JP7396416B2 - Glass substrate with transparent conductive film and method for manufacturing the same - Google Patents

Description

The present invention relates to a glass substrate with a transparent conductive film and a method for manufacturing the same. The present invention particularly relates to a glass substrate with a transparent conductive film that is suitably used for low emissivity glass, transparent electrode substrates for solar cells, etc., and a method for manufacturing the same.

Glass substrates with transparent conductive films, in which transparent conductive films containing metal oxides, etc. are formed on glass substrates, have various properties and are used in a wide range of fields such as architectural components, optical parts, electrical parts, and electronic parts. has been done.

Glass substrates with transparent conductive films are used, for example, as low emissivity glass having heat shielding properties, for glass windows of buildings, vehicles, etc., frozen showcases, cooking utensils, and the like. It is generally known that low emissivity glass has excellent heat shielding properties when the resistance of the transparent conductive film is relatively low.

Furthermore, the glass substrate with a transparent conductive film is also used as a transparent electrode substrate for solar cells. Solar cells are elements that directly convert light energy from the sun into electrical energy, and are broadly classified into silicon-based, compound-based, III-V group-based, and organic-based. Also in transparent electrode substrates for solar cells, the electrical resistance value of the transparent conductive film is required to be relatively small from the viewpoint of improving cell efficiency. Two factors are related to the electrical resistance value: carrier concentration and mobility of the transparent conductive film. In this field, high mobility is required to reduce the loss of incident light transmittance as much as possible.

As described above, glass substrates with transparent conductive films used for various purposes are sometimes subjected to treatments including high-temperature processes. For example, in order to impart strength to low-emissivity glass, air-cooling strengthening, which includes a step of heating the low-emissivity glass at a high temperature of about 600 to 700° C., is sometimes performed.

Furthermore, transparent electrode substrates for solar cells are sometimes subjected to treatments including high-temperature processes during the manufacture of solar cells. One of the compound-based solar cells in the solar cell described above is a CdTe solar cell in which Cd.Te is used as a raw material. Generally, a CdTe solar cell has a structure in which a transparent electrode substrate is used as a cathode, and an n-type layer, a p-type layer, and an anode are laminated in this order on the transparent electrode substrate. Here, the p-type layer is generally made of CdTe, but since films made of CdTe are generally formed in a high-temperature environment, the transparent electrode substrate is also placed in a high-temperature environment in the production of CdTe solar cells. That will happen.

For example, in Patent Document 1, a heat-resistant substrate surface and a material surface mainly composed of CdTe and/or Cd and Te are installed in close proximity, the material surface is heated to generate gas, and the material surface is heated at a lower temperature than the material surface. In a method for forming a CdTe film in which CdTe is deposited on the surface of a certain heat-resistant substrate, heating the material surface to a temperature of 630° C. or higher is disclosed.
Further, from the viewpoint of film forming speed, film quality, battery efficiency, etc., it is preferable that the heating temperature during CdTe film formation is high, and forming CdTe into a film in an environment of about 700° C. is also being considered.

Japanese Patent Application Publication No. 10-247625

However, when such a glass substrate with a transparent conductive film is processed under high-temperature conditions of 650° C. to 700° C., the resistance of the transparent conductive film increases and the characteristics in various applications may deteriorate. Therefore, heat resistance at high temperatures has been required for glass substrates with transparent conductive films.

In view of such circumstances, the present invention aims to provide a transparent electrode substrate that has excellent heat resistance at high temperatures.

The present invention relates to the following 1 to 7.
1. A glass substrate with a transparent conductive film comprising a glass substrate, an undercoat layer and a transparent conductive film in this order,
The undercoat layer includes a layer containing silicon oxide as a main component,
The main component of the transparent conductive film is _SnO2 ,
The transparent conductive film contains fluorine atoms as a dopant,
A glass substrate with a transparent conductive film, which has a resistance change ratio of 2 or less as determined by the following formula 1 in a heat resistance test held at a maximum temperature of 700° C. for 116 minutes in a nitrogen atmosphere.
(Formula 1) Resistance change ratio = (sheet resistance value of transparent conductive film after heat resistance test) / (sheet resistance value of transparent conductive film before heat resistance test)
2. 2. The glass substrate with a transparent conductive film according to 1 above, wherein the relationship between the carrier concentration of the transparent conductive film and the amount of fluorine ions per 1 cm ³ of the transparent conductive film satisfies the following formula 2.
(Formula 2) Carrier concentration (cm ^-3 ) > 0.45 x amount of fluorine ions (cm ^-3 ) + 1.5 x 10 ²⁰
3. 2. The glass substrate with a transparent conductive film as described in 2 above, wherein the carrier concentration is 2.0×10 ²⁰ cm ⁻³ or more.
4. 4. The glass substrate with a transparent conductive film according to any one of 1 to 3 above, wherein the free electron mobility in the transparent conductive film is 32 cm ² /Vs or more.
5. 5. The glass substrate with a transparent conductive film according to any one of 1 to 4 above, wherein the free electron mobility in the transparent conductive film is 38 cm ² /Vs or more.
6. 6. The glass substrate with a transparent conductive film according to any one of 1 to 5 above, wherein the undercoat layer has the following configuration (a) or (b).
(a) A structure in which a layer containing SiO ₂ as a main component and a layer containing TiO ₂ or SnO ₂ as a main component are laminated.
(b) A structure consisting of a layer mainly composed of SiOC or SiON.
7. 7. With a transparent conductive film according to any one of 1 to 6 above, comprising sequentially forming the undercoat layer and the transparent conductive film on the glass substrate by a CVD (Chemical Vapor Deposition) method. A method for manufacturing a glass substrate.

According to the glass substrate with a transparent conductive film of the present invention, the resistance change ratio in the heat resistance test is small, so that the glass substrate has excellent heat resistance at high temperatures of, for example, 650° C. to 700° C. Therefore, the glass substrate with a transparent conductive film of the present invention is suitably used for applications that can be subjected to treatments including high-temperature processes, such as low emissivity glass, transparent electrode substrates for solar cells, and the like.

FIG. 1 is a schematic cross-sectional view showing a configuration example of a glass substrate with a transparent conductive film. FIG. 2 is a diagram showing the distribution of the resistance change ratio, with the horizontal axis representing the carrier concentration and the vertical axis representing the mobility. FIG. 3 is a diagram showing the distribution of the resistance change ratio, with the horizontal axis representing the amount of fluorine ions and the vertical axis representing the carrier concentration. FIG. 4 is a diagram showing the distribution of the resistance change ratio, with the horizontal axis representing the thickness of the transparent conductive film and the vertical axis representing the fluorine uptake rate. FIG. 5 is a schematic cross-sectional view showing a configuration example of a CdTe solar cell.

The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and can be implemented with arbitrary modifications within the scope of the gist of the present invention. In addition, "~" indicating a numerical range is used to include the numerical values written before and after it as a lower limit value and an upper limit value.

<Glass substrate with transparent conductive film>
As shown in FIG. 1, the glass substrate 1 with a transparent conductive film according to this embodiment includes a glass substrate 10, an undercoat layer 30, and a transparent conductive film 20 in this order.
In the glass substrate 1 with a transparent conductive film according to the present embodiment, the undercoat layer 30 includes a layer containing silicon oxide as a main component, the main component of the transparent conductive film 20 is SnO ₂ , and the transparent conductive film 20 is used as a dopant. Contains fluorine atoms.

The glass substrate with a transparent conductive film according to the present embodiment has a resistance change ratio of 2 or less as determined by the following formula 1 in a heat resistance test held at a maximum temperature of 700° C. for 116 minutes in a nitrogen atmosphere.
(Formula 1) Resistance change ratio = (sheet resistance value of transparent conductive film after heat resistance test) / (sheet resistance value of transparent conductive film before heat resistance test)
Since the glass substrate with a transparent conductive film according to the present embodiment has such a resistance change ratio of 2 or less, an increase in sheet resistance value is suppressed even when a process including a high temperature process of 650° C. to 700° C. is performed, for example. and has excellent heat resistance. The resistance change ratio is preferably 1.5 or less, more preferably 1.25 or less. Further, the resistance change ratio is preferably as small as possible, but is typically 1 or more.
Hereinafter, the glass substrate with a transparent conductive film according to this embodiment will be described in more detail.

(Transparent conductive film)
In the glass substrate with a transparent conductive film according to this embodiment, the main component of the transparent conductive film is SnO ₂ and the transparent conductive film contains fluorine atoms as a dopant. The components constituting the transparent conductive film will be described in more detail later.

In the transparent conductive film, it is preferable that the relationship between the carrier concentration and the amount of fluorine ions per 1 cm ³ of the transparent conductive film satisfies the following formula 2.
(Formula 2) Carrier concentration (cm ^-3 ) > 0.45 x amount of fluorine ions (cm ^-3 ) + 1.5 x 10 ²⁰
As a result of the following study, the present inventors found that the carrier concentration in the transparent conductive film and the amount of fluorine ions per 1 ^cm3 of the transparent conductive film (hereinafter also simply referred to as "the amount of fluorine ions") are expressed by the above formula 2. It has been found that by satisfying the relationship, the heat resistance of the glass substrate with a transparent conductive film can be easily improved. Here, the amount of fluorine ions per 1 cm ³ of the transparent conductive film refers to the number of fluorine ions per 1 cm ³ of the transparent conductive film. For example, the fluorine concentration (weight %) in the transparent conductive film is measured and the following formula It can be calculated by
Amount of fluorine ions = (fluorine concentration (weight%)/100) x (density of transparent conductive film (g/cm ³ )) ÷ 18.988 x 6.022 x 10 ²³
Here, the density of the transparent conductive film is 6.95 g/cm ³ when the transparent conductive film is a fluorine-doped SnO ₂ film. Further, the atomic weight of F is 18.998, and Avogadro's number is 6.022×10 ²³ .

First, the present inventors have developed a method in which carrier concentration and free electron mobility (hereinafter also simply referred to as "mobility"), which are elements that determine the resistance value of a transparent conductive film, have various values. After adjusting the conditions, a transparent conductive film was formed by a CVD method to produce a glass substrate with a transparent conductive film, and the resistance change ratio was examined for each glass substrate with a transparent conductive film. FIG. 2 shows the distribution of the resistance change ratio, with the horizontal axis representing the carrier concentration and the vertical axis representing the mobility. In FIG. 2, four types of markers are shown, which are color-coded according to the value of the resistance change ratio, and in descending order of resistance change ratio (Rs ratio), marker A (1.03≦Rs ratio≦1.50), marker A (1.03≦Rs ratio≦1.50), They are referred to as marker B (1.50<Rs ratio≦2), marker C (2<Rs ratio≦3), and marker D (3<Rs ratio≦6.11). Here, the resistance change ratio of markers A and B is 2 or less, and the resistance change ratio of markers C and D is greater than 2. Note that similar markers are used in FIGS. 3 and 4, which will be described later.

According to FIG. 2, in the region where the mobility is lower than 38 cm ² /Vs, the resistance change ratio is approximately 2 or less, but in the region where the mobility is 38 cm ² /Vs or more, the magnitude of the resistance change ratio is It was found that classification based on concentration or mobility values was not possible.
Therefore, the present inventors calculated the distribution of resistance change ratio for a glass substrate with a transparent conductive film having a mobility of 38 cm ² /Vs or higher, with the horizontal axis representing the amount of fluorine ions and the vertical axis representing the carrier concentration, as shown in Figure 3. investigated. Then, only markers A and B are distributed in the region that satisfies the above formula 2 (in FIG. 3, the region where the carrier concentration is higher than the dotted line), and almost only markers C and D are distributed in the region that does not satisfy the above formula 2. The result was that.

Therefore, if (Formula 2) carrier concentration (cm ^-3 ) > 0.45 x amount of fluorine ions (cm ^-3 ) + 1.5 x 10 ²⁰ is satisfied, the resistance change ratio tends to become small in the glass substrate with a transparent conductive film. It was found that heat resistance was easily improved. This result is considered to mean that the higher the proportion of fluorine atoms that contribute to carrier generation among the fluorine atoms contained in the transparent conductive film, the better the heat resistance is.

FIG. 4 is a diagram showing the distribution of the resistance change ratio for each glass substrate with a transparent conductive film similar to that shown in FIG. It is.
Here, the fluorine uptake rate refers to a value expressed by the following equation 3.
(Formula 3) Fluorine uptake rate = (XRF F/Sn)/(HF/MBTC)
(XRF F/Sn): Ratio of F signal intensity to Sn signal intensity of a transparent conductive film determined by X-ray fluorescence analysis (XRF) (HF/MBTC): Monobutyltin trichloride (MBTC) supplied to the CVD device The molar ratio of hydrogen fluoride (HF) to the transparent conductive film after film formation, that is, the fluorine uptake ratio, is the molar ratio of hydrogen fluoride (HF) to This is a value that relatively represents the proportion of the amount of fluorine incorporated into the membrane.

According to FIG. 4, it can be seen that markers A and B are clustered and distributed in a region where the fluorine uptake rate is relatively low. This result means that when excessive fluorine atoms are incorporated into the transparent conductive film, such as when the fluorine incorporation ratio is relatively high, the heat resistance tends to decrease.
In addition, when examining the relationship between resistance change ratio and film thickness in Figure 4, markers A and B are widely distributed from a film thickness of about 420 nm to around 550 nm, so film thickness is considered not to be a factor that limits heat resistance. It will be done.

The relationship between excess fluorine atoms and heat resistance is considered as follows. That is, when fluorine atoms doped into a transparent conductive film containing SnO ₂ as a main component replace the oxygen sites of SnO ₂ and are incorporated into the transparent conductive film, they emit free electrons and contribute to carrier generation. However, when excessive fluorine atoms are incorporated into the transparent conductive film, the excess fluorine atoms do not replace oxygen sites and tend to exist in interstitial spaces or at grain boundaries of SnO ₂ . It is thought that such fluorine atoms do not contribute to carrier generation, and their chemical bonds are in a relatively unstable state. In a high-temperature environment, such fluorine atoms become activated, causing defects and distortions in the SnO ₂ lattice. As a result, carrier concentration and mobility tend to decrease due to high-temperature heating, and as a result, it is thought that the resistance value increases, that is, the resistance change ratio increases.

For the above reasons, if the above formula 2 is satisfied and the proportion of fluorine atoms that contribute to carrier generation among the fluorine atoms contained in the transparent conductive film is relatively large, the resistance will change because there are few fluorine atoms that do not contribute. It is thought that the ratio can be reduced and heat resistance can be improved. Note that FIGS. 3 and 4 were studied for glass substrates with transparent conductive films having a mobility of 38 cm ² /Vs or more, but as mentioned above, it is thought that the rate of fluorine uptake is related to heat resistance. Therefore, it is considered that the glass substrate with a transparent conductive film tends to have excellent heat resistance by satisfying Formula 2 regardless of the mobility.

In the transparent conductive film, a method for adjusting the relationship between the carrier concentration and the amount of fluorine ions to satisfy Equation 2 is not particularly limited, but includes, for example, a method of adjusting the supply ratio of raw materials for the transparent conductive film. Specific preferable conditions will be described later.

Sheet resistance is important as an electrical property of a transparent conductive film. Sheet resistance is the electric resistance as a substantial transparent conductive film defined by specific resistance/film thickness. By adjusting the specific resistance and film thickness, the sheet resistance can be set to a preferable value. The sheet resistance is preferably 20 Ω/□ or less, more preferably 12 Ω/□ or less from the viewpoint of reducing voltage loss in wiring as a transparent electrode substrate and improving heat shielding properties as a low emissivity glass. The lower the sheet resistance, the better, but 5Ω/□ or more is practical. The sheet resistance can be measured, for example, by a four-point needle measuring device or by a Hall effect measuring device.

The specific resistance of the transparent conductive film is preferably 0.001 Ωcm or less, more preferably 0.0008 Ωcm or less, and even more preferably 0.0006 Ωcm or less, from the viewpoint of increasing the conductivity as a glass substrate with a transparent conductive film. Further, the lower the specific resistance of the transparent conductive film, the more preferable it is, but 0.0001 Ωcm or more is practical. Note that the specific resistance of the transparent conductive film can be determined from the sheet resistance value and film thickness using a four-point needle measuring device for a glass substrate with a transparent conductive film.

Note that the thickness of the transparent conductive film is preferably 450 nm or less, more preferably 400 nm or less, from the viewpoint of suppressing an increase in haze, for example, when a glass substrate with a transparent conductive film is used for low emissivity glass. Further, from the viewpoint of not increasing the resistance too much, the film thickness is preferably 200 nm or more, and more preferably 300 nm or more.

For example, when a glass substrate with a transparent conductive film is used as a transparent electrode substrate for a solar cell, the thickness is preferably 800 nm or less, more preferably 600 nm or less, from the viewpoint of ensuring high light transmittance. Further, the film thickness is preferably 300 nm or more, more preferably 400 nm or more, from the viewpoint of not increasing the resistance too much. The thickness of the transparent conductive film can be measured using a stylus type step meter or a fluorescent X-ray analyzer.

From the viewpoint of reducing the sheet resistance of the transparent conductive film, the free electron mobility in the transparent conductive film is preferably 32 cm ² /Vs or more, more preferably 38 cm ² /Vs or more, and even more preferably 45 cm ² /Vs or more. Mobility is important both when using a glass substrate with a transparent conductive film as a low emissivity glass and when using it as a transparent electrode substrate for solar cells, and a relatively large value is required.

Since low emissivity glass is required to have a small haze, the thickness of the transparent conductive film tends to be limited. On the other hand, as described above, in order to improve heat shielding properties, the sheet resistance of the transparent conductive film is required to be low. Therefore, from the viewpoint of reducing the sheet resistance without increasing the film thickness, it is preferable that the specific resistance is relatively small.

Moreover, in a transparent electrode substrate for a solar cell, by having a structure in which the carrier concentration is relatively low and the mobility is high, a transparent electrode substrate with excellent transmittance in the near-infrared region can be obtained. A transparent electrode substrate with excellent transmittance in the near-infrared region is preferable because it facilitates increasing the current of the solar cell. Therefore, it is preferable that the mobility is relatively high.
The higher the mobility, the better, but the practical upper limit is about 52 cm ² /Vs.

The carrier concentration of the transparent conductive film is preferably 2.0 × 10 ²⁰ cm ^-3 or more, more preferably 2.5 × 10 ²⁰ cm ^-3 or more, from the viewpoint of ensuring conductivity as a glass substrate with a transparent conductive film. More preferably, it is 3.0×10 ²⁰ cm ⁻³ or more. From the viewpoint of increasing conductivity, the higher the carrier concentration is, the more preferable it is, but the practical upper limit is about 4.0×10 ²⁰ cm ⁻³ . By setting the carrier concentration to the above upper limit value or less, an increase in absorption rate in a long wavelength region can be suppressed, and a decrease in transmittance of a glass substrate with a transparent conductive film can be suppressed. The carrier concentration and mobility of the transparent conductive film can be measured using a Hall effect measuring device.

The main component of the transparent conductive film is _SnO2 . The main component of the transparent conductive film means 50% by weight or more of the components constituting the transparent conductive film, preferably 70% by weight or more, and 85% by weight based on the entire transparent conductive film. It is more preferable that it is above. Further, the upper limit of the proportion of the main component in the transparent conductive film is not particularly limited, but 99.9% by weight or less is practical.

The transparent conductive film has light transmittance and conductivity as a glass substrate with a transparent conductive film, and may contain other components in addition to the main component SnO ₂ as long as the effects of the present invention are achieved. Examples of other components include ZnO, In ₂ O ₃ , TiO ₂ , Ga ₂ O ₃ and the like.

The transparent conductive film contains fluorine atoms as a dopant.
The fluorine concentration in the transparent conductive film is preferably 0.01% by weight or more, more preferably 0.015% by weight or more, and 0.02% by weight or more from the viewpoint of ensuring conductivity as a glass substrate with a transparent conductive film. More preferred. On the other hand, from the viewpoint of suppressing excessive fluorine uptake into the transparent conductive film, the fluorine concentration is preferably 0.2% by weight or less, more preferably 0.15% by weight or less, and even more preferably 0.1% by weight or less.

The composition and fluorine concentration of the transparent conductive film can be identified and measured by X-ray fluorescence analysis (XRF), X-ray photoelectron spectroscopy (XPS), or secondary ion mass spectrometry (SIMS). In this specification, as the fluorine concentration, a value measured by X-ray fluorescence analysis (XRF) according to the method described in Examples is used.

(undercoat layer)
The glass substrate 1 with a transparent conductive film according to this embodiment includes an undercoat layer 30 between the glass substrate 10 and the transparent conductive film 20. By providing the undercoat layer 30, diffusion of alkali metal components and the like from the glass substrate 10 to the transparent conductive film 20 can be prevented, and deterioration of the transparent conductive film 20 can be suppressed. Furthermore, by adjusting the refractive index of the undercoat layer 30, it is possible to suppress reflection of light at the interface between the transparent conductive film and the glass substrate due to the difference in refractive index between the glass substrate 10 and the transparent conductive film 20.

The undercoat layer includes a layer containing silicon oxide as a main component. Examples of the layer containing silicon oxide as a main component include a layer containing SiO ₂ , SiOC, or SiON as a main component. The undercoat layer may be a mixed film or a laminated film of these, or may be a laminated film with a layer other than a layer whose main component is a silicon oxide layer. Examples of layers other than the layer containing the silicon oxide layer as the main component include layers containing TiO ₂ , SnO ₂ , etc. as the main component. Specific preferable examples of the undercoat layer include (a) a laminated structure of a layer containing SiO ₂ as the main component and a layer containing TiO ₂ or SnO ₂ as the main component, and (b) SiOC or SiON. Examples include a structure having only a layer containing as a main component.
Here, a layer containing a certain component as a main component means that the certain component accounts for 50% by weight or more, preferably 70% by weight or more, and 85% by weight of the components constituting the layer. It is more preferable that it is above. Moreover, the upper limit of the content of a certain component as a main component is not particularly limited, and may be 100% by weight.

The thickness of the undercoat layer is preferably 10 nm or more, more preferably 20 nm or more, in order to suitably obtain the above-mentioned effects. Further, from the viewpoint of suppressing light absorption by the undercoat layer itself, the thickness is preferably 100 nm or less, more preferably 80 nm or less.

(Glass substrate)
The glass substrate can be the same as that conventionally used for transparent electrode substrates for solar cells or low emissivity glasses. Examples include glass substrates containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , MgO, CaO, SrO, BaO, ZrO ₂ , Na ₂ O and K ₂ O as a base composition. More specifically, in terms of mole percentage based on oxides, SiO ₂ is 60 to 75%, Al ₂ O ₃ is 1 to 7.5%, B ₂ O ₃ is 0 to 1%, and MgO is 8.5%. ~12.5%, CaO 1-6.5%, SrO 0-3%, BaO 0-3%, ZrO ₂ 0-3%, Na ₂ O 1-8%, K ₂ O Examples include glass substrates containing 2 to 12%. However, the composition is not limited to these.

Considering the power generation efficiency of solar cells and the light transmittance of low emissivity glass, the glass substrate preferably has an average transmittance of 90.3% or more for light with a wavelength of 500 to 800 nm, and 90.4% when converted to a thickness of 2 mm. The ratio is more preferably 90.5% or more, and even more preferably 90.5% or more.

Moreover, it is preferable that the glass substrate has good heat resistance.
Specifically, the glass softening temperature is preferably 680°C or higher, more preferably 700°C or higher, and even more preferably 710°C or higher. On the other hand, in order to avoid excessively increasing the viscosity during melting, the glass softening temperature is preferably 850°C or lower, more preferably 800°C or lower, and even more preferably 780°C or lower.

Furthermore, the average coefficient of thermal expansion of the glass substrate at 50 to 350°C is preferably 70×10 ^-7 /°C or higher, and 80×10 ^-7 /°C or higher in order to prevent the module from warping when modularized. is more preferable. On the other hand, from the viewpoint of suppressing peeling and the like, the temperature is preferably 95×10 ⁻⁷ /°C or less, more preferably 90×10 ⁻⁷ /°C or less.

The thickness of the glass substrate is not particularly limited, but from the viewpoint of strength and transmittance, it is preferably 0.7 mm or more, more preferably 1.1 mm or more, and preferably 6.0 mm or less, and more preferably 4.0 mm or less. preferable.

<Method for manufacturing glass substrate with transparent conductive film>
The glass substrate 1 with a transparent conductive film is obtained by sequentially forming an undercoat layer 30 and a transparent conductive film 20 on a glass substrate 10.
Specifically, glass substrates are produced through a melting process in which glass raw materials are heated to obtain molten glass, a fining process in which bubbles are removed from the molten glass, a forming process in which the molten glass is shaped into a plate to obtain a glass ribbon, and a glass ribbon is heated at room temperature. It is obtained through a slow cooling step of slow cooling to a state of Alternatively, a glass substrate may be manufactured by forming molten glass into a block shape, slowly cooling it, and then cutting and polishing it.

For each of the above steps, conventionally known methods can be used. The manufacturing method is not limited to the embodiments, and can be modified and improved as appropriate within the scope of achieving the purpose of the present invention.

An undercoat layer is formed on a glass substrate, and then a transparent conductive film is formed.
Both the undercoat layer and the transparent conductive film are formed using CVD (Chemical Vapor
It can be formed by a chemical vapor deposition method, a sputtering method, a chemical plating method, a wet coating method, or the like. The sputtering method is a method of forming a film on a manufactured glass substrate, and the chemical plating method is a method that is also used when making mirrors. Among the methods for forming the undercoat layer and the transparent conductive film, the CVD method is preferred, and the atmospheric pressure CVD method described below is more preferred.

Atmospheric pressure CVD methods include online CVD methods and offline CVD methods.
The online CVD method is a method of forming a film directly on the surface of glass during the manufacturing process of glass substrates on a float line. That is, instead of forming a transparent conductive film or the like after obtaining a glass substrate, a transparent conductive film or the like is formed during the process of obtaining a glass substrate.
Specifically, during the production of glass substrates, glass ribbons are moved over a molten tin bath and then slowly cooled to produce glass substrates continuously. , a process of forming a desired layer on the top surface of the glass ribbon is continuously carried out.

More specifically, before the slow cooling process in the above glass substrate manufacturing method, that is, while the glass on the float line is still hot during the molding process, a gaseous raw material is blown onto the glass surface and reacted. A glass substrate with a transparent conductive film can be obtained by forming a desired layer.
The online CVD method is preferable because it allows the undercoat layer and the transparent conductive film to be formed continuously in a series of steps for manufacturing the glass substrate, thereby keeping manufacturing costs low.

On the other hand, in the offline CVD method, the glass that has been manufactured through the glass manufacturing process and cut to an appropriate size is fed into an electric furnace and transported while reacting the gaseous raw materials in the same way as in the online CVD method. This is a method of forming a desired layer using the following method. Although this method has the advantage of being able to set the transport speed and substrate temperature in accordance with film formation, the manufacturing cost is higher than that of the online CVD method.

In the case of the CVD method, the thickness of the undercoat layer and transparent conductive film is controlled by the type of raw material, the concentration of the raw material gas, the flow rate of the raw material gas sprayed onto the glass ribbon, the substrate temperature, the residence time of the reactive gas derived from the coating beam structure, etc. can.

As a method for forming an undercoat layer by CVD, for example, a glass substrate heated to a temperature of 500 to 800° C. is reacted with a gaseous raw material to form a layer containing silicon oxide as a main component on the glass substrate. A method including:
The temperature of the glass substrate during undercoat layer formation is preferably 500°C or higher, more preferably 600°C or higher, and even more preferably 700°C or higher, from the viewpoint of improving the reaction rate of the CVD method. Moreover, the temperature of the glass substrate is more preferably 800° C. or lower, and even more preferably 760° C. or lower, from the viewpoint of softening the glass.

As the gaseous raw material, known raw materials can be used depending on the composition of the undercoat layer. For a layer containing SiO ₂ as a main component, the gaseous raw material may be, for example, a mixed gas containing a silicon-containing substance such as silanes and an oxidizing agent such as oxygen. Further, in a layer containing SiOC as a main component, the gaseous raw material can be, for example, a mixed gas containing a silicon-containing substance such as silanes, an oxidizing agent such as carbon dioxide, and an unsaturated hydrocarbon such as ethylene. The layer mainly composed of SnO ₂ or the layer mainly composed of TiO ₂ also contains a Sn-containing substance such as monobutyltin trichloride or a Ti-containing substance such as tetraisopropoxytitanium, and further contains an oxidizing agent etc. as appropriate. The mixed gas contained can be used as a gaseous raw material.

Further, as a method for forming a transparent conductive film by CVD method, for example, a glass substrate heated to a temperature of 500 to 700° C. is reacted with a gaseous raw material to form the above-mentioned transparent conductive film on the glass substrate. Preferred is a method that includes.
The temperature of the glass substrate during the formation of the transparent conductive film is preferably 500°C or higher, more preferably 550°C or higher, from the viewpoint of improving the reaction rate of the CVD method. Moreover, the temperature of the glass substrate is more preferably 760° C. or lower, and even more preferably 730° C. or lower, from the viewpoint of glass softening.

Here, in the transparent conductive film, a method for adjusting the carrier concentration and the amount of fluorine ions to satisfy the formula 2 includes adjusting the types and mixing ratio of raw materials when forming the transparent conductive film. When forming a transparent conductive film by the CVD method, the gaseous raw material is preferably a mixed gas containing, for example, a Sn-containing substance, an F-containing substance, water (steam), and oxygen. It is also preferable that the mixed gas further contains an inert gas such as nitrogen gas.
Examples of the method for obtaining the mixed gas include a method in which each substance is supplied in a liquid or gas phase to a mixer, and mixed therein while being heated and vaporized.

Sn-containing substances include monobutyltin trichloride, tin tetrachloride, trimethyltin chloride, dimethyltin chloride, monomethyltin chloride, monobutyltin chloride, tetrabutyltin, etc. From this point of view, monobutyltin trichloride and tetrabutyltin are preferred.
Examples of the F-containing substance include hydrogen fluoride and trifluoroacetic acid, and hydrogen fluoride is preferable from the viewpoint of ease of use in a vaporizer.

At this time, the molar ratio of F to Sn in the mixed gas is preferably 0.5 or less, more preferably 0.45 or less, from the viewpoint of suppressing the amount of fluorine taken in and suppressing the excessive amount of fluorine atoms in the transparent conductive film. More preferably, it is 0.4 or less. Moreover, from the viewpoint of ensuring conductivity, the molar ratio of F is preferably 0.2 or more, more preferably 0.25 or more, and even more preferably 0.3 or more.

Moreover, the molar ratio of O ₂ to Sn in the mixed gas is preferably 4 or more, more preferably 6 or more, and even more preferably 10 or more from the viewpoint of sufficiently advancing the oxidation reaction of the raw material. The molar ratio of O ₂ is preferably 30 or less, more preferably 20 or less, and even more preferably 15 or less from the viewpoint of preventing a decrease in film forming rate due to dilution of the raw material concentration.

The molar ratio of H ₂ O to Sn in the mixed gas is preferably 10 or more, more preferably 20 or more, and even more preferably 30 or more, from the viewpoint of sufficiently advancing the hydrolysis reaction of the raw material. The molar ratio of H ₂ O is preferably 100 or less, more preferably 50 or less, and even more preferably 40 or less, from the viewpoint of preventing a decrease in the film forming rate due to dilution of the raw material concentration.

Furthermore, when the thickness of the transparent conductive film is the same, the transparent conductive film tends to easily satisfy Expression 2 by making the molar ratio of H ₂ O to Sn in the mixed gas relatively small. The reason for this tendency is not clear, but since the amount of H ₂ O in the mixed gas affects the film formation rate and the formation of grain structure, the amount of H ₂ O in the mixed gas depends on the film formation conditions. It is thought that if the fluorine content is changed, the amount of fluorine uptake tends to change greatly depending on the conditions.

Further, when the composition of the mixed gas is the same, the transparent conductive film tends to easily satisfy Expression 2 by making the thickness of the transparent conductive film relatively large.
When the molar ratio of H ₂ O to Sn is the same, by making the molar ratio of F to Sn relatively small and increasing the thickness of the transparent conductive film, the transparent conductive film tends to satisfy formula 2. There is.

Therefore, by adjusting the composition of the mixed gas to the above-mentioned preferred range and further adjusting the composition of the mixed gas and the thickness of the transparent conductive film according to the above-mentioned tendency, the relationship between the carrier concentration and the amount of fluorine ions can be improved. A transparent conductive film satisfying Formula 2 is obtained. Moreover, by manufacturing a transparent conductive film under such conditions, a transparent conductive film having a resistance change ratio of 2 or less can be obtained.

<Transparent electrode substrate for solar cells>
The glass substrate with a transparent conductive film according to this embodiment is suitably used as a transparent electrode substrate for solar cells. Preferred embodiments of the glass substrate with a transparent conductive film included in the transparent electrode substrate are the same as those described above, but the transparent electrode substrate may further have a surface layer on the transparent conductive film. Note that even in the case where a surface layer is further provided on the transparent conductive film, it is considered that the dominant factor in the heat resistance of the transparent electrode substrate is the heat resistance of the transparent conductive film. A transparent electrode substrate including such a glass substrate with a transparent conductive film is considered to have excellent heat resistance due to the same effect as the glass substrate with a transparent conductive film according to this embodiment.

(Surface layer)
The surface layer has the function of isolating electrical short-circuit points from the surroundings when the transparent electrode substrate is used as a solar cell. From the viewpoint of obtaining this effect, it is preferable that the surface layer has high resistance. Therefore, the surface layer is preferably a layer that does not contain a dopant. Further, it is preferable that the surface layer sufficiently covers the transparent conductive film.

The surface layer is not particularly limited as long as it has translucency as a transparent electrode substrate and has a certain level of conductivity, but for example, one or more layers selected from the group consisting of Sn, Zn, Ti, Cd, Mg, and In. It is preferable that the main component is an oxide of an element. Here, the main component of the surface layer means 50% by weight or more of the components constituting the surface layer, preferably 70% by weight or more, and 85% by weight or more based on the entire surface layer. It is more preferable that Moreover, the upper limit of the content as a main component is not particularly limited, and may be 100% by weight. The main component of the surface layer is more preferably SnO ₂ or ZnO, and even more preferably SnO ₂ . The composition of the surface layer can be identified by X-ray photoelectron spectroscopy (XPS) or secondary ion mass spectrometry (SIMS).

The thickness of the surface layer is preferably 80 nm or less, more preferably 60 nm or less, because if it is too thick, the resistance increases and there is a risk of interfering with electron transfer, which is a function of the electrode. On the other hand, from the viewpoint of sufficiently covering the surface of the transparent conductive film, the thickness of the surface layer is preferably 10 nm or more, more preferably 20 nm or more. The thickness of the surface layer can be measured using a stylus step meter, a fluorescent X-ray spectrometer, X-ray photoelectron spectroscopy (XPS), or secondary ion mass spectrometry (SIMS).
Further, the surface layer can be formed, for example, by the same method as the undercoat layer and transparent conductive film described above.

<Solar cells>
An example of a preferred embodiment of a solar cell having the above-described transparent electrode substrate for a solar cell will be described. The configuration and preferred embodiments of the transparent electrode substrate for solar cells are the same as those described in <Transparent electrode substrate for solar cells> above.
As the solar cell, a type of solar cell (superstrate solar cell) in which a transparent conductive film, a power generation layer (battery layer), and a back electrode are sequentially formed on a transparent substrate and sunlight enters from the transparent substrate side is preferable. Further, it is preferable to apply the transparent electrode substrate including the glass substrate with a transparent conductive film according to the present embodiment to a solar cell, such as a CdTe solar cell, in which the glass substrate with a transparent conductive film can be heated at a high temperature in the manufacturing process. However, this does not preclude application to other solar cells.
For example, as shown in FIG. 5, a CdTe solar cell has a transparent electrode substrate in which a surface layer 21 is laminated on a glass substrate with a transparent conductive film, and on the surface thereof, an n-type layer 40, a p-type layer 50, and It has a structure in which back electrodes (anodes) 60 are laminated in order.

In the case of a CdTe solar cell, a conventionally known n-type layer can be used, such as CdS, CdSe, etc.
The thickness of the n-type layer is preferably 30 nm or more, and preferably 100 nm or less.
The n-type layer can be formed by, for example, a proximity sublimation method, and its thickness and film quality can be adjusted by changing the sublimation rate or changing the substrate temperature.

CdTe is generally used as the p-type layer. The thickness of the p-type layer is preferably 3 μm or more, and preferably 15 μm or less.
The p-type layer can be formed by, for example, a proximity sublimation method, and its thickness and film quality can be adjusted by changing the sublimation rate or changing the substrate temperature.

The back electrode acts as an anode. As the back electrode, conventionally known ones can be used, such as an electrode having a structure in which films of metal materials such as silver (Ag) and molybdenum (Mo) are laminated, a carbon electrode doped with Cu, and the like. Further, a back plate glass may be further provided on the back electrode. The back plate glass only needs to have water resistance and oxygen permeability, and a back film made of resin may be used instead of the back plate glass.
The back electrode and the back glass or back film are bonded by resin encapsulation or adhesive resin.
The thickness of the back electrode is preferably 100 nm or more, and preferably 1000 nm or less. The thickness of the back plate glass or back film is preferably 1 mm or more, and preferably 3 mm or less.

The ends of the p-type layer made of CdTe or the ends of the CdTe solar cell may be sealed. Examples of the sealing material include glass having the same composition as the glass substrate in the glass substrate with a transparent conductive film, glass having other compositions, resin, and the like.

<Low emissivity glass>
The glass substrate with a transparent conductive film of this embodiment is suitably used for low emissivity glass. The configuration and preferred embodiments of the glass substrate with a transparent conductive film are the same as those described in <Glass substrate with a transparent conductive film> above.

In low emissivity glass, the emissivity value of the transparent conductive film is preferably 0.25 or less, more preferably 0.20 or less. Furthermore, the lower the emissivity of the transparent conductive film is, the more preferable it is, but it is practical to have an emissivity of 0.05 or more.

The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto. Examples 1 to 4 are examples, and Examples 5 to 8 are comparative examples.

[Examples, comparative examples]
As shown below, a glass substrate with a transparent conductive film is formed by sequentially forming an undercoat layer and a transparent conductive film using an off-line atmospheric pressure CVD (chemical vapor deposition) method that forms a film on a glass substrate shaped into a plate glass. Obtained. The glass substrate with a transparent conductive film of the present invention is not limited to one that is formed by an offline atmospheric pressure CVD method, but also one that is formed by an online atmospheric pressure CVD method in which a film is formed at the same time as the glass substrate is manufactured by a float method. A similar effect can be obtained.

A glass substrate with a transparent conductive film was manufactured using an off-line CVD apparatus of a type in which a plurality of gas supply devices were attached to a tunnel-type heating furnace in which a substrate (glass substrate) was transported by a mesh belt. Specifically, as shown below, on a glass substrate, a titanium oxide (TiO ₂ ) layer and a silicon oxide (SiO ₂ ) layer are formed as an undercoat layer, and a tin oxide layer doped with fluorine is formed as a transparent conductive film. (SnO ₂ :F) was sequentially formed to obtain a glass substrate with a transparent conductive film.

First, the glass substrate was heated to 550° C. or higher in a heating zone while being transported. Note that a soda lime silicate glass substrate with a thickness of 3.2 mm and a size of 1400 mm x 1100 mm was used as the glass substrate.
Next, vaporized titanium tetraisopropoxy, which is the raw material for the titanium oxide layer, and nitrogen gas, which is a carrier gas, are sprayed onto the heated glass substrate by a gas supply device to oxidize the surface of the glass substrate being transported. A titanium layer was formed. Note that tetratitanium isopropoxide was placed in a bubbler tank kept at a temperature of about 100° C., bubbled with nitrogen gas to vaporize it, and transported to a gas supply device through stainless steel piping.

Next, the glass substrate with the titanium oxide layer formed on its surface is heated again to 550°C or higher, and then silane gas, which is the raw material for the silicon oxide layer, oxygen gas, and nitrogen gas as a carrier gas are sprayed with a gas supply device. A silicon oxide layer was formed on the surface of the titanium oxide layer of the glass substrate being transported.

Next, after heating the glass substrate with the silicon oxide layer formed on the surface again to 550° C. or higher, a mixed gas is supplied by the gas supply device to form a transparent conductive film made of SnO ₂ :F on the SiO ₂ film. A film was formed.

[Example 1]
Here, the supply amount of each raw material in the mixed gas is shown below. In addition, for all mixed gases when forming transparent conductive films, liquid raw materials are supplied in a vaporized state to a mixer with gaseous raw materials, where they are mixed while being kept warm to form a mixed gas, which is then rectified on the surface of the glass substrate. The coating beam is then transported to the coating beam, which is supplied with gas. The mixed gas reacts on the surface of the glass substrate to form a SnO ₂ :F film, and residual gas and byproducts are exhausted. Examples 1, 2, 3, and 4 below are film forming conditions corresponding to experimental points selected from the region satisfying Equation 2 in FIG.
Mixed gas: Monobutyltin trichloride 90 g/min (liquid phase), oxygen 93 L/min (gas phase), water 86 g/min (liquid phase), hydrogen fluoride 1.4 L/min (gas phase), diluted nitrogen 246 L/min minutes

[Example 2]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows.
Mixed gas: Monobutyltin trichloride 90 g/min (liquid phase), oxygen 86 L/min (gas phase), water 113 g/min (liquid phase), hydrogen fluoride 3.6 L/min (gas phase), diluted nitrogen 266 L/min minutes

[Example 3]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows.
Mixed gas: Monobutyltin trichloride 70 g/min (liquid phase), oxygen 67 L/min (gas phase), water 134 g/min (liquid phase), hydrogen fluoride 2.2 L/min (gas phase), diluted nitrogen 297 L/min minutes

[Example 4]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows. The manufacturing conditions for the glass substrate with a transparent conductive film in Example 4 are substantially the same as in Example 3.
Mixed gas: Monobutyltin trichloride 70 g/min (liquid phase), oxygen 67 L/min (gas phase), water 134 g/min (liquid phase), hydrogen fluoride 2.2 L/min (gas phase), diluted nitrogen 297 L/min minutes

[Example 5]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows. Examples 5, 6, 7, and 8 below are film forming conditions corresponding to experimental points selected from the region in which Equation 2 in FIG. 3 is not satisfied.
Mixed gas: Monobutyltin trichloride 70 g/min (liquid phase), oxygen 67 L/min (gas phase), water 89 g/min (liquid phase), hydrogen fluoride 2.8 L/min (gas phase), diluted nitrogen 266 L/min minutes

[Example 6]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows.
Mixed gas: Monobutyltin trichloride 90 g/min (liquid phase), oxygen 86 L/min (gas phase), water 115 g/min (liquid phase), hydrogen fluoride 3.6 L/min (gas phase), diluted nitrogen 266 L/min minutes

[Example 7]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows.
Mixed gas: Monobutyltin trichloride 55 g/min (liquid phase), oxygen 53 L/min (gas phase), water 105 g/min (liquid phase), hydrogen fluoride 2.6 L/min (gas phase), diluted nitrogen 324 L/min minutes

[Example 8]
A glass substrate with a transparent conductive film was obtained in the same manner as in Example 1 except that the amount of raw material supplied in the mixed gas was changed as follows.
Mixed gas: Monobutyltin trichloride 60 g/min (liquid phase), oxygen 57 L/min (gas phase), water 115 g/min (liquid phase), hydrogen fluoride 2.9 L/min (gas phase), diluted nitrogen 292 L/min minutes

The molar ratio of H ₂ O to monobutyltin trichloride (H ₂ O/MBTC), the molar ratio of hydrogen fluoride to monobutyltin trichloride (HF/MBTC), and the molar ratio of hydrogen fluoride to monobutyltin trichloride in the mixed gas used in each example. The molar ratio of O ₂ (O ₂ /MBTC) is shown in Table 1. In addition, the following measurements and evaluations were performed on each of the obtained glass substrates with transparent conductive films. The results are shown in Table 1.

(film thickness)
The thickness of the transparent conductive film was measured using a stylus-type film thickness meter (manufactured by Sloan Technology, model number Dektak3030). Note that in Examples 3 and 4, the film forming conditions of the transparent conductive film are substantially the same, but the film thicknesses of the transparent conductive film are different. This difference reflects the fact that even with the same film forming apparatus and film forming conditions, the film thicknesses may not be the same.

(resistance change ratio)
The glass substrate with the transparent conductive film was cut into 1 cm square pieces, and using a Hall effect measuring device (manufactured by Accent Optical Technologies, HL5500PC), the sheet resistance value (initial Rs) of the transparent conductive film before the heat resistance test was measured. , specific resistance, carrier concentration, and mobility were measured. Next, a conveyor belt conveyor furnace (manufactured by DENKO) was set at 700° C., and heated for 116 minutes while being conveyed at a speed of 11.2 mm/min. Note that nitrogen was continuously supplied into the furnace to maintain an atmosphere with an oxygen concentration of 10 ppm or less. After heating, the sheet resistance value (after the Rs test) of the transparent conductive film after the heat resistance test was measured again in the same manner as described above, and the resistance change ratio was determined from the results using the following formula 1.
(Formula 1) Resistance change ratio = (sheet resistance value of transparent conductive film after heat resistance test) / (sheet resistance value of transparent conductive film before heat resistance test)

(carrier concentration, mobility)
A glass substrate with a transparent conductive film was cut into 1 cm square pieces, and the carrier concentration and mobility of the transparent conductive film were measured using a Hall effect measuring device (HL5500PC, manufactured by Accent Optical Technologies), as described above, before the heat resistance test, that is, at the initial stage. It is a measurement of the state.

(XRF F/Sn, fluorine concentration)
The fluorine concentration of the transparent conductive film was measured using a fluorescent X-ray analyzer RIX3000 (manufactured by Rigaku Co., Ltd.). The conditions were that an Rh target was used in the X-ray tube, the output was 40 kV-70 mA, and the measurement diameter was 30 mmφ. The energy positions of the fluorescent X-rays are Sn-Lα ray: 3.444 keV and F-Kα ray: 0.677 keV, and each signal intensity is a value obtained by integrating the signal intensity in the depth direction of the film thickness. The signal intensity is highest at the surface and attenuates in the depth direction of the film thickness. The signal intensity that can be detected from the film thickness depth x attenuates according to an exponential function as shown in the following equation.
Signal intensity of element a from film thickness depth x = I ₀ × exp (-x/λa) × C ₀
(I ₀ : incident X-ray intensity, C ₀ : concentration of element a in the film, λa : attenuation coefficient of element a in the film)

The fluorescent X-ray signal intensity corresponds to the value obtained by integrating the value of this equation with respect to the film thickness depth x. In determining the concentrations C ₀ of each of F and Sn in the film from the measured values, a sample quantitatively analyzed by SIMS (secondary ion mass spectrometry) was used as a standard sample. Further, for the attenuation coefficients of F and Sn, values obtained from separate studies were used.
Table 1 shows the ratio of the F signal intensity to the Sn signal intensity (XRF F/Sn) and the fluorine concentration values of the transparent conductive film obtained by the above measurements.

(Fluorine ion amount)
Using the fluorine concentration obtained above, the amount of fluorine ions per 1 cm ⁻³ of the transparent conductive film was calculated using the following formula.
Amount of fluorine ions (cm ⁻³ ) = (fluorine concentration (weight%)/100) × (density of transparent conductive film (g/cm ³ )) ÷ 18.988 × 6.022 × 10 ²³
Here, since the transparent conductive films in each example were all fluorine-doped SnO ₂ films, the density of the transparent conductive films was 6.95 g/cm ³ . Further, the atomic weight of F was 18.998, and Avogadro's number was 6.022×10 ²³ .
Table 1 shows the amount of fluorine ions ("(1)" in the table) in each glass substrate with a transparent conductive film obtained, and the value obtained by substituting the amount of fluorine ions into the right-hand side of Equation 2 below ("(1)" in the table). 2)").
(Formula 2) Carrier concentration (cm ^-3 ) > 0.45 x amount of fluorine ions (cm ^-3 ) + 1.5 x 10 ²⁰

As shown in Table 1, the glass substrates with transparent conductive films of Examples 1 to 4 had a resistance change of less than 2 and had excellent heat resistance. Further, in Examples 1 to 4, the value of (2) was smaller than the carrier concentration, and the relationship between the carrier concentration and the amount of fluorine ions satisfied Equation 2 in all examples. On the other hand, in Examples 5 to 8, which are comparative examples, the resistance change ratio was greater than 3. Further, in Examples 5 to 8, the value of (2) exceeded the initial carrier concentration, and the relationship between the carrier concentration and the amount of fluorine ions did not satisfy Equation 2 in any of the examples.

The glass substrate with a transparent conductive film according to the present invention has excellent heat resistance at high temperatures of, for example, 650°C to 700°C, so it has a low emissivity and is used for glass windows of buildings, vehicles, etc., frozen showcases, cooking utensils, etc. It is suitably used for glass and transparent electrode substrates used in solar cells. As the solar cell, for example, a superstrate type solar cell is preferable, and a solar cell in which a glass substrate with a transparent conductive film can be heated at a high temperature in the manufacturing process, such as a CdTe solar cell, is particularly preferable.

1 Glass substrate with transparent conductive film 2 CdTe solar cell 10 Glass substrate 20 Transparent conductive film 21 Surface layer 30 Undercoat layer 40 N-type layer 50 P-type layer 60 Back electrode

Claims (4)

A glass substrate with a transparent conductive film comprising a glass substrate, an undercoat layer and a transparent conductive film in this order,
The undercoat layer includes a layer containing silicon oxide as a main component,
The main component of the transparent conductive film is _SnO2 ,
The transparent conductive film contains fluorine atoms as a dopant,
The free electron mobility in the transparent conductive film is 32 cm ² /Vs or more,
The relationship between the carrier concentration of the transparent conductive film and the amount of fluorine ions per 1 cm ³ of the transparent conductive film satisfies the following formula 2,
A glass substrate with a transparent conductive film, wherein the carrier concentration is 2.0×10 ²⁰ cm ⁻³ or more.
(Formula 2) Carrier concentration (cm ^-3 ) > 0.45 x amount of fluorine ions (cm ^-3 ) + 1.5 x 10 ²⁰ The glass substrate with a transparent conductive film according to claim 1, wherein the free electron mobility in the transparent conductive film is 38 cm ² /Vs or more. The glass substrate with a transparent conductive film according to claim 1 or 2, wherein the undercoat layer has the following configuration (a) or (b).
(a) A structure in which a layer containing SiO ₂ as a main component and a layer containing TiO ₂ or SnO ₂ as a main component are laminated.
(b) A structure consisting of a layer mainly composed of SiOC or SiON. The transparent conductive film according to any one of claims 1 to 3, comprising sequentially forming the undercoat layer and the transparent conductive film on the glass substrate by a CVD (Chemical Vapor Deposition) method. A method for manufacturing a glass substrate with a film.

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