JPWO2017037884A1 - Thermoelectric conversion material, thermoelectric conversion element and thermoelectric conversion module using the same - Google Patents

Thermoelectric conversion material, thermoelectric conversion element and thermoelectric conversion module using the same Download PDF

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JPWO2017037884A1
JPWO2017037884A1 JP2017537132A JP2017537132A JPWO2017037884A1 JP WO2017037884 A1 JPWO2017037884 A1 JP WO2017037884A1 JP 2017537132 A JP2017537132 A JP 2017537132A JP 2017537132 A JP2017537132 A JP 2017537132A JP WO2017037884 A1 JPWO2017037884 A1 JP WO2017037884A1
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早川　純
純 早川
健 黒崎
健 黒崎
ユスフ エクバル
ユスフ エクバル
伸介 山中
伸介 山中
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    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
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Abstract

比抵抗低減と熱伝導率低減とが両立可能な熱電変換材料およびそれを用いた熱電変換効率の高い熱電変換素子並びに熱電変換モジュールを提供するために、イオン化不純物３０を含むキャリア供給相２０と、キャリア供給相２０よりもイオン化不純物濃度が低い母相１０とを含み、母相１０とキャリア供給相２０の粒径が１００ｎｍ以下で、キャリア供給相２０で生じるキャリア４０は母相内へ注入されキャリア４１として母相内を伝導する熱電変換材料とする。In order to provide a thermoelectric conversion material in which specific resistance reduction and thermal conductivity reduction are compatible, a thermoelectric conversion element having high thermoelectric conversion efficiency, and a thermoelectric conversion module using the thermoelectric conversion material, a carrier supply phase 20 containing ionized impurities 30; Including a mother phase 10 having a lower ionized impurity concentration than the carrier supply phase 20, the particle size of the mother phase 10 and the carrier supply phase 20 is 100 nm or less, and the carrier 40 generated in the carrier supply phase 20 is injected into the mother phase. 41 is a thermoelectric conversion material that conducts in the matrix.

Description

本発明は、熱電変換材料及びそれを用いた熱電変換素子並びに熱電変換モジュールに関する。   The present invention relates to a thermoelectric conversion material, a thermoelectric conversion element using the material, and a thermoelectric conversion module.

近年、再生可能エネルギー利用に注目が集まる中、産業排熱を電気エネルギーとして利用する発電技術に注目が集まっている。特に熱密度の薄い領域や空間的にタービンの設計が難しい領域に対しては、ゼーベック効果を利用した熱電変換材料・熱電変換素子・熱電変換モジュールが提案されている。   In recent years, attention has been focused on power generation technology that uses industrial waste heat as electrical energy, while attention has been focused on the use of renewable energy. In particular, thermoelectric conversion materials, thermoelectric conversion elements, and thermoelectric conversion modules using the Seebeck effect have been proposed for regions where the heat density is low or where it is difficult to design the turbine spatially.

このゼーベック効果を利用した熱電変換材料の性能は、一般に下式（１）で表わされる無次元単位の性能指数ＺＴにて評価される。   The performance of the thermoelectric conversion material using the Seebeck effect is generally evaluated by a dimensionless figure of merit ZT represented by the following formula (1).

ＺＴ＝Ｓ２Ｔ／（ρκ） （１）
上式（１）において、Ｓはゼーベック係数を、Ｔは絶対温度を、ρは比抵抗、κは熱伝導率を表わす。ZT = S 2 T / (ρκ) (1)
In the above equation (1), S represents the Seebeck coefficient, T represents the absolute temperature, ρ represents the specific resistance, and κ represents the thermal conductivity.

上式（１）から、熱電性能を向上させるためには、ゼーベック係数Ｓを大きくし、比抵抗ρおよび熱伝導率κを小さくすれば良いことがわかる。   From the above equation (1), it can be seen that in order to improve the thermoelectric performance, the Seebeck coefficient S may be increased, and the specific resistance ρ and the thermal conductivity κ may be decreased.

このような熱電材料としては、
（１）Ｂｉ−Ｔｅ系、Ｐｂ−Ｔｅ系の化合物
（２）ＮａｘＣｏＯ２（０．３≦ｘ≦０．８）、（ＺｎＯ）ｍＩｎ２Ｏ３（１≦ｍ≦１９）系の酸化物材料
（３）Ｚｎ−Ｓｂ系、Ｃｏ−Ｓｂ
系、Ｆｅ−Ｓｂ系等のスクッテルダイト化合物
（４）ＺｒＮｉＳｎ等のハーフホイスラー化合物
（５）Ｓｉ−ＧｅやＭｇ−Ｓｉなどのシリサイド及びシリコン半導体化合物
などが知られている。As such a thermoelectric material,
(1) Bi-Te and Pb-Te compounds (2) Na x CoO 2 (0.3 ≦ x ≦ 0.8), (ZnO) mIn 2 O 3 (1 ≦ m ≦ 19) oxidation Material (3) Zn-Sb, Co-Sb
Known are skutterudite compounds such as Fe-Sb type, (4) half-Heusler compounds such as ZrNiSn, (5) silicides such as Si-Ge and Mg-Si, and silicon semiconductor compounds.

特に（５）のシリサイドやシリコン化合物は、資源量が豊富かつ無毒なＳｉを用いるため非常に注目されている。Ｓｉは、比較的ゼーベック係数Ｓが大きく、ドーピングによるキャリア数の変調による比抵抗の制御が容易という利点がある（例えば特許文献１）。また、熱伝導率を低減するために結晶粒径をナノスケールにした構造が適用される事例がある。（例えば、特許文献２、３）具体的には、Ｓｉに他元素をドープしたＭｇ２Ｓｉ、ＭｎＳｉａ、ＦｅＳｉ２、Ｃａ２Ｓｉ、Ｃａ３Ｓｉ４、ＢａＳｉ２、ＭｏＳｉ２、ＷＳｉ２、ＣｒＳｉ２などのシリサイドと、Ｌｉ４Ｓｉ２３、Ｎａ４Ｓｉ２３などを母材料としたシリコン系クラスレートなどが挙げられる。しかし、ドーピングによりキャリア数を増加すると、イオン化不純物濃度が増加し伝導電子（あるいはホール）の散乱確率が増大し、比抵抗が増大しＺＴが減少する傾向を示し十分な性能が得られない。また、結晶粒径をナノスケールにした場合、結晶粒界数が増加しキャリアの粒界散乱が生じ、十分な比抵抗低減を実現できない。このようにシリサイドに代表される熱電変換材料においてＺＴを向上されるためには、比抵抗低減と熱伝導率低減の両立が必要となっている。In particular, the silicide and silicon compound of (5) are attracting a great deal of attention because they use abundant and non-toxic Si. Si has an advantage that the Seebeck coefficient S is relatively large and the resistivity can be easily controlled by modulating the number of carriers by doping (for example, Patent Document 1). In addition, there is a case where a structure having a crystal grain size of nanoscale is applied in order to reduce the thermal conductivity. (For example, Patent Documents 2 and 3) Specifically, Mg 2 Si, MnSi a , FeSi 2 , Ca 2 Si, Ca 3 Si 4 , BaSi 2 , MoSi 2 , WSi 2 , CrSi doped with other elements in Si 2 and the like, and silicon-based clathrate using, as a base material, Li 4 Si 23 , Na 4 Si 23, or the like. However, when the number of carriers is increased by doping, the ionized impurity concentration increases, the conduction electron (or hole) scattering probability increases, the specific resistance increases, and ZT tends to decrease, and sufficient performance cannot be obtained. In addition, when the crystal grain size is made nanoscale, the number of crystal grain boundaries increases and carrier grain boundary scattering occurs, and a sufficient reduction in specific resistance cannot be realized. Thus, in order to improve ZT in a thermoelectric conversion material typified by silicide, it is necessary to achieve both reduction in specific resistance and reduction in thermal conductivity.

一方、へテロ接合薄膜を用いた２次元電子ガス生成による比抵抗低減と熱伝導率低減の両立する技術の事例がある（例えば、特許文献４、非特許文献１）が、電力規模が小さく３次元バルク形態での実現が課題である。   On the other hand, there are examples of techniques that achieve both reduction of specific resistance and reduction of thermal conductivity by generating a two-dimensional electron gas using a heterojunction thin film (for example, Patent Document 4 and Non-Patent Document 1). Realization in a dimensional bulk form is an issue.

特開２０１３−１７９３２２号公報JP 2013-179322 A 特開２００９−１９４０８５号公報JP 2009-194085 A 特開２０１３−８７４７号公報JP 2013-8747 A 特許第４９９８８９７号公報Japanese Patent No. 4999897

L. D. Hicks and M. S. Dresselhaus, Phys. Rev. B47, 12727 (1993).L. D. Hicks and M. S. Dresselhaus, Phys. Rev. B47, 12727 (1993).

前述のとおり、シリサイド、シリコン半導体化合物では、比抵抗低減を目的に他元素ドーピングによるキャリア数増大を行うとイオン化不純物濃度の増大によるキャリアの散乱が増し十分な比抵抗低減が得られない。また、熱伝導率低減するために結晶粒径のナノスケール化を行った場合、キャリアの結晶粒界散乱が増加し十分な比抵抗低減に限界がある。   As described above, in silicide and silicon semiconductor compounds, if the number of carriers is increased by doping other elements for the purpose of reducing specific resistance, carrier scattering increases due to increase in ionized impurity concentration, and sufficient specific resistance cannot be reduced. In addition, when the crystal grain size is made nanoscale in order to reduce the thermal conductivity, the crystal grain boundary scattering of the carrier increases, and there is a limit to a sufficient specific resistance reduction.

本発明の目的は、比抵抗低減と熱伝導率低減とが両立可能な熱電変換材料及びそれを用いた熱電変換効率の高い熱電変換素子並びに熱電変換モジュールを提供することにある。   An object of the present invention is to provide a thermoelectric conversion material capable of achieving both a reduction in specific resistance and a reduction in thermal conductivity, a thermoelectric conversion element using the thermoelectric conversion element, and a thermoelectric conversion module using the thermoelectric conversion efficiency.

上記目的を達成するための一実施形態として、イオン化不純物を含むキャリア供給相からなる第１粒子と、
前記キャリア供給相よりもイオン化不純物濃度が低い母相からなる第２粒子と、を含む熱電変換材料であって、
前記第１粒子と前記第２粒子の粒径は、共に１００ｎｍ以下であり、
前記キャリア供給相に含まれた不純物により生じるキャリアは、前記母相内へ注入され前記母相内を伝導するものであることを特徴とする熱電変換材料とする。As one embodiment for achieving the above object, first particles comprising a carrier supply phase containing ionized impurities,
A thermoelectric conversion material comprising: second particles composed of a parent phase having a lower ionized impurity concentration than the carrier supply phase,
The particle diameters of the first particles and the second particles are both 100 nm or less,
Carriers generated by impurities contained in the carrier supply phase are injected into the mother phase and conducted in the mother phase, thereby providing a thermoelectric conversion material.

また、他の実施形態として、電力を取り出すための電極で接続されたｎ型熱電変換材料とｐ型熱電変換材料との一対で構成され、ゼーベック効果を用いて発電する熱電変換素子において、
前記ｎ型およびｐ型熱電変換材料の少なくとも一者は、
イオン化不純物を含むキャリア供給相からなる第１粒子と、
前記キャリア供給相よりもイオン化不純物濃度が低い母相からなる第２粒子と、を含み、
前記第１粒子と前記第２粒子の粒径は、共に１００ｎｍ以下であり、
前記キャリア供給相に含まれた不純物により生じるキャリアは、前記母相内へ注入され前記母相内を伝導するものであることを特徴とする熱電変換素子とする。Further, as another embodiment, in a thermoelectric conversion element configured by a pair of an n-type thermoelectric conversion material and a p-type thermoelectric conversion material connected by an electrode for extracting electric power, and generating electric power using the Seebeck effect,
At least one of the n-type and p-type thermoelectric conversion materials is:
First particles comprising a carrier supply phase containing ionized impurities;
Second particles composed of a parent phase having a lower ionized impurity concentration than the carrier supply phase,
The particle diameters of the first particles and the second particles are both 100 nm or less,
Carriers generated by impurities contained in the carrier supply phase are injected into the mother phase and conducted in the mother phase, thereby providing a thermoelectric conversion element.

また、他の実施形態として、電力を取り出すための電極で接続されたｎ型熱電変換材料とｐ型熱電変換材料の複数対で構成され、ゼーベック効果を用いて発電する熱電変換モジュールにおいて、
前記ｎ型およびｐ型熱電変換材料の少なくとも一者は、
イオン化不純物を含むキャリア供給相からなる第１粒子と、
前記キャリア供給相よりもイオン化不純物濃度が低い母相からなる第２粒子と、を含み、
前記第１粒子と前記第２粒子の粒径は、共に１００ｎｍ以下であり、
前記キャリア供給相に含まれた不純物により生じるキャリアは、前記母相内へ注入され前記母相内を伝導するものであることを特徴とする熱電変換モジュールとする。Further, as another embodiment, in a thermoelectric conversion module configured by a plurality of pairs of an n-type thermoelectric conversion material and a p-type thermoelectric conversion material connected by an electrode for extracting electric power, and generating electric power using the Seebeck effect,
At least one of the n-type and p-type thermoelectric conversion materials is:
First particles comprising a carrier supply phase containing ionized impurities;
Second particles composed of a parent phase having a lower ionized impurity concentration than the carrier supply phase,
The particle diameters of the first particles and the second particles are both 100 nm or less,
Carriers generated by impurities contained in the carrier supply phase are injected into the mother phase and conducted in the mother phase, thereby providing a thermoelectric conversion module.

本発明によれば、比抵抗低減と熱伝導率低減とが両立可能な熱電変換材料及びそれを用いた熱電変換効率の高い熱電変換素子並びに熱電変換モジュールを提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the thermoelectric conversion material in which specific resistance reduction and thermal conductivity reduction are compatible, a thermoelectric conversion element using the same, and a thermoelectric conversion module and a thermoelectric conversion module can be provided.

本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）の断面模式図であり、（ａ）は複数の母相の粒子とキャリア供給相の粒子を含む組織構成例を、（ｂ）は母相の粒子とキャリア供給相の粒子との界面１５におけるキャリアの移動の例を示す。BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of the thermoelectric conversion material (including a modulation dope structure) according to the first embodiment of the present invention, (a) is a structural configuration example including a plurality of mother phase particles and carrier supply phase particles, (B) shows an example of carrier movement at the interface 15 between the mother phase particles and the carrier supply phase particles. （ａ）は本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）において母相１０とキャリア供給相２０がともにｎ型材料で構成される両相の界面のエネルギーバンド図を、（ｂ）は本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）において母相１０とキャリア供給相２０がともにｐ型材料で構成される両相の界面のエネルギーバンド図を、（ｃ）は変調ドープ構造をもたない単物質においてドーピングしたときの伝導状態の模式図を示す。(A) is an energy band diagram of an interface between both phases in which the parent phase 10 and the carrier supply phase 20 are both made of an n-type material in the thermoelectric conversion material (including the modulation dope structure) according to the first embodiment of the present invention. (B) is the energy of the interface between both phases in which the parent phase 10 and the carrier supply phase 20 are both made of p-type material in the thermoelectric conversion material (including the modulation dope structure) according to the first embodiment of the present invention. A band diagram is shown, and (c) is a schematic diagram of a conduction state when doping is performed on a single material having no modulation doping structure. 本発明の第１の実施例に係る熱電変換材料の母相１０とキャリア供給相２０に使用する材料の最適な組み合わせを示す。The optimal combination of the material used for the parent | base phase 10 and the carrier supply phase 20 of the thermoelectric conversion material which concerns on 1st Example of this invention is shown. 本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）の作製プロセスフローの一例を示す。1 shows an example of a manufacturing process flow of a thermoelectric conversion material (including a modulation dope structure) according to a first embodiment of the present invention. 本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）のＸ線回折結果の一例を示す。An example of the X-ray-diffraction result of the thermoelectric conversion material (a modulation | alteration dope structure is included) which concerns on the 1st Example of this invention is shown. 上図は図１(a)に示す組織構成における粒径の一例を示す断面模式図、下図は本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）の母相１０にＳｉを選択した場合において、結晶粒径を変化させたときの熱伝導率の温度依存性を示す。The upper figure is a schematic cross-sectional view showing an example of the particle diameter in the structure shown in FIG. 1 (a), and the lower figure shows the matrix 10 of the thermoelectric conversion material (including the modulation dope structure) according to the first embodiment of the present invention. In the case where Si is selected, the temperature dependence of the thermal conductivity when the crystal grain size is changed is shown. 本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）の母相１０にＳｉを選択場合において、結晶粒径を変化させたときのＺＴの温度依存性の一例を示す。An example of temperature dependence of ZT when the crystal grain size is changed in the case where Si is selected as the parent phase 10 of the thermoelectric conversion material (including the modulation dope structure) according to the first embodiment of the present invention will be shown. 本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）の母相１０にＧｅを選択場合において、結晶粒径を変化させたときのＺＴの温度依存性の一例を示す。An example of temperature dependence of ZT when the crystal grain size is changed in the case where Ge is selected for the parent phase 10 of the thermoelectric conversion material (including the modulation dope structure) according to the first embodiment of the present invention will be shown. 本発明の第２の実施例に係る熱電変換素子の構成例を示す模式斜視図である。It is a model perspective view which shows the structural example of the thermoelectric conversion element which concerns on the 2nd Example of this invention. 本発明の第３の実施例に係る熱電変換モジュールの構成例を示す模式斜視図である。It is a model perspective view which shows the structural example of the thermoelectric conversion module which concerns on the 3rd Example of this invention.

本実施の形態では、ドーピングによりキャリアを供給する相（キャリア供給相と呼ぶ）と供給されたキャリアが伝導する相（母相と呼ぶ）を分離した変調ドープ構造を含む熱電変換材料（以下、変調ドープ型熱電変換材料と呼ぶ場合有り）を提供する。前記キャリア供給相には、ＧａＮ、ＳｉＣ、ＳｒＴｉＯ３、Ｇｅなどを使用し前記母相にはＳｉまたはＧｅの少なくとも一つの元素を含む材料を用いることができる。また、キャリア供給相と母相の結晶粒径は１００ｎｍ以下であることが望ましい。さらに、本実施の形態の変調ドープ型熱電変換材料を用いた熱電変換素子及び熱電変換モジュールを提供する。In the present embodiment, a thermoelectric conversion material (hereinafter referred to as modulation) including a modulation dope structure in which a phase for supplying carriers by doping (referred to as a carrier supply phase) and a phase through which the supplied carriers conduct (referred to as a parent phase) is separated. May be referred to as a doped thermoelectric conversion material). GaN, SiC, SrTiO 3 , Ge, or the like can be used for the carrier supply phase, and a material containing at least one element of Si or Ge can be used for the parent phase. The crystal grain size of the carrier supply phase and the parent phase is desirably 100 nm or less. Furthermore, the thermoelectric conversion element and thermoelectric conversion module using the modulation dope type thermoelectric conversion material of this Embodiment are provided.

以下、本発明について実施例により説明する。なお、同一符号は同一構成要素を示す。   Hereinafter, the present invention will be described with reference to examples. In addition, the same code | symbol shows the same component.

本発明の第１の実施例に係る熱電変換材料について、図１〜図６を用いて説明する。
図１は本実施例に係る変調ドープ型熱電変換材料の断面模式図であり、図１（ａ）は複数の母相の粒子とキャリア供給相の粒子を含む組織構成例を示す。この熱電変換材料は、母相１０とキャリア供給相２０の粒子の凝集体で構成される。特に、各相の粒子径は熱伝導率の低減と変調ドープ効果を両立するために１００ｎｍ以下であることが望ましい。The thermoelectric conversion material according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view of a modulation-doped thermoelectric conversion material according to the present embodiment, and FIG. 1 (a) shows a structural configuration example including a plurality of mother phase particles and carrier supply phase particles. This thermoelectric conversion material is composed of an aggregate of particles of the parent phase 10 and the carrier supply phase 20. In particular, the particle diameter of each phase is preferably 100 nm or less in order to achieve both a reduction in thermal conductivity and a modulation doping effect.

図１（ｂ）は、図１（ａ）に示した変調ドープ型熱電変換材料の母相の粒子とキャリア供給相の粒子との界面１５におけるキャリアの移動の例を示す。本図では、キャリア供給相２０においてドーピングした不純物によりイオン化不純物３０とキャリア４０が生成され、そのキャリア４０が母相１０にキャリア４１として伝導する状態を示している。その原理を図２（ａ）、（ｂ）に示すエネルギーバンド図を使って説明する。   FIG. 1B shows an example of carrier movement at the interface 15 between the mother phase particles and the carrier supply phase particles of the modulation-doped thermoelectric conversion material shown in FIG. In the drawing, ionized impurities 30 and carriers 40 are generated by impurities doped in the carrier supply phase 20, and the carriers 40 are conducted to the mother phase 10 as carriers 41. The principle will be described with reference to energy band diagrams shown in FIGS.

図２（ａ）は、母相１０とキャリア供給相２０がともにｎ型材料で構成される両相の界面のエネルギーバンド図を示す。ｎ型であるためキャリアは電子であり伝導帯（ＣＢ）に存在する。キャリア供給相２０は、その伝導帯エネルギーが母相１０の伝導帯エネルギーよりもΔＥｃだけ高いエネルギーになるように物質を選択する。この場合、キャリア供給相２０の電子４０は、ΔＥｃだけエネルギーの低い母相１０の伝導帯エネルギーへ移動し、電子４１は母相１０内を伝導する。   FIG. 2A shows an energy band diagram of an interface between both phases in which the parent phase 10 and the carrier supply phase 20 are both made of an n-type material. Since it is n-type, carriers are electrons and exist in the conduction band (CB). The carrier supply phase 20 selects a material such that its conduction band energy is higher than that of the parent phase 10 by ΔEc. In this case, the electrons 40 of the carrier supply phase 20 move to the conduction band energy of the mother phase 10 whose energy is lower by ΔEc, and the electrons 41 are conducted in the mother phase 10.

図２（ｂ）は、母相１０とキャリア供給相２０がともにｐ型材料で構成される場合を示す。この場合キャリア供給相２０のキャリアはホールであり価電子帯（ＶＢ）に存在する。本構成においては、キャリア供給相２０として、その価電子帯エネルギーが母相１０の荷電子帯エネルギーよりもΔＥｖだけ低いエネルギーとなるように物質を選択する。この場合、キャリア供給相２０のホール４０は、ΔＥｖだけエネルギーの高い母相１０の荷電子帯へ移動し、ホール４１は母相１０内を伝導する。   FIG. 2B shows a case where both the parent phase 10 and the carrier supply phase 20 are made of a p-type material. In this case, the carrier of the carrier supply phase 20 is a hole and exists in the valence band (VB). In this configuration, a substance is selected as the carrier supply phase 20 so that its valence band energy is lower by ΔEv than the valence band energy of the parent phase 10. In this case, the hole 40 of the carrier supply phase 20 moves to the valence band of the parent phase 10 whose energy is higher by ΔEv, and the hole 41 is conducted in the mother phase 10.

このように、変調ドープ型熱電変換材料において母相１０とキャリア供給相２０を最適なエネルギー準位関係をもつ物質を選択組み合わせることにより、ｎ型、ｐ型両極性の変調ドープ型熱電変換材料を実現し、そのキャリアはイオン化不純物が多く存在するキャリア供給相２０からイオン化不純物の存在しない母相１０へ移動し母相１０内を大きな移動度で伝導できる。例えば、その移動度は変調ドープ構造をもたない従来単物質に比べて最大１０倍の移動度を実現し、比抵抗として一桁低減可能である。なお、母相にはイオン化不純物が存在しない方が望ましいが、キャリア供給相よりもイオン化不純物濃度を低くすることにより従来よりも良好な特性を得ることができる。また、母相を構成する材料はキャリア供給相を構成する材料よりもゼーベック係数が大きいことが望ましい。   As described above, by selectively combining the base phase 10 and the carrier supply phase 20 with substances having an optimum energy level relationship in the modulation-doped thermoelectric conversion material, the n-type and p-type bipolar modulation-doped thermoelectric conversion materials can be obtained. As a result, the carriers move from the carrier supply phase 20 in which many ionized impurities are present to the mother phase 10 in which no ionized impurities are present and can be conducted in the mother phase 10 with high mobility. For example, the mobility is up to 10 times that of a conventional single material having no modulation dope structure, and can be reduced by one digit as a specific resistance. Although it is desirable that the mother phase does not contain ionized impurities, it is possible to obtain better characteristics than before by making the ionized impurity concentration lower than that of the carrier supply phase. Further, it is desirable that the material constituting the parent phase has a larger Seebeck coefficient than the material constituting the carrier supply phase.

一方、図２（ｃ）は、本実施例の熱電変換材料と異なり、変調ドープ構造をもたない単物質（熱電変換材料）２１においてドーピングしたときの伝導状態の模式図を示す。ドープした不純物からイオン化不純物３０１とキャリア４０１が生成し、キャリア４１１が単物質２１の中を伝導する。この場合、キャリア４１１は、イオン化不純物が多く存在する単物質２１の中を伝導するためイオン化不純物との衝突により散乱され、移動度が小さくなり比抵抗は増加し、熱電変換の材料性能指数ＺＴの向上には限界がある。   On the other hand, FIG. 2C shows a schematic diagram of a conduction state when doping is performed in a single substance (thermoelectric conversion material) 21 having no modulation doping structure, unlike the thermoelectric conversion material of this example. Ionized impurities 301 and carriers 401 are generated from the doped impurities, and the carriers 411 are conducted through the single substance 21. In this case, the carrier 411 is scattered by collision with the ionized impurity because it conducts through the single substance 21 in which a large amount of ionized impurities are present, the mobility is decreased, the specific resistance is increased, and the material performance index ZT of the thermoelectric conversion is There are limits to improvement.

図３は、本実施例において母相１０とキャリア供給相２０に使用する材料の最適な組み合わせの代表例を示す。母相１０には、Ｓｉ、Ｇｅ、あるいはＴｉを用いることができ、キャリアをｎ型にするためにリン（Ｐ）などをドープ、さらにｐ型にするために硼素（Ｂ）などをドープすることができる。   FIG. 3 shows a representative example of an optimal combination of materials used for the parent phase 10 and the carrier supply phase 20 in this embodiment. The matrix 10 can be made of Si, Ge, or Ti, doped with phosphorus (P) or the like to make the carrier n-type, and further doped with boron (B) or the like to make the p-type. Can do.

母相１０にＳｉを選択した場合、キャリア供給相２０として、Ｓｉの伝導帯（ｎ型の場合）や価電子帯（ｐ型の場合）にエネルギー準位が近いＳｉ（母相１０よりもドープ量を変化させる）、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＳｉδ、ＺｒＴｉδ、ＨｆＳｉδ、ＶＳｉδ、ＭｏＳｉδ、ＷＳｉδなどを選択することができる。これらのキャリア供給相２０に選択された物質もキャリアをｎ型にするためにＰなどをドープ、さらにｐ型にするためにＢなどをドープすることができる。例えば、母相１０にＳｉ、キャリア供給相２０にＳｉＣを選択しｎ型の変調ドープ熱電変換材料を形成する場合、Ｓｉ−ＰとＳｉＣ−Ｐを使用する。When Si is selected as the parent phase 10, the carrier supply phase 20 is Si that has an energy level close to the Si conduction band (in the case of n-type) or valence band (in the case of p-type) (dope more than the parent phase 10). Ge, SiC, GaN, SrTiO 3 , TiSi δ , ZrTi δ , HfSi δ , VSi δ , MoSi δ , WSi δ, etc. can be selected. The material selected for these carrier supply phases 20 can also be doped with P or the like to make the carrier n-type, and further doped with B or the like to make the carrier p-type. For example, when Si is selected for the parent phase 10 and SiC is selected for the carrier supply phase 20 to form an n-type modulation doped thermoelectric conversion material, Si-P and SiC-P are used.

一方、母相１０にＧｅを選択した場合、キャリア供給相２０としてＧｅの伝導帯（ｎ型）や価電子帯（ｐ型）にエネルギー準位が近いＳｉ、Ｇｅ（母相１０よりもドープ量を変化させる）、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＧｅδ、ＺｒＧｅδ、ＨｆＧｅδ、ＶＧｅδ、ＭｏＧｅδ、ＷＧｅδなどを選択することができる。ここで、前述のＳｉを母相１０とした場合と同様にｎ型の場合Ｐなどを、ｐ型の場合Ｂなどを母相１０とキャリア供給相２０にドーピングする。On the other hand, when Ge is selected as the parent phase 10, Si, Ge (the doping amount is higher than that of the parent phase 10) as the carrier supply phase 20 is close to the energy level of Ge conduction band (n-type) or valence band (p-type). SiC, GaN, SrTiO 3 , TiGe δ , ZrGe δ , HfGe δ , VGe δ , MoGe δ , WGe δ and the like can be selected. Here, as in the case where Si is used as the parent phase 10, the parent phase 10 and the carrier supply phase 20 are doped with P or the like in the case of n-type, and B or the like in the case of p-type.

図４Ａは、本実施例に係る変調ドープ型熱電変換材料の作製プロセスフローの一例を示す。ここでは、母相１０にＳｉ、キャリア供給相２０にＳｉ９５Ｇｅ５Ｐ３（以下ＳｉＧｅＰと記載）をそれぞれ８０：２０の原子量比の変調ドープ型熱電変換材料の代表例について説明する。FIG. 4A shows an example of a manufacturing process flow of the modulation dope thermoelectric conversion material according to the present embodiment. Here, a typical example of a modulation-doped thermoelectric conversion material having an atomic weight ratio of 80:20 with Si as the parent phase 10 and Si 95 Ge 5 P 3 (hereinafter referred to as SiGeP) as the carrier supply phase 20 will be described.

ＳｉＧｅＰは、アーク溶解により合成した後、ボールミル ２０分実施して粉砕処理し、フッ酸（ＨＦ）処理を行った。ボールミルで粉砕処理後ＨＦ処理を行ったＳｉ粉砕粉末と前記ＳｉＧｅＰの粉砕粉末とを、目的とする原子量比になるように秤量する。母相１０とキャリア供給相２０の混合比は、それらの物質が共晶や共析など相互に固溶しない比率を選択することが望ましい。この際、原料粉末の酸化等を防ぐために原料粉末が暴露される雰囲気は原料の元素により制御することが望ましい。   SiGeP was synthesized by arc melting, then pulverized by ball milling for 20 minutes and hydrofluoric acid (HF) treatment. The pulverized Si powder after pulverization with a ball mill and the pulverized powder of SiGeP are weighed so as to have a desired atomic weight ratio. As a mixing ratio of the mother phase 10 and the carrier supply phase 20, it is desirable to select a ratio in which these substances do not form a solid solution such as eutectic or eutectoid. At this time, it is desirable to control the atmosphere to which the raw material powder is exposed in order to prevent the raw material powder from being oxidized.

その後、秤量した各原料粉末をボールミルにより３０分粉砕混合する。混合粉砕した粉末の粒径をＸ線回折により評価した結果、平均粒径１３ｎｍの粉末が作製された。ボールミルについては、ボールに所定の粒径になるようにＳＵＳやＺｒＯ２などのボールをそのボール径を選択する。また、遊星ボールミル装置を用いてミル後の粒径が所定の寸法になるように回転数を最適化する。このときに、自転、公転の回転する独立制御してもかまわない。その後、フッ酸（ＨＦ）等の酸により、ボールミル後の微細粒子の表面酸化膜やボールミルのボールとして使用したＺｒＯ２などの酸化膜を除去することが望ましいが、酸化が進行しない材料については実施しない。Then, each raw material powder weighed is pulverized and mixed for 30 minutes by a ball mill. As a result of evaluating the particle size of the mixed and pulverized powder by X-ray diffraction, a powder having an average particle size of 13 nm was produced. For the ball mill, the ball diameter of a ball such as SUS or ZrO 2 is selected so that the ball has a predetermined particle size. Further, the rotational speed is optimized using a planetary ball mill device so that the particle diameter after milling becomes a predetermined size. At this time, independent control of rotation and revolution may be performed. After that, it is desirable to remove the surface oxide film of fine particles after ball milling and an oxide film such as ZrO 2 used as a ball mill ball with an acid such as hydrofluoric acid (HF). do not do.

次に、１３ｎｍに微細化されたＳｉ（母相１０）とＳｉＧｅＰ（キャリア供給相２０）の混合粉末を平均の結晶粒径が１００ｎｍ以下になるように放電プラズマ焼結（ＳＰＳ）により焼結体を作製する。温度は、Ｓｉ（母相１０）とＳｉＧｅＰ（キャリア供給相２０）の融点以下の１０８０℃で設定し、相互に反応しない温度を選定する。また圧力は、焼結体としての密度が９０％以上になるように１００ＭＰａで実施する。   Next, a sintered powder obtained by subjecting a mixed powder of Si (matrix phase 10) and SiGeP (carrier supply phase 20) refined to 13 nm to an average crystal grain size of 100 nm or less by spark plasma sintering (SPS). Is made. The temperature is set at 1080 ° C. below the melting points of Si (matrix phase 10) and SiGeP (carrier supply phase 20), and a temperature at which they do not react with each other is selected. The pressure is 100 MPa so that the density of the sintered body is 90% or more.

図４Ｂは作製した上記焼結体のＸ線回折の結果を示す。この結果（信号強度）から、平均結晶粒径は４０〜７０ｎｍであった。放電プラズマ焼結（ＳＰＳ）の条件は、使用する２つの物質の種類により平均結晶粒径と２つの相が反応しないように、焼結温度、圧力、時間を調整する。このように作製されたＳｉ−ＳｉＧｅＰ変調ドープ構造材料の移動度は、７ｃｍ２／Ｖｓであった。この移動度は、変調ドープ構造をもたないＳｉＧｅＰ単一材料の移動度１．５ｃｍ２／Ｖｓにくらべて約５倍増大した。FIG. 4B shows the result of X-ray diffraction of the produced sintered body. From this result (signal intensity), the average crystal grain size was 40 to 70 nm. The conditions of spark plasma sintering (SPS) adjust the sintering temperature, pressure, and time so that the average crystal grain size and the two phases do not react depending on the types of the two substances used. The mobility of the Si—SiGeP modulation doped structure material thus produced was 7 cm 2 / Vs. This mobility was increased by a factor of about 5 compared to the mobility of 1.5 cm 2 / Vs for the SiGeP single material without the modulation doped structure.

図５の上図は図１(a)に示す組織構成における粒径の一例を示す断面模式図、下図は本発明の第１の実施例に係る熱電変換材料（変調ドープ構造を含む）の母相１０にＳｉを選択した場合において、結晶粒径を変化させたときの熱伝導率の温度依存性を示す。キャリア供給相２０は、Ｓｉ（母相１０よりもドープ量を変化させる）、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＳｉδ、ＺｒＴｉδ、ＨｆＳｉδ、ＶＳｉδ、ＭｏＳｉδ、ＷＳｉδなどの内から選択可能である。また母相１０としてＧｅを選択したい場合も同様の結果を得ることが可能であり、その場合のキャリア供給相２０は、Ｓｉ、Ｇｅ（母相１０よりもドープ量を変化させる）、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＧｅδ、ＺｒＧｅδ、ＨｆＧｅδ、ＶＧｅδ、ＭｏＧｅδ、ＷＧｅδの内から選択される。The upper diagram of FIG. 5 is a schematic sectional view showing an example of the particle diameter in the structure shown in FIG. 1A, and the lower diagram is a mother of a thermoelectric conversion material (including a modulation dope structure) according to the first embodiment of the present invention. In the case where Si is selected as the phase 10, the temperature dependence of the thermal conductivity when the crystal grain size is changed is shown. The carrier supply phase 20 includes Si (which changes the doping amount as compared with the parent phase 10), Ge, SiC, GaN, SrTiO 3 , TiSi δ , ZrTi δ , HfSi δ , VSi δ , MoSi δ , WSi δ and the like. Selectable. Similar results can be obtained when Ge is selected as the parent phase 10, and the carrier supply phase 20 in that case is Si, Ge (the doping amount is changed as compared with the parent phase 10), SiC, GaN. , SrTiO 3 , TiGe δ , ZrGe δ , HfGe δ , VGe δ , MoGe δ , and WGe δ .

この結果から、どの結晶粒径においても熱伝導率は温度とともに減少することがわかる。さらに、結晶粒径を小さくするにつれて熱伝導率は減少し、結晶粒径が５ｎｍでは５Ｗ／Ｋｍと従来のシリコン化合物に比べて１／１０以上低減可能である。一方で、ゼーベック係数と比抵抗の温度変化については本実施例の変調ドープ型熱電変換材料においては結晶粒径１００ｎｍの範囲に対して依存性は小さい。例えば結晶粒径が５ｎｍのサンプルにおけるゼーベック係数は３００Ｋで−２６６μＶ／Ｋであり温度上昇とともに増加し１１００Ｋで−４３０μＶ／Ｋに達する。また、比抵抗は３００Ｋで５μΩｍであり、温度上昇とともに増加し１１００Ｋにおいて１４μΩｍとなる。特に比抵抗は、従来のシリコン化合物に比べて１／２低減可能である。なお、本実施例における最小結晶粒径を５ｎｍとしたが、結晶構造が得られる範囲でこれ以下の粒径とすることもできる。   From this result, it can be seen that the thermal conductivity decreases with temperature at any crystal grain size. Furthermore, as the crystal grain size is reduced, the thermal conductivity decreases, and when the crystal grain size is 5 nm, it is 5 W / Km, which can be reduced by 1/10 or more compared to conventional silicon compounds. On the other hand, the temperature change of the Seebeck coefficient and the specific resistance has little dependence on the range of the crystal grain size of 100 nm in the modulation doped thermoelectric conversion material of this example. For example, the Seebeck coefficient in a sample having a crystal grain size of 5 nm is −266 μV / K at 300 K, increases with increasing temperature, and reaches −430 μV / K at 1100 K. Further, the specific resistance is 5 μΩm at 300K, and increases as the temperature rises to 14 μΩm at 1100K. In particular, the specific resistance can be reduced by half compared to the conventional silicon compound. Although the minimum crystal grain size in this example is 5 nm, the grain size can be smaller than this within the range where the crystal structure can be obtained.

図６Ａは、変調ドープ型熱電変換材料の母相１０にＳｉを選択した場合において、結晶粒径を変化させたときのＺＴの温度依存性の一例を示す。変調ドープ構造の有無に関わらず、どの結晶粒径においてもＺＴは温度とともに増加する。粒径１００ｎｍの変調ドープ型熱電変換材料と従来の単体Ｓｉを比較すると、変調ドープ構造のＺＴは約２倍大きなＺＴを得ることが可能となる。さらに、変調ドープ型熱電変換材料では粒径が小さくなるにつれてＺＴは増大し、粒径５ｎｍにおいては１１００ＫでＺＴ＝４以上を示すことが可能である。   FIG. 6A shows an example of temperature dependence of ZT when the crystal grain size is changed when Si is selected as the parent phase 10 of the modulation-doped thermoelectric conversion material. Regardless of the presence of the modulation doping structure, ZT increases with temperature at any crystal grain size. When a modulation doped thermoelectric conversion material having a particle size of 100 nm is compared with a conventional simple substance Si, it is possible to obtain a ZT having a modulation doping structure that is approximately twice as large. Furthermore, in the modulation-doped thermoelectric conversion material, ZT increases as the particle size decreases, and at a particle size of 5 nm, ZT = 4 or more can be exhibited at 1100 K.

図６Ｂは、変調ドープ型熱電変換材料の母相１０にＧｅを選択した場合において、結晶粒径を変化させたときのＺＴの温度依存性の一例を示す。母相１０としてＧｅを用いた場合も前述のＳｉの場合と同様に、変調ドープ構造を適用し粒径を小さくするにつれてＺＴの向上が可能となる。   FIG. 6B shows an example of the temperature dependence of ZT when the crystal grain size is changed when Ge is selected as the parent phase 10 of the modulation-doped thermoelectric conversion material. Even when Ge is used as the parent phase 10, ZT can be improved as the grain size is reduced by applying a modulation dope structure as in the case of Si described above.

以上、本実施例によれば、比抵抗低減と熱伝導率低減とが両立可能な熱電変換材料を提供することができる。また、比抵抗低減と熱伝導率低減とを両立させることにより、材料性能指数ＺＴを改善することができる。   As described above, according to this example, it is possible to provide a thermoelectric conversion material that can achieve both a reduction in specific resistance and a reduction in thermal conductivity. Moreover, the material performance index ZT can be improved by making both the specific resistance reduction and the thermal conductivity reduction compatible.

本発明の第２の実施例に係る熱電変換素子ついて、図７を用いて説明する。なお、実施例１に記載され本実施例に未記載の事項は特段の事情がない限り本実施例にも適用することができる。   A thermoelectric conversion element according to a second embodiment of the present invention will be described with reference to FIG. Note that the matters described in the first embodiment and not described in the present embodiment can be applied to the present embodiment as long as there is no special circumstances.

図７は、本実施例に係る熱電変換素子の構成例を示す模式図である。この熱電変換素子は、実施例１に記載した変調ドープ型熱電材料を用い、一対のｐ型の変調ドープ型熱電変換材料２００とｎ型の変調ドープ型熱電変換材料２０１とそれらを接続する上部の電極１００、さらにｐ型変調ドープ型熱電変換材料及びｎ型変調ドープ型熱電変換材料に接続する下部の電極１０１から構成される。ここで、本熱電変換素子の上部（電極１００側）に高い温度ＴＨ、下部（電極１０１側）にＴＨよりも低い温度ＴＬが与えられ、本熱電変換素子の両変調ドープ型熱電変換材料に上部電極１００側から下部電極１０１側に温度差ΔＴ（＝ＴＨ−ＴＬ）の勾配がかかったときに変調ドープ型熱電変換材料でゼーベック効果によって発生する電気を電力（電圧あるいは電流）として下部電極１０１（右側）と下部電極１０１（左側）との間から取り出す構成である。FIG. 7 is a schematic diagram illustrating a configuration example of the thermoelectric conversion element according to the present embodiment. This thermoelectric conversion element uses the modulation-doped thermoelectric material described in Example 1, and uses a pair of p-type modulation-doped thermoelectric conversion material 200 and n-type modulation-doped thermoelectric conversion material 201 and an upper portion connecting them. The electrode 100 further includes a lower electrode 101 connected to a p-type modulation doped thermoelectric conversion material and an n-type modulation doped thermoelectric conversion material. Here, a high temperature T H is applied to the upper part (electrode 100 side) of the thermoelectric conversion element, and a temperature TL lower than T H is applied to the lower part (electrode 101 side), and both modulation doped thermoelectric conversion of the thermoelectric conversion element is performed. Electricity (voltage or current) generated by the Seebeck effect in the modulation-doped thermoelectric conversion material when the material is subjected to a gradient of temperature difference ΔT (= T H −T L ) from the upper electrode 100 side to the lower electrode 101 side As shown in FIG.

本構成において、例えばｐ型変調ドープ型熱電材料として母相にＳｉＢ、キャリア供給相にＧａＮＢ、またｎ型変調ドープ型熱電材料として母相にＳｉＰ、キャリア供給相にＧａＮＰを用いて熱源１１００Ｋと室温の温度差を印加したときに、最大３０％の変換効率を得ることが可能になる。   In this configuration, for example, the base phase is SiB as the p-type modulation doped thermoelectric material, the carrier supply phase is GANB, the base phase is SiP as the n-type modulation dope thermoelectric material, and the carrier supply phase is GANP. It is possible to obtain a conversion efficiency of 30% at the maximum when the temperature difference is applied.

なお、熱電変換素子としてはｐ型およびｎ型の両者に変調ドープ型熱電変換材料を用いることが好適であり、本実施例ではｐ型およびｎ型の熱電変換材料の両者に変調ドープ構造を有する材料を用いた。但し、ｐ型およびｎ型の熱電変換材料の内の少なくとも一方を変調ドープ構造とすることにより、従来の熱電変換素子よりも良好な特性を得ることができる。   As the thermoelectric conversion element, it is preferable to use a modulation doped thermoelectric conversion material for both p-type and n-type. In this embodiment, both the p-type and n-type thermoelectric conversion materials have a modulation dope structure. Material was used. However, when at least one of the p-type and n-type thermoelectric conversion materials has a modulation dope structure, better characteristics than those of conventional thermoelectric conversion elements can be obtained.

以上、本実施例によれば、実施例１で示した熱電変換材料を用いることにより熱電変換効率の高い熱電変換素子を提供することができる。   As described above, according to this example, a thermoelectric conversion element having high thermoelectric conversion efficiency can be provided by using the thermoelectric conversion material shown in Example 1.

本発明の第３の実施例に係る熱電変換モジュールについて、図８を用いて説明する。なお、実施例１又は２に記載され本実施例に未記載の事項は特段の事情がない限り本実施例にも適用することができる。   A thermoelectric conversion module according to a third embodiment of the present invention will be described with reference to FIG. Note that matters described in the first or second embodiment but not described in the present embodiment can also be applied to the present embodiment unless there are special circumstances.

図８は、本実施例に係る熱電変換モジュールの斜視図であり、図７に示した熱電変換素子を複数個平面状に配置して構成されている。図７に示した上部電極１００および下部電極１０１が、各熱電変換素子を接続する電極となり、ｐ型変調ドープ型熱電変換材料２００とｎ型変調ドープ型熱電変換材料２０１がそれぞれ交互に接続されるように配置されている。Ｌは上部電極と下部電極との間の距離（熱電変換材料の高さ）を示す。ここで、実施例２で述べた熱源１１００Ｋと室温の温度差を上部電極１００と下部電極１０１に印加したときに本実施例の熱電変換モジュールでは最大３０％の変換効率を得ることが可能となる。   FIG. 8 is a perspective view of the thermoelectric conversion module according to the present embodiment, and is configured by arranging a plurality of thermoelectric conversion elements shown in FIG. 7 in a planar shape. The upper electrode 100 and the lower electrode 101 shown in FIG. 7 serve as electrodes for connecting the thermoelectric conversion elements, and the p-type modulation doped thermoelectric conversion material 200 and the n-type modulation doped thermoelectric conversion material 201 are alternately connected to each other. Are arranged as follows. L represents the distance between the upper electrode and the lower electrode (the height of the thermoelectric conversion material). Here, when the temperature difference between the heat source 1100K and the room temperature described in the second embodiment is applied to the upper electrode 100 and the lower electrode 101, the thermoelectric conversion module of the present embodiment can obtain a conversion efficiency of 30% at the maximum. .

なお、熱電変換素子としてはｐ型およびｎ型の両者に変調ドープ型熱電変換材料を用いることが好適であり、本実施例ではｐ型およびｎ型の熱電変換材料の両者に変調ドープ構造を有する材料を用いた。但し、ｐ型およびｎ型の熱電変換材料の内の少なくとも一方を変調ドープ構造とすることにより、従来の熱電変換素子よりも良好な特性を得ることができる。   As the thermoelectric conversion element, it is preferable to use a modulation doped thermoelectric conversion material for both p-type and n-type. In this embodiment, both the p-type and n-type thermoelectric conversion materials have a modulation dope structure. Material was used. However, when at least one of the p-type and n-type thermoelectric conversion materials has a modulation dope structure, better characteristics than those of conventional thermoelectric conversion elements can be obtained.

以上、本実施例によれば、実施例１で示した熱電変換材料と実施例２で示した熱電変換素子構造を用いることにより熱電変換効率の高い熱電変換素子を提供することができる。   As described above, according to this example, a thermoelectric conversion element having high thermoelectric conversion efficiency can be provided by using the thermoelectric conversion material shown in Example 1 and the thermoelectric conversion element structure shown in Example 2.

なお、本発明は上記した実施例に限定されるものではなく、様々な変形例が含まれる。例えば、上記した実施例は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも説明した全ての構成を備えるものに限定されるものではない。また、ある実施例の構成の一部を他の実施例の構成に置き換えることも可能であり、また、ある実施例の構成に他の実施例の構成を加えることも可能である。また、各実施例の構成の一部について、他の構成の追加・削除・置換をすることが可能である。   In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

１０…母相、１５…母相とキャリア供給相との界面、２０…キャリア供給相、２１…変調ドープ構造を有さない熱電変換材料、３０…イオン化不純物、４０…キャリア、４１…キャリア、１００…上部電極、１０１…下部電極、２００…ｐ型変調ドープ型熱電変換材料、２０１…ｎ型変調ドープ熱電変換材料、３０１…イオン化不純物、４０１…キャリア、４１１…キャリア。 DESCRIPTION OF SYMBOLS 10 ... Mother phase, 15 ... Interface between mother phase and carrier supply phase, 20 ... Carrier supply phase, 21 ... Thermoelectric conversion material having no modulation dope structure, 30 ... Ionized impurities, 40 ... Carrier, 41 ... Carrier, 100 ... upper electrode, 101 ... lower electrode, 200 ... p-type modulation doped thermoelectric conversion material, 201 ... n-type modulation doped thermoelectric conversion material, 301 ... ionized impurities, 401 ... carrier, 411 ... carrier.

Claims (9)

イオン化不純物を含むキャリア供給相からなる第１粒子と、
前記キャリア供給相よりもイオン化不純物濃度が低い母相からなる第２粒子と、を含む熱電変換材料であって、
前記第１粒子と前記第２粒子の粒径は、共に１００ｎｍ以下であり、
前記キャリア供給相に含まれた不純物により生じるキャリアは、前記母相内へ注入され前記母相内を伝導するものであることを特徴とする熱電変換材料。First particles comprising a carrier supply phase containing ionized impurities;
A thermoelectric conversion material comprising: second particles composed of a parent phase having a lower ionized impurity concentration than the carrier supply phase,
The particle diameters of the first particles and the second particles are both 100 nm or less,
A carrier generated by impurities contained in the carrier supply phase is injected into the mother phase and conducts in the mother phase. 請求項１に記載の熱電変換材料において、
前記キャリア供給相は、
前記母相がＳｉで構成される場合には、Ｓｉ、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＳｉδ、ＺｒＴｉδ、ＨｆＳｉδ、ＶＳｉδ、ＭｏＳｉδ、ＷＳｉδ、の何れかで構成され、
前記母相がＧｅで構成される場合には、Ｓｉ、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＧｅδ、ＺｒＧｅδ、ＨｆＧｅδ、ＶＧｅδ、ＭｏＧｅδ、ＷＧｅδのいずれかで構成されることを特徴する熱電変換材料。In the thermoelectric conversion material according to claim 1,
The carrier supply phase is
When the parent phase is composed of Si, it is composed of any of Si, Ge, SiC, GaN, SrTiO 3 , TiSi δ , ZrTi δ , HfSi δ , VSi δ , MoSi δ , WSi δ ,
When the matrix is composed of Ge, it is composed of any one of Si, Ge, SiC, GaN, SrTiO 3 , TiGe δ , ZrGe δ , HfGe δ , VGe δ , MoGe δ , and WGe δ. Characteristic thermoelectric conversion material. 請求項１に記載の熱電変換材料において、
前記母相と前記キャリア供給相の混合比は、それらの物質が共晶や共析など相互に固溶しない比率であることを特徴とする熱電変換材料。In the thermoelectric conversion material according to claim 1,
The thermoelectric conversion material characterized in that the mixing ratio of the matrix phase and the carrier supply phase is such a ratio that these substances do not form a solid solution such as eutectic or eutectoid. 電力を取り出すための電極で接続されたｎ型熱電変換材料とｐ型熱電変換材料との一対で構成され、ゼーベック効果を用いて発電する熱電変換素子において、
前記ｎ型およびｐ型熱電変換材料の少なくとも一者は、
イオン化不純物を含むキャリア供給相からなる第１粒子と、
前記キャリア供給相よりもイオン化不純物濃度が低い母相からなる第２粒子と、を含み、
前記第１粒子と前記第２粒子の粒径は、共に１００ｎｍ以下であり、
前記キャリア供給相に含まれた不純物により生じるキャリアは、前記母相内へ注入され前記母相内を伝導するものであることを特徴とする熱電変換素子。In a thermoelectric conversion element configured by a pair of an n-type thermoelectric conversion material and a p-type thermoelectric conversion material connected by an electrode for taking out electric power and generating electric power using the Seebeck effect,
At least one of the n-type and p-type thermoelectric conversion materials is:
First particles comprising a carrier supply phase containing ionized impurities;
Second particles composed of a parent phase having a lower ionized impurity concentration than the carrier supply phase,
The particle diameters of the first particles and the second particles are both 100 nm or less,
A carrier generated by impurities contained in the carrier supply phase is injected into the mother phase and conducts in the mother phase. 請求項４に記載の熱電変換素子において、
前記キャリア供給相は、
前記母相がＳｉで構成される場合には、Ｓｉ、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＳｉδ、ＺｒＴｉδ、ＨｆＳｉδ、ＶＳｉδ、ＭｏＳｉδ、ＷＳｉδ、の何れかで構成され、
前記母相がＧｅで構成される場合には、Ｓｉ、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＧｅδ、ＺｒＧｅδ、ＨｆＧｅδ、ＶＧｅδ、ＭｏＧｅδ、ＷＧｅδのいずれかで構成されることを特徴する熱電変換素子。In the thermoelectric conversion element according to claim 4,
The carrier supply phase is
When the parent phase is composed of Si, it is composed of any of Si, Ge, SiC, GaN, SrTiO 3 , TiSi δ , ZrTi δ , HfSi δ , VSi δ , MoSi δ , WSi δ ,
When the matrix is composed of Ge, it is composed of any one of Si, Ge, SiC, GaN, SrTiO 3 , TiGe δ , ZrGe δ , HfGe δ , VGe δ , MoGe δ , and WGe δ. Characteristic thermoelectric conversion element. 請求項４に記載の熱電変換素子において、
前記母相と前記キャリア供給相の混合比は、それらの物質が共晶や共析など相互に固溶しない比率であることを特徴とする熱電変換素子。In the thermoelectric conversion element according to claim 4,
The thermoelectric conversion element according to claim 1, wherein a mixing ratio of the matrix phase and the carrier supply phase is a ratio in which these substances do not form solid solutions such as eutectic or eutectoid. 電力を取り出すための電極で接続されたｎ型熱電変換材料とｐ型熱電変換材料の複数対で構成され、ゼーベック効果を用いて発電する熱電変換モジュールにおいて、
前記ｎ型およびｐ型熱電変換材料の少なくとも一者は、
イオン化不純物を含むキャリア供給相からなる第１粒子と、
前記キャリア供給相よりもイオン化不純物濃度が低い母相からなる第２粒子と、を含み、
前記第１粒子と前記第２粒子の粒径は、共に１００ｎｍ以下であり、
前記キャリア供給相に含まれた不純物により生じるキャリアは、前記母相内へ注入され前記母相内を伝導するものであることを特徴とする熱電変換モジュール。In a thermoelectric conversion module configured by a plurality of pairs of an n-type thermoelectric conversion material and a p-type thermoelectric conversion material connected by an electrode for taking out electric power, and generating electric power using the Seebeck effect,
At least one of the n-type and p-type thermoelectric conversion materials is:
First particles comprising a carrier supply phase containing ionized impurities;
Second particles composed of a parent phase having a lower ionized impurity concentration than the carrier supply phase,
The particle diameters of the first particles and the second particles are both 100 nm or less,
Carriers generated by impurities contained in the carrier supply phase are injected into the mother phase and conducted in the mother phase. 請求項７に記載の熱電変換モジュールにおいて
前記キャリア供給相は、
前記母相がＳｉで構成される場合には、Ｓｉ、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＳｉδ、ＺｒＴｉδ、ＨｆＳｉδ、ＶＳｉδ、ＭｏＳｉδ、ＷＳｉδ、の何れかで構成され、
前記母相がＧｅで構成される場合には、Ｓｉ、Ｇｅ、ＳｉＣ、ＧａＮ、ＳｒＴｉＯ３、ＴｉＧｅδ、ＺｒＧｅδ、ＨｆＧｅδ、ＶＧｅδ、ＭｏＧｅδ、ＷＧｅδのいずれかで構成されることを特徴する熱電変換モジュール。The thermoelectric conversion module according to claim 7, wherein the carrier supply phase is
When the parent phase is composed of Si, it is composed of any of Si, Ge, SiC, GaN, SrTiO 3 , TiSi δ , ZrTi δ , HfSi δ , VSi δ , MoSi δ , WSi δ ,
When the matrix is composed of Ge, it is composed of any one of Si, Ge, SiC, GaN, SrTiO 3 , TiGe δ , ZrGe δ , HfGe δ , VGe δ , MoGe δ , and WGe δ. Characteristic thermoelectric conversion module. 請求項７に記載の熱電変換モジュールにおいて、
前記母相と前記キャリア供給相の混合比は、それらの物質が共晶や共析など相互に固溶しない比率であることを特徴とする熱電変換モジュール。The thermoelectric conversion module according to claim 7,
The thermoelectric conversion module according to claim 1, wherein a mixing ratio of the matrix phase and the carrier supply phase is a ratio in which these substances do not form a solid solution such as eutectic or eutectoid.
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