JP2016018903A - Thermoelectric conversion material, thermoelectric conversion module and method for producing thermoelectric conversion material - Google Patents
Thermoelectric conversion material, thermoelectric conversion module and method for producing thermoelectric conversion material Download PDFInfo
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本発明は、熱電変換材料、熱電変換モジュール、熱電変換材料の製造方法に関する。 The present invention relates to a thermoelectric conversion material, a thermoelectric conversion module, and a method for manufacturing a thermoelectric conversion material.
熱電変換材料は、２種類の物質を接合させて両端に温度差を生じさせると電圧が発生するゼーベック効果が基本になっている。これまでにＢｉ2Ｔｅ3等からなる熱電変換材料が開発され、実用化されているが、希少金属や有害金属を含むことや変換効率が低いことが普及への課題となっている。 The thermoelectric conversion material is based on the Seebeck effect in which a voltage is generated when two kinds of substances are joined to cause a temperature difference between both ends. So far, thermoelectric conversion materials made of Bi 2 Te 3 and the like have been developed and put into practical use. However, the inclusion of rare metals and toxic metals and low conversion efficiency are problems for diffusion.
この変換効率を向上させるためのアプローチとして、熱電変換材料をナノサイズ化することでバルク状態の熱電変換材料に比べて変換効率が向上することが理論的に示されている。ここで、熱電変換材料の指標として一般的に使用される性能指数Ｚは以下の式（１）によって定義されている。 As an approach for improving the conversion efficiency, it has been theoretically shown that the conversion efficiency is improved by making the thermoelectric conversion material nano-sized as compared with the bulk thermoelectric conversion material. Here, the figure of merit Z generally used as an index of the thermoelectric conversion material is defined by the following formula (1).
Ｚ＝Ｓ2×σ／κ （１）
ナノサイズ化することにより性能が向上する理由は２つある。１つは、ナノサイズ化することによってフォノンを効果的に散乱することにより熱伝導率κが低減するためである。もう１つは、熱電変換材料が量子サイズまで小さくなったときに発現する量子効果によって状態密度が変化することによりゼーベック係数Ｓが向上するためである。後者は性能向上のために特に効果が大きいことが予測されているが、特性は熱電変換材料の次元数によっても変化する。例えば、２次元化した材料（超格子薄膜）よりも１次元化した材料（ナノワイヤ）の方が特性は向上することが予測されている。
Z = S 2 × σ / κ (1)
There are two reasons why the performance is improved by the nano-size. One is that the thermal conductivity κ is reduced by effectively scattering phonons by nano-sizing. The other is that the Seebeck coefficient S is improved by changing the density of states due to the quantum effect that appears when the thermoelectric conversion material is reduced to the quantum size. The latter is expected to be particularly effective for improving performance, but the characteristics also change depending on the dimensionality of the thermoelectric conversion material. For example, it is predicted that characteristics are improved in a one-dimensional material (nanowire) than in a two-dimensional material (superlattice thin film).
例えば、ガラス部材の中に熱電変換材料を充填し、その後延伸してナノワイヤ化された熱電変換材料が公開されている（特許文献１参照）。 For example, a thermoelectric conversion material in which a glass member is filled with a thermoelectric conversion material and then drawn into a nanowire is disclosed (see Patent Document 1).
しかし、特許文献１に記載の熱電変換材料は、変換効率に改良の余地がある。 However, the thermoelectric conversion material described in Patent Document 1 has room for improvement in conversion efficiency.
そこで本発明の目的は、上記問題に鑑みてなされたものであり、変換効率を向上することにある。 Accordingly, an object of the present invention has been made in view of the above problems, and is to improve conversion efficiency.
上記目的は、例えば特許請求の範囲に記載された発明により達成される。 The above object can be achieved, for example, by the invention described in the claims.
本発明によれば、変換効率を向上することができる。 According to the present invention, the conversion efficiency can be improved.
以下、本発明の実施形態について、図面を参照しながら説明する。なお、本発明はここで取り上げた実施形態に限定されることはなく、要旨を変更しない範囲で適宜組み合わせや改良が可能である。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to embodiment taken up here, A combination and improvement are possible suitably in the range which does not change a summary.
図１は、本実施形態に係る熱電変換材料の模式図である。熱電変換材料１００は、薄膜状（平板状）の熱電変換相１０２とその両面を挟む相１０１を少なくとも備え、これらは異なる相である。図では３層に薄膜が積層した場合を示すが、熱電変換相１０２とそれを挟む相１０１の少なくとも２種類の異なる相を交互に積層し、４層以上形成してもよい。また、相１０１を薄膜より厚い基板とし、この基板上に熱電変換相１０２を形成し、この熱電変換相１０２上に基板と同じ成分の相１０１を形成してもよい。熱電変換相１０２上に形成する相１０１は基板と同じ成分でなくてもよく、熱電変換相１０２中の母相１０４と異なる成分であればよい。 FIG. 1 is a schematic view of a thermoelectric conversion material according to the present embodiment. The thermoelectric conversion material 100 includes at least a thin film (flat plate) thermoelectric conversion phase 102 and a phase 101 sandwiching both surfaces thereof, which are different phases. Although the figure shows a case where thin films are laminated in three layers, at least two different phases of the thermoelectric conversion phase 102 and the phase 101 sandwiching it may be alternately laminated to form four or more layers. Alternatively, the phase 101 may be a substrate thicker than the thin film, the thermoelectric conversion phase 102 may be formed on the substrate, and the phase 101 having the same component as the substrate may be formed on the thermoelectric conversion phase 102. The phase 101 formed on the thermoelectric conversion phase 102 may not be the same component as the substrate, and may be a component different from the parent phase 104 in the thermoelectric conversion phase 102.
熱電変換相は量子井戸構造となっており、熱電変換相中には母相１０４と異なる異相１０３が存在する。ここで量子井戸構造とは、バンドギャップの小さい熱電変換相１０２がバンドギャップの大きい相１０１に挟まれることによって、電子の移動方向が束縛された構造のことを指す。このとき、熱電変換相１０２の厚みは、１０ｎｍ以下であることが望ましい。この理由は、１０ｎｍ以下になることで量子閉じ込め効果によるゼーベック係数の向上の効果が発現されるためである。 The thermoelectric conversion phase has a quantum well structure, and a different phase 103 different from the parent phase 104 exists in the thermoelectric conversion phase. Here, the quantum well structure refers to a structure in which the moving direction of electrons is constrained by sandwiching the thermoelectric conversion phase 102 having a small band gap between the phases 101 having a large band gap. At this time, the thickness of the thermoelectric conversion phase 102 is desirably 10 nm or less. This is because the effect of improving the Seebeck coefficient due to the quantum confinement effect is exhibited when the thickness is 10 nm or less.
図２は熱電変換相１０２の上面模式図である。熱電変換相１０２には、母相１０４を柱状の異相１０３が複数本貫通している。異相１０３の上端面と下端面は熱電変換相を挟む相１０１と接触しており、異相１０３の上端面から下端面までは途中で途切れず連続している。言い換えると、複数本の立設した異相１０３間を母相１０４で満たすことで熱電変換相１０２を形成している。そのため、熱電変換相１０２の上面図も横断面図も、母相１０４中に異相１０３が分散した様子となる。 FIG. 2 is a schematic top view of the thermoelectric conversion phase 102. In the thermoelectric conversion phase 102, a plurality of columnar heterogeneous phases 103 penetrates the matrix phase 104. The upper end surface and the lower end surface of the different phase 103 are in contact with the phase 101 sandwiching the thermoelectric conversion phase, and the upper end surface and the lower end surface of the different phase 103 are continuous without interruption. In other words, the thermoelectric conversion phase 102 is formed by filling a plurality of standing heterogeneous phases 103 with the mother phase 104. Therefore, both the top view and the cross-sectional view of the thermoelectric conversion phase 102 show that the heterogeneous phase 103 is dispersed in the matrix phase 104.
熱電変換相を挟む相１０１は、電気的に熱電変換相１０２よりも高抵抗であることが求められ、絶縁層であることが好ましい。これは、熱電変換相１０２と同程度以下の電気抵抗である場合には、電子の閉じ込め効果が低減し、ゼーベック係数向上の効果が得られにくくなるためである。 The phase 101 sandwiching the thermoelectric conversion phase is required to be electrically higher in resistance than the thermoelectric conversion phase 102, and is preferably an insulating layer. This is because when the electric resistance is equal to or lower than that of the thermoelectric conversion phase 102, the effect of confining electrons is reduced, and the effect of improving the Seebeck coefficient is difficult to obtain.
また、熱電変換相を挟む相１０１は、非晶質であることが望ましい。これは、非晶質になることでフォノンを散乱しやすくなり、熱伝導率を低下させることができるためである。熱伝導率が低下することにより、変換効率を向上させることができる。ＳｉＯ2などを含む非晶質酸化物であれば、高抵抗と低熱伝導率を満たすことができるために特に望ましい。このとき、熱電変換相を挟む相１０１は、ＳｉＯ2成分の他にＢ2Ｏ3やＡｌ2Ｏ3やＺｎＯなどのガラス形成成分が入っていても良い。 Moreover, it is desirable that the phase 101 sandwiching the thermoelectric conversion phase is amorphous. This is because it becomes easy to scatter phonons by becoming amorphous, and thermal conductivity can be lowered. By reducing the thermal conductivity, the conversion efficiency can be improved. An amorphous oxide containing SiO 2 or the like is particularly desirable because it can satisfy high resistance and low thermal conductivity. At this time, the phase 101 sandwiching the thermoelectric conversion phase may contain glass forming components such as B 2 O 3 , Al 2 O 3, and ZnO in addition to the SiO 2 component.
本実施形態の熱電変換相１０２の微細構造を形成する手法としては特に限定されるところではないが、共スパッタ法が挙げられる。共スパッタ法とは、複数種のターゲットを同時にスパッタする方法である。熱電変換相１０２の母相１０４となる元素を含むターゲットと、母相とは固溶体を形成しない異相１０３を形成する元素を含むターゲットとを同時にスパッタすることによって、母相１０４と異相１０３との相分離現象が生じ、母相１０４と異相１０３とがあまり混ざらずに母相同士、異相同士で自己組織化し、図２に示すような熱電変換相１０２を形成することができる。 A technique for forming the fine structure of the thermoelectric conversion phase 102 of the present embodiment is not particularly limited, and a co-sputtering method may be mentioned. The co-sputtering method is a method in which a plurality of types of targets are sputtered simultaneously. By simultaneously sputtering a target including an element that becomes the parent phase 104 of the thermoelectric conversion phase 102 and a target including an element that forms the different phase 103 that does not form a solid solution with the parent phase, a phase between the parent phase 104 and the different phase 103 is obtained. A separation phenomenon occurs, and the matrix phase 104 and the heterogeneous phase 103 are not mixed so much that the matrix phases and the heterogeneous phases self-organize to form a thermoelectric conversion phase 102 as shown in FIG.
熱電変換相１０２の母相１０４は、特に限定されるところではないが、例えばＢｉ、Ｂｉ2Ｔｅ3、ＰｂＴｅ、ＮａＣｏＯ2、Ｃａ3Ｃｏ4Ｏ9、Ｓｉ、ＳｉＧｅなど一般的に熱電変換材料として特性が良好な材料を使用することができる。この中でも特にＢｉを使用することが望ましい。この理由は、Ｂｉは、フェルミ波長が長いために量子サイズ効果を得やすく、ナノサイズ化したときに得られる効果が大きいためである。このＢｉには、キャリア濃度をコントロールするために微小のＴｅやＳｂなどのドーピングがされることが望ましい。 The parent phase 104 of the thermoelectric conversion phase 102 is not particularly limited. For example, Bi, Bi 2 Te 3 , PbTe, NaCoO 2 , Ca 3 Co 4 O 9 , Si, and SiGe are generally used as thermoelectric conversion materials. Materials with good properties can be used. Among these, it is particularly preferable to use Bi. This is because Bi has a long Fermi wavelength, so that it is easy to obtain the quantum size effect, and the effect obtained when nano-sized is large. This Bi is preferably doped with a minute amount of Te, Sb or the like in order to control the carrier concentration.
熱電変換相１０２中に存在する異相１０３は、母相１０４と固溶しない物質であればよい。酸化物は、熱電変換相１０２の材料とは固溶体を形成しにくく、ほとんどの種類を用いることができる。異相１０３も熱伝導率が低い方が良いため、非晶質化しやすいＳｉＯ2などを用いることが望ましい。また、異相１０３と熱電変換相を挟む相１０１とが酸化物の場合には、両者の密着性も向上させることができる。 The heterogeneous phase 103 present in the thermoelectric conversion phase 102 may be any substance that does not dissolve in the matrix phase 104. Oxide hardly forms a solid solution with the material of the thermoelectric conversion phase 102, and almost any kind can be used. Since the heterogeneous phase 103 preferably has a low thermal conductivity, it is desirable to use SiO 2 or the like that is easily amorphized. Further, when the heterogeneous phase 103 and the phase 101 sandwiching the thermoelectric conversion phase are oxides, the adhesion between them can also be improved.
図３には、本実施形態の熱電変換材料を用いて作製したπ型熱電変換モジュール３００の一例を示す。熱電変換モジュール３００は、高温部と低温部の温度差を利用して電気を取り出す、もしくは電気を流すことにより発熱部と吸熱部を発生させることを可能とするデバイスである。 FIG. 3 shows an example of a π-type thermoelectric conversion module 300 manufactured using the thermoelectric conversion material of the present embodiment. The thermoelectric conversion module 300 is a device that can generate a heat generating part and a heat absorbing part by taking out electricity by using a temperature difference between a high temperature part and a low temperature part, or by flowing electricity.
図３に示すように熱電変換モジュール３００は、絶縁性基板３０２の一方の面に取り出し電極３０１を形成し、２枚の絶縁性基板３０２の取り出し電極３０１を向かい合わせて、取り出し電極３０１をＰ型とＮ型の熱電変換素子３０３で接合することで形成される。この絶縁性基板３０２の片側を熱源等に貼り付け、もう片側を水冷や空冷することによって絶縁性基板間に温度差を形成し、発電することができる。ただし、熱電変換モジュールの構造は、特にこれに限定されるところではなく、様々な形態が考えられる。熱電変換素子３０３は、前記熱電変換材料１００を積層し、これを立てて膜の面内方向に温度差を形成することで形成することができる。 As shown in FIG. 3, in the thermoelectric conversion module 300, the extraction electrode 301 is formed on one surface of the insulating substrate 302, the extraction electrodes 301 of the two insulating substrates 302 face each other, and the extraction electrode 301 is formed into a P-type. And an N-type thermoelectric conversion element 303. By attaching one side of the insulating substrate 302 to a heat source or the like and cooling the other side with water or air, a temperature difference can be formed between the insulating substrates to generate electric power. However, the structure of the thermoelectric conversion module is not particularly limited to this, and various forms are conceivable. The thermoelectric conversion element 303 can be formed by stacking the thermoelectric conversion materials 100 and standing up to form a temperature difference in the in-plane direction of the film.
以下、実施例を用いて更に詳細に説明する。ただし、本発明は、ここで取り上げた実施例の記載に限定されることはなく、適宜組み合わせてもよい。 Hereinafter, it demonstrates in detail using an Example. However, the present invention is not limited to the description of the embodiments taken up here, and may be combined as appropriate.
熱電変換材料は、ＲＦマグネトロンスパッタリング法を用いて以下の条件で作製した。Ｂｉのターゲット上にＳｉＯ2の１５ｍｍ角のチップを数個並べたものをターゲットとし、ＲＦ電源を用いてＡｒ流量：５０ｓｃｃｍ、放電圧力０．７Ｐａ、投入電力０．１ｋＷの条件でスパッタした。基板には、ＳｉＯ2を使用し、基板上に約２００ｎｍ成膜を実施した。また、成膜は室温にて行った。 The thermoelectric conversion material was produced under the following conditions using an RF magnetron sputtering method. Sputtering was performed under the conditions of Ar flow rate: 50 sccm, discharge pressure 0.7 Pa, input power 0.1 kW using RF power supply with several SiO 2 15 mm square chips arranged on a Bi target. As the substrate, SiO 2 was used, and a film was formed on the substrate at about 200 nm. The film formation was performed at room temperature.
得られた薄膜のＸ線回折を実施したところ、いずれの試料もＢｉのピークのみが観察されたことから、Ｂｉは結晶として、ＳｉＯ2は非晶質として存在することが判明した。薄膜の組成をエネルギー分散型X線分光法によって分析した結果を表１に示す。形成した薄膜（Ａ−３）のＴＥＭ観察結果を図４に示す。これより、Ｂｉの母体中に数ｎｍ程度のＳｉＯ2の非晶質粒子が分散した微細構造となっていた。 When X-ray diffraction was performed on the obtained thin film, only the peak of Bi was observed in any of the samples. Thus, it was found that Bi was present as crystals and SiO 2 was present as amorphous. Table 1 shows the results of analyzing the composition of the thin film by energy dispersive X-ray spectroscopy. The TEM observation result of the formed thin film (A-3) is shown in FIG. Thus, a fine structure in which amorphous particles of SiO 2 of about several nm were dispersed in the Bi matrix.
また、表１には熱伝導率の評価結果も示した。作製したサンプルの熱伝導率の評価は、薄膜の上面にＭｏを成膜し、パルス光加熱サーモリフレクタンス法を用いて実施した。表１には、比較例Ａ−１サンプルの熱伝導率よりも高くなったものを「×」、０．９以上１．０倍未満の同等であったものを「○」、０．６以上０．９倍未満のものを「◎」として相対評価したものを示した。 Table 1 also shows the evaluation results of thermal conductivity. Evaluation of the thermal conductivity of the produced sample was performed by depositing Mo on the upper surface of the thin film and using the pulsed light heating thermoreflectance method. In Table 1, “X” indicates that the thermal conductivity of the sample of Comparative Example A-1 is higher, “○” indicates that the sample is equivalent to 0.9 or more and less than 1.0 times, and “0.6” or greater. Those less than 0.9 times were shown as relative evaluation as “◎”.
さらに、四端子法によって測定した電気抵抗値を同様に相対評価したものを表１に示した。電気抵抗値に関しては、比較例Ａ−１サンプルの電気抵抗値の２．０倍以上のものを「×」、１．５倍以上２．０倍未満のものを「△」、１．０倍以上１．５倍未満のものを「○」として評価した。ゼーベック係数に関しては、室温でゼーベック係数測定装置（Resitest8300：東陽テクニカ製）を使用して測定した値を示した。 Further, Table 1 shows the relative evaluation of the electrical resistance values measured by the four probe method. Regarding the electrical resistance value, 2.0 times or more of the electrical resistance value of Comparative Example A-1 sample is “x”, 1.5 times or more and less than 2.0 times “Δ”, 1.0 times Those with less than 1.5 times were evaluated as “◯”. Regarding the Seebeck coefficient, the value measured using a Seebeck coefficient measuring device (Resitest 8300: manufactured by Toyo Technica) at room temperature is shown.
表１の結果より、熱電変換相中に異相が存在することによって、その特性が向上できることが判明した。 From the results in Table 1, it has been found that the presence of a heterogeneous phase in the thermoelectric conversion phase can improve the characteristics.
熱電変換材料の膜厚依存性の検討を、ＲＦマグネトロンスパッタリング法を用いて実施例１と同様の条件で実施した。薄膜の組成は、実施例１のＡ−３サンプルと同じものを用いて、表２のＢ−１〜Ｂ−６に示す膜厚になるように成膜した。また、成膜したサンプルの上からさらに、ＲＦマグネトロンスパッタリング（Ａｒ流量：５０ｓｃｃｍ、放電圧力０．７Ｐａ、投入電力０．３ｋＷ）によって、１０ｎｍのＳｉＯ2を成膜することで図１に示すような超格子構造を作製した。 The film thickness dependence of the thermoelectric conversion material was examined under the same conditions as in Example 1 using the RF magnetron sputtering method. The composition of the thin film was the same as that of the A-3 sample of Example 1, and was formed so as to have film thicknesses shown in B-1 to B-6 of Table 2. Further, by depositing 10 nm of SiO 2 on the deposited sample by RF magnetron sputtering (Ar flow rate: 50 sccm, discharge pressure 0.7 Pa, input power 0.3 kW) as shown in FIG. A superlattice structure was fabricated.
作製したサンプルは、実施例１と同様にゼーベック係数測定装置を用いて評価した。その結果を表２に示す。 The produced samples were evaluated using a Seebeck coefficient measuring apparatus in the same manner as in Example 1. The results are shown in Table 2.
以上の結果より、１０ｎｍ以下の薄膜となったときに量子閉じ込め構造によってゼーベック係数が格段に向上することが確認された。 From the above results, it was confirmed that the Seebeck coefficient was remarkably improved by the quantum confinement structure when the thin film was 10 nm or less.
Ｂｉ2Ｔｅ3ターゲット上にＳｉＯ2の１５ｍｍ角のチップを５個並べたものをターゲットとし、実施例１と同様にＲＦマグネトロンスパッタリングを実施した。スパッタ条件は、Ａｒ流量：５０ｓｃｃｍ、放電圧力０．７Ｐａ、投入電力０．１ｋＷで行った。基板は、実施例１と同様にＳｉＯ2を用いた。成膜は、基板温度４００℃にて行い、厚み１０ｎｍを成膜した。 RF magnetron sputtering was performed in the same manner as in Example 1 using five Bi 2 Te 3 targets on which five 15 mm square chips of SiO 2 were arranged. The sputtering conditions were Ar flow rate: 50 sccm, discharge pressure 0.7 Pa, and input power 0.1 kW. As for the substrate, SiO 2 was used as in Example 1. Film formation was performed at a substrate temperature of 400 ° C., and a film having a thickness of 10 nm was formed.
得られた薄膜のＴＥＭ観察を実施したところ、図４と同等の微細組織を形成していることが確認できた。また、比較としてＢｉ2Ｔｅ3単体を同様の条件で成膜した。これらの薄膜に対し、実施例２と同様に１０ｎｍのＳｉＯ2を成膜することで、図１に示すような超格子構造を作製した。 When the TEM observation of the obtained thin film was implemented, it has confirmed that the fine structure equivalent to FIG. 4 was formed. For comparison, a Bi 2 Te 3 simple substance was formed under the same conditions. A superlattice structure as shown in FIG. 1 was produced by depositing 10 nm of SiO 2 on these thin films in the same manner as in Example 2.
また、熱伝導率の測定を実施例１と同様に行ったところ、Ｂｉ2Ｔｅ3単体を成膜した比較例と比べて０．８４倍となっていたことから、熱伝導率の低減が確認できた。 Further, when the thermal conductivity was measured in the same manner as in Example 1, it was 0.84 times that of the comparative example in which the Bi 2 Te 3 single film was formed, and it was confirmed that the thermal conductivity was reduced. did it.
熱電変換材料は、ＤＣマグネトロンスパッタリング法を用いて以下の条件で作製した。Ｂｉのターゲット上にＳｉの１０ｍｍ角のチップを８個並べたものをターゲットとし、ＤＣ電源を用いてＡｒ流量：５０ｓｃｃｍ、放電圧力０．７Ｐａ、投入電力０．１ｋＷの条件でスパッタした。基板には、ＳｉＯ2を使用し、基板上に約１０ｎｍ成膜を実施した。また、成膜は室温にて行った。 The thermoelectric conversion material was produced using the DC magnetron sputtering method under the following conditions. Sputtering was performed under the conditions of Ar flow rate: 50 sccm, discharge pressure 0.7 Pa, and input power 0.1 kW using a DC power supply with eight Si 10 mm square chips arranged on a Bi target. As the substrate, SiO 2 was used, and a film was formed on the substrate with a thickness of about 10 nm. The film formation was performed at room temperature.
得られた薄膜のＴＥＭ観察を実施したところ、図４と同様の微細組織を形成していることが確認できた。また、比較としてＢｉ単体を同様の条件にて成膜した。続いて、その上からＤＣマグネトロンスパッタリング法（Ａｒ流量：５０ｓｃｃｍ、放電圧力０．７Ｐａ、投入電力０．３ｋＷ）によって、それぞれ１０ｎｍのＳｉを成膜することで図１に示すような超格子構造を作製した。 When the TEM observation of the obtained thin film was implemented, it has confirmed that the same fine structure as FIG. 4 was formed. For comparison, a single Bi film was formed under the same conditions. Subsequently, a 10 nm Si film is formed on each of them by a DC magnetron sputtering method (Ar flow rate: 50 sccm, discharge pressure 0.7 Pa, input power 0.3 kW) to form a superlattice structure as shown in FIG. Produced.
作製したサンプルをＸＲＤ分析した結果からはＢｉのピークのみが観察されたことから、異相として熱電変換相中に存在するＳｉ及び上面に成膜しているＳｉはどちらも非晶質で存在することが判明した。さらに、実施例１と同様に熱伝導率の測定を実施したところ、Ｂｉ単体を成膜した比較例と比べて０．８８倍になっていたことから熱伝導率の低減が確認できた。 From the results of XRD analysis of the prepared sample, only the Bi peak was observed, and therefore Si present in the thermoelectric conversion phase as a different phase and Si deposited on the upper surface were both present in an amorphous state. There was found. Further, when the thermal conductivity was measured in the same manner as in Example 1, it was confirmed that the thermal conductivity was reduced because it was 0.88 times that of the comparative example in which the Bi alone was formed.
実施例２と同様の条件でＢ−１のサンプルとＢ−５のサンプルの薄膜を幅４ｍｍ、厚み０．５ｍｍのＳｉＯ2基板上に作製した。このとき、実施例２では、１０ｎｍの熱電変換相と１０ｎｍのＳｉＯ2相を形成したが、本実施例においてはこのプロセスを５０回繰り返し、厚み約１μｍの薄膜とした。 Under the same conditions as in Example 2, samples B-1 and B-5 were prepared on a SiO 2 substrate having a width of 4 mm and a thickness of 0.5 mm. At this time, in Example 2, a 10 nm thermoelectric conversion phase and a 10 nm SiO 2 phase were formed. In this example, this process was repeated 50 times to obtain a thin film having a thickness of about 1 μm.
次に、この作製した成膜基板にマスクをして側面にのみＤＣマグネトロンスパッタリング法（Ａｒ流量：５０ｓｃｃｍ、放電圧力０．７Ｐａ、投入電力０．３ｋＷ）によってＮｉスパッタをして熱電変換素子とした。この熱電変換素子を薄膜の面内方向に温度差が取れるようにＡｌＮ基板の上に立て、熱電変換素子とＡｌＮ基板とを銀ペーストで接続することで、π型熱電変換モジュールを形成した。接続時に銀ペーストを１５０℃、３０分間加熱した。この熱電変換モジュールの片面にホットプレートをあて、５０℃まで加熱したところ、電力を発生したことから熱電変換モジュールとして正常に動作することが確認できた。 Next, the produced film formation substrate was masked, and Ni was sputtered only on the side surface by a DC magnetron sputtering method (Ar flow rate: 50 sccm, discharge pressure 0.7 Pa, input power 0.3 kW) to form a thermoelectric conversion element. . This thermoelectric conversion element was stood on an AlN substrate so that a temperature difference could be taken in the in-plane direction of the thin film, and the thermoelectric conversion element and the AlN substrate were connected with a silver paste to form a π-type thermoelectric conversion module. At the time of connection, the silver paste was heated at 150 ° C. for 30 minutes. When a hot plate was applied to one side of this thermoelectric conversion module and heated to 50 ° C., it was confirmed that the thermoelectric conversion module operates normally because electric power was generated.
１００：熱電変換材料、１０１：熱電変換相を挟む相、１０２：熱電変換相、１０３：母相と異なる異相（異相）、１０４：母相、３００：熱電変換モジュール、３０１：取り出し電極、３０２：絶縁性基板、３０３：熱電変換素子 100: thermoelectric conversion material, 101: phase sandwiching the thermoelectric conversion phase, 102: thermoelectric conversion phase, 103: different phase (different phase) different from the parent phase, 104: parent phase, 300: thermoelectric conversion module, 301: extraction electrode, 302: Insulating substrate, 303: thermoelectric conversion element
Claims (12)
前記第１の相を形成する工程は、複数種のターゲットをスパッタすることにより、一の前記ターゲットに含まれる元素を含む母相と、他の前記ターゲットに含まれる元素を含む異相とを備える前記第１の相を形成する工程であり、
前記第２の相を形成する工程は、前記母相と異なるターゲットをスパッタすることにより、前記母相と異なるターゲットに含まれる元素を含む薄膜状の前記第２の相を前記第１の相上に形成する工程である
ことを特徴とする熱電変換材料の製造方法。 Forming a thin film-like first phase on the substrate; and forming a thin film-like second phase on the first phase,
The step of forming the first phase includes a mother phase containing an element contained in one of the targets and a heterogeneous phase containing an element contained in the other target by sputtering a plurality of types of targets. Forming a first phase;
The step of forming the second phase is performed by sputtering a target different from the parent phase so that the thin film-like second phase containing an element contained in the target different from the parent phase is formed on the first phase. A process for producing a thermoelectric conversion material, which is a step of forming a thermoelectric conversion material.
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| JP2019537275A (en) * | 2016-09-21 | 2019-12-19 | トヨタ・モーター・ヨーロッパＴｏｙｏｔａ Ｍｏｔｏｒ Ｅｕｒｏｐｅ | Multilayer thin film and its preparation |
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| JP2018056161A (en) * | 2016-09-26 | 2018-04-05 | 株式会社東芝 | Thermoelectric conversion device |
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