Barium silicide-based laminated substrate

Abstract

To provide a barium silicified membrane using an inexpensive board, and excellent in spectral sensitivity suitable for a solar cell absorption layer; and to provide a production method thereof.SOLUTION: A barium silicified laminated board has a barium silicified membrane and a conductive layer on a board. In the barium silicified laminated board, the conductive layer exists between the barium silicified membrane and the board, and in an X-ray diffraction test, the barium silicified membrane contains a crystal phase having a plurality of peaks belonging to an orthorhombic crystal structure. A production method thereof is also provided.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a barium silicide-based laminated substrate having excellent spectral sensitivity and a method for manufacturing the same.

Background Art

[0002] Wide bandgap semiconductors containing silicon exhibit very specific properties and are thus widely used in environmental and energy fields such as solar cell materials and thermoelectric conversion materials. Among them, barium silicide-based compounds composed of barium (Ba) and silicon (Si) have a bandgap of 1.3 eV in the BaSi 2 composition, which is larger than 1.1 eV of Si and has attracted attention (Non-Patent Document 1). Furthermore, by adding Sr, the bandgap can be adjusted up to 1.4 eV (Patent Document 1). As a usage form of barium silicide-based compounds, it is effective to use them as a film. Patent Document 2 gives an example of a solar cell in which an n-type and an n+-type barium silicide film are laminated.

[0003] As a method for manufacturing such a barium silicide-based film, a method of forming a film on a silicon (111) substrate by MBE (molecular beam epitaxy) is known. According to this film formation method, film formation with controlled composition of each element is possible, but further improvement in performance is still required, and uniform film formation over a large area is difficult, presenting problems for industrial mass production. Therefore, there is a need for a film formation technology by sputtering that enables uniform film formation over a large area, precise control of each element, and a high film formation rate.

[0004] Regarding the sputtering method, the present inventors have disclosed a barium silicide polycrystal with high density and no cracks and a sputtering target using the same in Patent Document 3. However, there is little research on barium silicide-based films, and although there are some examples cited in Non-Patent Document 2, research on further improving the characteristics of solar cells and the like has not progressed.

[0005] In addition, in order to form a solar cell structure, electrodes are required above and below the barium silicide, so it was necessary to use a conductive substrate such as silicon as the substrate. Patent Document 4 describes that the spectral characteristics are improved by adding hydrogen, but higher spectral characteristics are required.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0007]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a barium silicide-based laminated substrate having excellent spectral sensitivity and a method for manufacturing the same.

Means for Solving the Problems

[0009] In view of the above background, as a result of intensive studies, the present inventors have found a barium silicide-based laminated substrate having excellent spectral sensitivity and a method for manufacturing the same, and have completed the present invention.

[0010] That is, aspects of the present invention are as follows. (1) A barium silicide-based laminated substrate having a barium silicide film layer and a conductive layer on a substrate, wherein a conductive layer exists between the barium silicide film layer and the substrate, and the barium silicide film layer contains a crystal phase having a plurality of peaks attributed to an orthorhombic crystal structure in an X-ray diffraction test. A barium silicide-based laminated substrate characterized by this. (2) The barium silicide-based laminated substrate according to (1) above, wherein the conductive layer is a non-oxide. (3) The barium silicide-based laminated substrate according to (1) or (2) above, wherein the conductive layer is a nitride. (4) The barium silicide-based laminated substrate according to any one of (1) to (3) above, wherein the conductive layer is titanium nitride. (5) The barium silicide-based laminated substrate according to any one of (1) to (4) above, wherein the titanium nitride does not include crystal orientations of (200) and (222).

[0011] (6) The barium silicide-based laminated substrate according to any one of (1) to (5) above, wherein the crystal phase contained in the barium silicide film layer has not only an integer multiple of a specific orientation but also three or more other peaks. (7) In the X-ray diffraction test of the barium silicide film layer, for the peak attributed to the orthorhombic crystal structure, the height of the peak detected near 32 degrees is smaller than the height of the peak near 25 degrees. The barium silicide-based laminated substrate according to any one of (1) to (6) above. (8) In the Raman spectrum of the barium silicide film layer, for the A g peak, the peak intensity ratio attributed to 503 cm -1 is less than 10%. The barium silicide-based laminated substrate according to any one of (1) to (7) above. (9) In the Raman spectrum of the barium silicide film layer, for the A g peak, the peak intensity ratio attributed to 250 cm -1 is less than 10%. The barium silicide-based laminated substrate according to any one of (1) to (8) above. (10) The barium silicide-based laminated substrate according to any one of (1) to (9) above, having a cap layer on the surface of the barium silicide film layer.

[0012] (11) The barium silicide-based laminated substrate according to any one of (1) to (10) above, wherein the cap layer is a metal silicon film. (12) The barium silicide-based laminated substrate according to any one of (1) to (11) above, wherein the substrate is a silicon substrate or a glass-based substrate. (13) A solar cell element using the barium silicide-based laminated substrate according to any one of (1) to (12) above. (14) A method for manufacturing the barium silicide-based laminated substrate according to any one of (1) to (12) above, comprising forming a conductive layer on a substrate and then forming a barium silicide-based film on the conductive layer. (15) The manufacturing method according to (14) above, wherein both the method of forming a conductive layer on a substrate and the method of forming a barium silicide-based film on the conductive layer are film-forming methods by sputtering. (16) The manufacturing method according to (14) or (15) above, wherein the conductive layer is titanium nitride and the film is formed by sputtering at a temperature of 20 ° C or higher and lower than 200 ° C.

Effect of the Invention

[0013] According to the present invention, a barium silicide-based laminated substrate excellent in spectral sensitivity suitable for the absorption layer of a solar cell is provided.

Brief Description of the Drawings

[0014]

Figure 1

Embodiments for Carrying Out the Invention

[0015] <Barium Silicide-Based Laminated Substrate> The barium silicide-based laminated substrate of the present invention is characterized in that a conductive layer exists between the barium silicide-based film and the substrate, and the barium silicide-based film contains a crystal phase having a plurality of peaks attributed to an orthorhombic crystal structure in an X-ray diffraction test. By using a barium silicide-based laminated substrate, it becomes possible to extract electricity by utilizing the conductive layer portion, and even if the substrate is insulating, it can be made into a solar cell.

[0016] (Conductive layer) The conductive layer is a material with low reactivity with barium silicide and various substrates, and since it is preferable that oxygen does not diffuse into barium silicide, non-oxides are preferable. Examples of such non-oxides include nitrides such as tungsten nitride, tantalum nitride, titanium nitride, and titanium aluminum nitride, and silicides such as calcium silicide and ruthenium silicide. Among them, nitrides are preferable, more preferably tungsten nitride, tantalum nitride, titanium nitride, titanium aluminum nitride, etc., and particularly preferably titanium nitride.

[0017] Furthermore, as will be described later, the material of the conductive layer requires a high temperature to obtain a crystalline film of barium silicide. At high temperatures, silicon atoms easily form various compounds and silicides, so it is necessary to select a material that does not form silicides. For example, in the case of an oxide conductive layer, oxygen may diffuse during heat deposition. Also, when using a metal as the conductive film, most metals form silicides with silicon, so it is difficult to use them as the conductive layer.

[0018] The film thickness of the conductive layer is preferably 10 nm to 500 nm, more preferably 20 nm to 300 nm. By doing so, it is possible to suppress the diffusion of elements from the substrate during heating and exhibit high electrical conductivity. When the conductive layer is titanium nitride, its crystal orientation preferably does not include (200) and (222). The appearance of these crystal orientations increases surface unevenness and makes it impossible to suppress the diffusion of elements in the substrate portion. By doing so, it becomes possible to use various substrates.

[0019] (Barium silicide-based film) The barium silicide film layer preferably has multiple peaks attributable to an orthorhombic crystal structure in an X-ray diffraction test. By forming a barium silicide film layer having such a crystal phase, since it has polycrystallinity, the durability of the film is high, the film characteristics are excellent, and a highly stable film can be obtained. The crystal phase preferably has not only integral multiples of a specific orientation but also three or more peaks in other orientations, more preferably five or more, and even more preferably ten or more. Note that peaks attributable to the conductive film formed as the base are excluded.

[0020] In addition, in the X-ray diffraction test of the barium silicide film layer, the peak attributable to the orthorhombic crystal structure preferably has a small peak detected around 32 degrees. The peak height is preferably lower than the peak intensities of the (211) plane and (103) plane of BaSi at around 25 degrees. The peak around 32 degrees may be of other crystal phases, particularly Ba 2 Si 8 Si 46 (Card No01-070-3706) or Ba 6 Si 25 (Card No01-070-4268), and when these crystal phases precipitate, the spectral characteristics deteriorate.

[0021] In the X-ray diffraction test, the fact that it is composed of multiple peaks attributable to the orthorhombic crystal structure can be confirmed as follows. That is, the peak attributable to the orthorhombic crystal structure means that the diffraction peak detected within the range of 2θ = 20 to 80° of X-rays with Cu as the radiation source can be indexed to the peak pattern attributable to JCPDS (Joint Committee for Powder Diffraction Standards) Card No. 01-071-2327 or a peak pattern similar thereto (shifted peak pattern).

[0022] The barium silicide film layer is preferably a polycrystalline film. By forming a polycrystalline film, the stability of film characteristics such as the strength of the film and the reduction of the distribution of spectral characteristics in the film is improved compared to a single crystal. The barium silicide film has a peak intensity ratio for the A peak at 503 cm g in the Raman spectrum of less than 10%, more preferably 2% or less, and even more preferably 0.5% or less. In the Raman spectrum, the presence of a peak at 503 cm -1 indicates that the barium silicide has been oxidized and barium silicate or the like has been formed. This is presumably due to partial oxidation, and the presence of the peak at 503 cm -1 has an adverse effect on the spectral sensitivity. By reducing the silicate layer that is the cause of this, crystal defects can be reduced and the spectral characteristics can be improved.

[0023] Also, the barium silicide film preferably has a peak intensity ratio for the A peak at 250 cm g in the Raman spectrum of less than 10%, more preferably 2% or less, and even more preferably 0.5% or less. In the Raman spectrum, the presence of a peak at 250 cm -1 indicates that a crystal phase other than barium silicide BaSi -1 has been formed, which has an adverse effect on the spectral characteristics.

[0024] The barium silicide film preferably has an atomic weight ratio of silicon to barium Si / Ba contained therein of 1.8 to 2.1, and particularly preferably 1.9 to 2.0.

[0025] The barium silicide film may contain a carbon content of 1×10 18 atms / cm 3 to 1×10 21 atms / cm 3 . Preferably it is 3×10 18 atms / cm 3 to 1×10 20 atms / cm 3 , and even more preferably 5×10 18 atms / cm 3 to 5×10 19 atms / cm 3 . g peak at 503 cm -1 preferably less than 10%, more preferably 2% or less, and even more preferably 0.5% or less. In the Raman spectrum, the presence of a peak at 503 cm -1 -1 represents that the barium silicide has been oxidized and barium silicate or the like has been formed. This is presumably due to partial oxidation, and the presence of the peak at 503 cm -1 -1 has an adverse effect on the spectral sensitivity. By reducing the silicate layer that is the cause of this, crystal defects can be reduced and the spectral characteristics can be improved. g peak at 250 cm -1 preferably less than 10%, more preferably 2% or less, and even more preferably 0.5% or less. In the Raman spectrum, the presence of a peak at 250 cm -1 -1 indicates that a crystal phase other than barium silicide BaSi 2 2 has been formed, which has an adverse effect on the spectral characteristics. 18 atms / cm 3 to 1×10 21 atms / cm 3 Preferably it is 3×10 18 18 atms / cm 3 to 1×10 20 atms / cm 3 and even more preferably 5×10 18 18 atms / cm 3 to 5×10 19 atms / cm 3It is as follows. By containing carbon within this range, the spectroscopic characteristics resulting from the crystal defects in the barium silicide-based film can be significantly improved. If a large amount of carbon is contained, it interferes with parts other than the crystal defects, deteriorates the crystallinity of the film, and worsens the spectroscopic characteristics of the film. Also, when the carbon content is low, a decrease in spectroscopic sensitivity occurs due to lattice defects present in the film.

[0026] The carbon content in the barium silicide-based film can be determined by measurement using SIMS (Secondary Ion Mass Spectrometry). The carbon content is defined as the amount of carbon present in the layer with a thickness of 100 nm, excluding the 100-nm-thick surface layer from the side opposite to the substrate side of the film at a film thickness of 300 nm. This is because the surface layer is affected by surface oxidation and unevenness and may not necessarily represent the carbon amount of the film body.

[0027] Furthermore, the barium silicide-based film preferably has an oxygen content of 10 atm% or less, more preferably 5 atm% or less, and even more preferably 3 atm% or less. Introducing oxygen reduces the influence of crystal defects, but if a large amount of oxygen is present, oxygen and hydrogen in the film react, and when present as moisture in the barium silicide-based film, barium silicide changes to silicate, deteriorating the film characteristics. The oxygen content is preferably 0.01 atm% or more, and more preferably 0.1 atm% or more. By adjusting the oxygen amount within the above range, it is possible to obtain a preferable bandgap while maintaining crystallinity.

[0028] The measurement of the oxygen content in the barium silicide-based film can be performed using RBS (Rutherford Backscattering Spectrometry). When higher accuracy is required, SIMS is used for measurement and converted to atm%. The oxygen content is defined as the amount of oxygen present in the layer between 50 and 300 nm, excluding the 50-nm-thick surface layer of the film at a film thickness of 300 nm.

[0029] The barium silicide-based film has a hydrogen content of 1×10 18 atms / cm 3 ~1×10 21 atms / cm 3It is preferably, more preferably 3×10 18 atms / cm 3 ~1×10 20 atms / cm 3 、and particularly preferably 5×10 18 atms / cm 3 ~5×10 19 atms / cm 3 . By containing hydrogen within this range, the spectral characteristics resulting from crystal defects in the barium silicide-based film can be improved. If a large amount of hydrogen is contained, it interferes with parts other than crystal defects, deteriorates the crystallinity of the film, and worsens the spectral characteristics of the film. Also, if the hydrogen content is low, a decrease in spectral sensitivity occurs due to lattice defects present in the film.

[0030] The hydrogen content in the barium silicide-based film can be determined by measuring it by SIMS (Secondary Ion Mass Spectrometry). In the measurement, in the case of a film thickness of 300 nm, the amount of hydrogen present in the layer with a thickness of 100 nm, excluding the 100 nm thick surface layer from the side opposite to the substrate side of the film, is determined. Note that the barium silicide-based film of the present invention may contain trace amounts of impurities such as magnesium, calcium, strontium, etc. other than carbon, hydrogen, and oxygen.

[0031] The film thickness of the barium silicide-based film is preferably 50 nm to 2000 nm, more preferably 100 nm to 1000 nm, and particularly preferably 100 nm to 800 nm. The barium silicide-based film may contain other elements according to its required characteristics. For example, for making it p-type, elements of Group 13 of the periodic table such as boron (B), aluminum (Al), etc., and for making it n-type, elements of Group 15 of the periodic table such as nitrogen (N), phosphorus (P), antimony (Sb), etc. may be contained.

[0032] (Substrate) The substrate is not particularly limited, and examples thereof include silicon; glass substrates such as alkali-free glass and quartz glass; germanium; sapphire and the like. Among them, silicon and glass substrates that enable the growth of a barium silicide film system with high crystallinity at low cost are preferable, and particularly preferably, alkali-free glass that enables a large area is used. It is preferable that a cap layer exists on the surface layer of the barium silicide-based laminated substrate. By capping the surface layer, it becomes possible to suppress the progress of oxidation from the surface. The material of the layer used as the cap layer is not particularly limited, and examples thereof include silicon (crystalline, amorphous), etc. Among them, in order to suppress oxidation, it is preferably a layer that does not contain oxygen such as metallic silicon. The thickness of the cap layer is preferably 1 nm to 10 nm, and more preferably 1 nm to 5 nm.

[0033] <Method for manufacturing a barium silicide-based laminated substrate> The barium silicide-based laminated substrate of the present invention can be manufactured, for example, by forming a conductive layer on a substrate and then forming a barium silicide film system on the conductive layer.

[0034] (Method for forming a conductive layer) The method for forming the conductive layer is not particularly limited, but various methods such as a sputtering method using a sputtering target, an MBE (molecular beam epitaxy) method, and a chemical vapor deposition method are selected according to the barium silicide film system described later. Among them, the conductive layer is preferably a film formed by the MBE method or the sputtering method, and particularly preferably a film formed by the sputtering method.

[0035] As the sputtering method, a DC sputtering method, an RF sputtering method, an AC sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, an ion beam sputtering method, etc. can be appropriately selected. Among these, the DC magnetron sputtering method or the RF magnetron sputtering method is more preferable in terms of being able to form a uniform film over a large area at high speed, and the DC magnetron sputtering method is even more preferable.

[0036] For the target in sputtering, it is preferable to use various nitride targets and metal targets. By doing so, it is possible to suppress the incorporation of other elements. However, in order to suppress the alteration of the target surface, etc., it is preferable to use a nitride target.

[0037] As the sputtering method, sputtering using a nitride target and argon or xenon gas, or reactive sputtering containing nitrogen gas, or reactive sputtering using a metal target is preferable. Among them, sputtering containing nitrogen gas using a nitride target is preferable. By doing so, it becomes possible to stably form a nitride film.

[0038] In the sputtering method, when forming a titanium nitride film, the temperature during film formation is preferably 20°C or higher and less than 200°C, more preferably 20°C or higher and 170°C or lower, and even more preferably 20°C or higher and 160°C or lower. By setting the range, the surface unevenness of the titanium nitride layer can be suppressed, and a high-quality film can be grown. If it is outside the range, the unevenness increases, and other crystal phases precipitate, resulting in an unstable film structure and deterioration of the spectroscopic characteristics of the barium silicide layer.

[0039] (Method for forming a barium silicide film) The barium silicide film can be manufactured by various methods such as a sputtering method using a sputtering target, an MBE (Molecular Beam Epitaxy) method, a chemical vapor deposition method, etc. Among them, it is preferably a film formed by the MBE method or the sputtering method, and particularly preferably a film formed by the sputtering method. And among the sputtering methods, in the Raman spectrum, the peak intensity ratio of the Si phonon to the A peak is less than 10%, and it is preferably a film formed by the sputtering method. g phonon to the A TO phonon peak intensity ratio is less than 10%, and it is preferably a film formed by the sputtering method.

[0040] As the sputtering method, a DC sputtering method, an RF sputtering method, an AC sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, an ion beam sputtering method, etc. can be appropriately selected. Among these, the DC magnetron sputtering method or the RF magnetron sputtering method is more preferable in terms of being able to form a film uniformly over a large area and at high speed, and particularly preferably the RF magnetron sputtering method.

[0041] The temperature during sputtering is not particularly limited. In order to improve crystallinity, 400 °C or higher is preferable, more preferably 500 °C to 800 °C, and particularly preferably 580 °C to 650 °C. At temperatures higher than that, the materials used for the apparatus become expensive. As the atmosphere gas during sputtering, usually, an inert gas such as argon gas, nitrogen gas, etc. is used.

[0042] The introduction of carbon into the barium silicide film can be carried out during the film formation of the barium silicide film. There is no particular limitation on the method of introducing carbon, and it is preferable to use a target containing carbon and a barium silicide target in combination during sputtering. However, in order to avoid unnecessary elements, the target containing carbon is preferably a target of a compound such as carbon, silicon carbide, barium carbide, etc.

[0043] The introduction of oxygen into the barium silicide film is carried out by introducing oxygen during or after the formation of a good barium silicide film. There are no particular limitations on the introduction of hydrogen. In order to act more on the defective part, it is preferable to use active hydrogen, and examples include the introduction of active hydrogen by an RF plasma gun and the method of introducing hydrogen into the sputtering gas. When using an RF plasma gun, it is possible to control the amount of hydrogen in the film according to the irradiation time. The irradiation time is preferably 1 minute to 60 minutes, more preferably 5 minutes to 40 minutes, and particularly preferably 15 minutes to 30 minutes. By setting it within this range, it is possible to introduce a preferable amount of active hydrogen into the film.

[0044] In addition, the same effect can also be achieved by activating the hydrogen present in the film after film formation. For example, by exposing the barium silicide-based film in plasma after film formation, the hydrogen in the film is activated, and it is possible to suppress the deterioration of the spectral characteristics due to defects. Note that as the sputtering target used for the barium silicide-based film, barium silicides such as BaSi 2 are preferable. By using the target of the barium silicide-based material, a barium silicide-based film having excellent characteristics can be obtained by the sputtering method.

[0045] The manufacturing method of the sputtering target of the barium silicide-based material is not particularly limited. In the sputtering method for manufacturing the sputtering target of the barium silicide-based material, it is also possible to change the silicon-barium ratio by forming a film on the sputtering target of barium silicide with silicon or barium placed thereon.

[0046] The silicon-barium ratio can also be adjusted by the gas pressure during the sputtering film formation of the barium silicide layer. Since the atomic weight ratio of the orthorhombic crystal of BaSi 2 with good spectral sensitivity characteristics is 1:2, it is preferable that the composition of the film is also close to 1:2, and it is possible to make the silicon:barium ratio closer to 1:2 by increasing the sputtering gas pressure. However, simply increasing the gas pressure tends to deteriorate the crystallinity and decrease the film formation rate.

[0047] The preferable range of the gas pressure (absolute pressure) during sputtering film formation is preferably 0.1 Pa to 1.0 Pa, and more preferably 0.3 Pa to 0.8 Pa. By setting the gas pressure to this value, it becomes possible to obtain a barium silicide-based film with improved crystallinity.

[0048] The barium silicide-based film of the present invention can also be a barium silicide-based laminated film by laminating a silicon layer as a cap layer. Furthermore, for example, when assuming an absorption layer for a solar cell, a barium silicide-based film without adding a dopant, an n-type barium silicide-based film, a p-type barium silicide-based film, and a layer containing at least two or more cap layers are formed. There is no limitation on the film formation method, and various film formation methods such as physical vapor deposition and chemical vapor deposition can be used.

[0049] <Barium silicide-based laminated substrate> Since the barium silicide-based laminated substrate of the present invention is excellent in spectral sensitivity, it is particularly suitable as a light absorption element in a solar cell or a thermoelectric conversion element. Further, by using the element, light or heat can be efficiently converted into electrical energy, so it is suitable for electronic devices, particularly suitable for solar cell modules and thermoelectric conversion modules.

[0050] The spectral sensitivity is represented by A(λ) / W(λ) (A: output current, W: irradiation intensity) and is an index indicating solar cell characteristics. Also, by applying a bias voltage, it becomes possible to grasp the output current at that voltage. As an evaluation in the present invention, the spectral sensitivity (normalized) was defined by the following formula. In the formula, the bias voltage (V) represents the absolute value of the bias voltage. Spectral sensitivity (normalized) = maximum spectral sensitivity (A / W) / bias voltage (V) The higher the spectral sensitivity, the higher the extraction current at a voltage value below the open-circuit voltage, and it is expected that the solar cell conversion efficiency will be improved. The spectral sensitivity of the barium silicide-based film of the present invention can be 2.0 or more, further 3.0 or more, and particularly 4.0 or more.

Example

[0051] The present invention will be specifically described by the following examples, but the present invention is not limited to these examples. The evaluation of each characteristic was carried out as follows.

[0052] (Raman spectrum 503 cm -1 / Ag ratio) The Raman spectrum was measured using a Raman spectrometer (manufactured by JASCO Corporation, NRS-5100) under the condition of an excitation wavelength of 532 nm, and the peak near a wavelength of 480 cm -1 was defined as peak A g peak, and the peak near 503 cm -1 was defined as the peak derived from the barium silicate compound, and the ratio of the intensities of the respective peaks was calculated. Raman spectrum 503 cm -1 / Ag ratio (%) = 503 cm -1 near peak intensity / A g peak intensity In addition, the intensities of the two peaks were calculated after separation.

[0053] (X-ray diffraction test) The crystal phase of the barium silicide film was identified by an X-ray diffraction test. The measurement conditions are as follows. · X-ray source: CuKα · Power: 40 kV, 40 mA · Scanning speed: 1° / min The obtained diffraction pattern was analyzed and classified into (1) a phase composed of peaks attributed to an orthorhombic crystal structure and (2) other crystal phases other than (1). When identified in each of these crystal phases (1) and (2), it was regarded as "present", and when not identified, it was regarded as "absent".

[0054] (Spectral sensitivity) For the measurement of the spectral sensitivity of the barium silicide film, an ITO electrode with a diameter of 1 mm and a thickness of 80 nm was fabricated on the surface layer side, an Al electrode was fabricated on the back surface of the substrate, a voltage was applied between the electrodes, and then the measurement was carried out using an apparatus manufactured by Spectrometer Co., Ltd., SM-1700A.

[0055] (Examples 1 and 2) As a sputtering apparatus, an apparatus capable of binary simultaneous sputtering (manufactured by ULVAC, Inc.) whose schematic diagram is shown in Fig. 1 was used. As the target 1 for forming the conductive layer, a titanium nitride sputtering target was used, and sputtering was performed under the following conditions so that nitrogen and titanium (sputtered particles in Fig. 1) were ejected. Thereafter, as the target 2 for forming the barium silicide film, a barium silicide sputtering target was used, and a sputtering film formation test was carried out under the following conditions. A barium chip was placed on the barium silicide sputtering target, and argon was collided so that silicon elements and barium elements (sputtered particles in Fig. 1) were ejected from the barium silicide, and barium elements (sputtered particles in Fig. 1) were ejected from the barium of the chip.

[0056] As the substrate, a 25 mm square silicon (111) substrate with a thickness of 0.5 mm was used. On the silicon substrate, sputtering was performed under the following "A: Sputtering conditions for the conductive layer (titanium nitride)", and a conductive layer of titanium nitride with a thickness of 250 nm was formed. Next, on the titanium nitride film, sputtering was performed under the following "B: Sputtering conditions for the barium silicide film", and a barium silicide film with a thickness of 290 nm was formed. Furthermore, on the barium silicide film, as a cap layer, amorphous silicon was formed to a thickness of 3 nm by sputtering at 170 °C.

[0057] A. Sputtering conditions for the conductive layer (titanium nitride) Discharge method: RF sputtering Film formation apparatus: Magnetron sputtering apparatus (for binary simultaneous film formation) Distance between target and substrate: 200 mm Film formation pressure (gas pressure inside the apparatus): 0.5 Pa Introduced gas: Argon Target: Titanium nitride Target size: 50 mm φ (disk shape) Discharge power: 100 W (5.1 W / cm 2 ) Substrate temperature: 100 °C (Example 1), 150 °C (Example 2)

[0058] B. Sputtering conditions for barium silicide film Discharge method: RF sputtering Film formation apparatus: Magnetron sputtering apparatus (for dual - layer simultaneous film formation) Distance between target and substrate: 200 mm Film formation pressure (gas pressure inside the apparatus): 0.5 - 0.8 Pa Introduced gas: Argon Substrate temperature: 600 °C Film thickness: 290 nm (Example 1), 240 nm (Example 2) Target: Barium silicide (BaSi 2 ) Target size: 50 mm φ (disk shape) Barium chip size: 10 mm × 20 mm (plate shape) Number of barium chips: 2 (installed in the erosion part) Discharge power: 20 W (1 W / cm 2 )

[0059] C. Sputtering conditions for cap layer Discharge power: 50 W (1 W / cm 2 ) Substrate temperature: 170 °C Film formation pressure (gas pressure inside the apparatus): 0.7 Pa

[0060] According to Examples 1 and 2 above, a substrate with a laminated film of a barium silicide layer having a Raman spectrum as shown in Table 1 and a conductive film / barium silicide film system having a crystal phase with a plurality of peaks attributed to orthorhombic in an X - ray diffraction test was obtained.

[0061] (Example 3) As a substrate, sputtering was carried out under the same conditions as in Example 2 except that an alkali-free glass (Eagle XG manufactured by Corning) was used, and a barium silicide / titanium nitride laminated film was produced. As a result, a substrate with a laminated film having a Raman spectrum and a crystal phase as shown in Table 1, high spectral sensitivity, and high expected photoelectric conversion ability was obtained.

[0062] (Example 4) Sputtering was carried out under the same conditions as in Example 3 except that the film formation temperature of titanium nitride was room temperature (25°C), and a barium silicide / titanium nitride laminated film was produced. As a result, a substrate with a laminated film having a Raman spectrum and a crystal phase as shown in Table 1, high spectral sensitivity, and high expected photoelectric conversion ability was obtained.

[0063] (Example 5) Sputtering was carried out under the same conditions as in Example 4 except that the film formation temperature was 630°C, and a barium silicide / titanium nitride laminated film was produced. As a result, a substrate with a laminated film having a Raman spectrum and a crystal phase as shown in Table 1, high spectral sensitivity, and high expected photoelectric conversion ability was obtained.

[0064] (Comparative Examples 1 and 2) Without forming a conductive layer, using a sputtering target 2 of barium silicide, and as substrates, in Comparative Example 1, the same silicon substrate as in Example 1 was used, and in Comparative Example 2, the same alkali-free glass substrate as in Example 3 was used. Otherwise, in both cases, a film formation test by sputtering was carried out under the same conditions as in Examples 1 and 3. As a result, it has the Raman spectrum intensity ratio and spectral sensitivity shown in Table 1, and since it does not have a conductive layer, a film with excellent spectral sensitivity could not be obtained.

[0065]

Table 1

Industrial Applicability

[0066] Since the barium silicide-based laminated substrate of the present invention is excellent in spectral sensitivity, it is particularly suitable for solar cell modules and thermoelectric conversion modules.

Explanation of Signs

[0067] 1: Target 1, 2: Target 2, 3: Substrate 4: Sputtered layer 〇: Argon ●: Sputtered particles

Claims

1. A barium silicide-based laminated substrate having a barium silicide film layer and a conductive layer on a substrate, wherein a conductive layer exists between the barium silicide film layer and the substrate, the barium silicide film layer contains a crystal phase having a plurality of peaks attributed to an orthorhombic crystal structure in an X-ray diffraction test, the conductive layer is a nitride, and the substrate is a silicon substrate or a glass-based substrate. The barium silicide-based laminated substrate is characterized by this.

2. The barium silicide-based laminated substrate according to claim 1, wherein the conductive layer is titanium nitride.

3. The barium silicide-based laminated substrate according to claim 2, wherein the titanium nitride does not include crystal orientations of (200) and (222).

4. The barium silicide-based laminated substrate according to any one of claims 1 to 3, wherein the crystal phase contained in the barium silicide film layer has not only integer multiples of a specific orientation but also three or more peaks in other orientations.

5. In the X-ray diffraction test of the barium silicide film layer, for the peaks attributed to the orthorhombic crystal structure, the height of the peak detected around 32 degrees is smaller than the height of the peak around 25 degrees. The barium silicide-based laminated substrate according to any one of claims 1 to 4 is characterized by this.

6. In the Raman spectrum of the barium silicide-based film, A ｇ The peak intensity ratio attributed to the peak at 503 cm －１ is less than 10%. The barium silicide-based laminated substrate according to any one of claims 1 to 5.

7. The barium silicide-based film layer has peak intensity ratio for peak A in Raman spectrum less than 10% for the peak attributed to 250 cm ｇ The barium silicide-based laminated substrate according to any one of claims 1 to 6. －１ ​

8. The barium silicide-based laminated substrate according to any one of claims 1 to 7, which has a cap layer on the surface of the barium silicide film layer.

9. The barium silicide-based laminated substrate according to claim 8, wherein the cap layer is a metal silicon film.

10. A solar cell element using the barium silicide-based laminated substrate according to any one of claims 1 to 9.

11. A manufacturing method of the barium silicide-based laminated substrate according to any one of claims 1 to 9, which includes forming a conductive layer on a substrate and then forming a barium silicide film layer on the conductive layer.

12. The manufacturing method according to claim 11, wherein both the method of forming a conductive layer on a substrate and the method of forming a barium silicide film layer on the conductive layer are film-forming methods by sputtering.

13. The manufacturing method according to claim 12, wherein the conductive layer is titanium nitride, and it is a film-forming method by sputtering at a temperature of 20°C or higher and lower than 200°C.

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