times.

  For comparison, a concentrating solar cell (hereinafter referred to as a solar cell Ref.) Using the glass substrate before the etching treatment as a homogenizer was produced, and its characteristics were similarly evaluated.

The evaluation result of the produced solar cell is shown in FIG. SOE1 shown in the figure represents the measurement result of the solar cell SOE1, and SOE2 represents the measurement result of the solar cell SOE2. The 4-digit number on the horizontal axis in the figure represents the measurement time. The vertical axis in the figure represents the solar cell Ref. The short-circuit current density _{J SC} value when the reference for representing the rate of change of the value of the short circuit current density _{J SC} of SOE1 or SOE2. That, (SOE1 or SOE2 the short-circuit current density _{J SC} -. Short-circuit current density _{J SC} of the solar cell Ref) / solar cell Ref. It is a value represented by the short circuit current density _JSC . Power generation efficiency Eff. The same applies to.

As shown in FIG. 12, SOE1 and SOE2 together regardless of the measurement time, short-circuit current density _{J SC} and the power generation efficiency Eff. Since rate of change is a positive value, by etching, a short circuit current density J _SC and the power generation efficiency Eff. It can be seen that has increased. From the above results, it was confirmed that the power generation efficiency of the solar cell could be improved by using the glass member for the solar cell.

4). The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the gist of the present invention. For example, conditions for plasma etching with a fluorine-based gas, conditions for plasma etching with O ₂ , a glass substrate cleaning method, a glass member water washing method, a glass member water repellent treatment method, and the like can be changed as appropriate.

  In the above embodiment, the case where the glass member is used for the homogenizer of the concentrating solar cell has been described. However, the present invention is not limited to this. For example, the condensing member of the solar cell (Fresnel lens or the like) ), A glass member can also be used for a cover glass, a transparent electrode, a back surface reflecting electrode, and the like.

Further, in the above embodiment, the case where the glass member after the etching treatment of Embodiment 1 is subjected to the water repellent treatment has been described, but the present invention is not limited to this, and the glass member etched with CHF ₃ is used. Further, the water repellent treatment may be applied to the glass member subjected to the water washing treatment and the glass member subjected to the etching treatment on both surfaces.

In the above embodiment, the case where a glass member produced by etching a glass substrate having the same composition as that of the glass substrate A under the same conditions as in the embodiment 1 is used as a homogenizer has been described. Not limited to this, a glass member produced by etching the glass substrate with CHF ₃ may be used, and the homogenizer may be washed with water. Further, in addition to the light receiving surface, the surface from which light is emitted from the homogenizer may be etched. Moreover, you may produce a solar cell using the glass member produced by etching-processing the glass base material which has the same composition as the glass substrate B on the same conditions as Example 2, as a homogenizer. Further, the shape of the homogenizer can be appropriately changed. For example, the light receiving surface may be a flat surface.

1, 5, 9, 10 Glass member 2 Base 3 Protrusion 4 Fluoride layer 7 Base 8 Glass substrate A

Claims (13)

A plurality of protrusions formed integrally with the base body are provided on at least one surface of the base body made of glass,
The convex part has a fluoride layer containing one or more selected from alkali metal, alkaline earth metal and rare earth fluoride at the tip part.   The glass member according to claim 1, wherein the fluoride layer is mainly composed of a fluoride of one element selected from Ca, Mg, Sr, Ba, and Ce.   The glass member according to claim 1, wherein the fluoride layer is mainly composed of a fluoride of one element selected from Na and Li. The convex portion includes a SiO _2, glass member according to claim 2, characterized in that the density of the SiO ₂ is increased from the fluoride layer toward the substrate.   5. The glass member according to claim 2, wherein the convex portion has a columnar shape and is irregularly disposed on a surface of the base.   The ratio of the length from the surface of the base to the tip of the convex portion and the length of the diameter of the convex portion is 2 to 10 in the convex portion. Glass member.   The solar cell using the glass member of any one of Claims 1-6.   A glass member comprising a first step of performing plasma etching on a surface of a glass substrate containing one or more elements selected from alkali metals, alkaline earth metals, and rare earths using a fluorine-based gas. Method. The method for producing a glass member according to claim 8, wherein the fluorine-based gas includes one or more selected from CHF ₃ , CF ₄ , NF ₃ , SF ₆ , XeF ₂ , and NH ₄ F.   The said glass base material contains 1 or more chosen from Ca, Mg, Sr, Ba, Ce, Na, Li, The manufacturing method of the glass member of Claim 8 or 9 characterized by the above-mentioned.   The method for producing a glass member according to any one of claims 8 to 10, further comprising a second step of performing plasma etching on the surface of the glass substrate using oxygen gas.   The method for producing a glass member according to any one of claims 8 to 11, further comprising a third step of washing the glass member with water.   The method for producing a glass member according to claim 8, wherein the glass member is subjected to water repellent treatment.

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