JP6024598B2 - Thermoelectric generator - Google Patents

Description

  The present invention relates to a thermoelectric power generation element that converts thermal energy into electrical energy.

  As a power generation element that converts thermal energy into electrical energy, there is a thermoelectron power generation element that generates electromotive force by utilizing thermionic emission. For example, Patent Document 1 discloses an example of a thermionic power generation element in which an emitter part and a collector part are arranged with a predetermined gap therebetween. This thermoelectron power generation element is configured such that when the emitter section is heated, thermoelectrons are emitted from the emitter section and collected by the collector section. And in the state which connected the load between the emitter part and the collector part, electric power can be supplied to a load by the thermoelectron which reached | attained the collector part moving to an emitter part via a load.

  Further, the thermoelectric power generation element of Patent Document 1 is configured such that an interval between the two can be adjusted by disposing an adjusting member made of an insulator between the emitter part and the collector part.

JP 2008-228387 A

  However, when the adjusting member is arranged between the emitter and the collector as in Patent Document 1, a potential difference generated between the emitter and the collector is applied to the adjusting member, and therefore, via the surface of the adjusting member. There is a risk of current leakage. Therefore, when using an adjustment member, there exists a problem that the electric power generation efficiency of a thermoelectric power generation element falls.

  The present invention has been made in view of such a background, and intends to provide a thermionic power generation element having high power generation efficiency.

One aspect of the present invention is an emitter substrate made of a high resistance material;
An emitter formed on the surface of the emitter substrate for generating thermionic electrons;
A collector substrate made of a high-resistance material disposed opposite to the emitter substrate;
A collector that is formed on the surface of the collector substrate and collects the thermal electrons;
At least one of the emitter substrate and the collector substrate has a spacer portion protruding toward the other,
The tip of the spacer portion is in the thermoelectron power generation element, which is in contact with the substrate facing the substrate from which the spacer portion protrudes, of the emitter substrate and the collector substrate .

  The thermoelectric power generation element has an emitter substrate and a collector substrate made of a high resistance material, and is configured such that the emitter substrate and the collector substrate are in contact with each other at the end of the spacer portion. Therefore, the potential difference generated between the emitter and the collector is not applied between the emitter substrate and the collector substrate. As a result, the leak current flowing through the spacer portion can be reduced.

  As described above, the thermoelectric power generation element has high power generation efficiency.

FIG. 3 is a top view of the thermoelectric generator in Example 1. FIG. 3 is a top view of an emitter substrate in which an emitter is formed on the surface in Example 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 3 is an explanatory view of a wafer in which a SiO ₂ film is formed on the entire surface in the manufacturing process of the thermoelectric generator of Example 1. FIG. 3 is an explanatory diagram of a wafer in which a region for forming a spacer portion is patterned in the manufacturing process of the thermoelectric generator of Example 1. FIG. 3 is an explanatory diagram of a wafer from which a SiO ₂ film other than a region for forming a spacer portion has been removed in the manufacturing process of the thermoelectric generation element of Example 1. FIG. 3 is an explanatory view of a wafer in which a spacer portion is formed by ICP etching in the manufacturing process of the thermoelectric generator of Example 1. Example 1 An explanatory view of a wafer in which an emitter is selectively formed using a SiO ₂ film as a mask in a production process of a thermoelectric power generation element. Sectional drawing of the thermoelectric power generation element which has a reinforcement convex part in Example 2 (sectional drawing corresponded in FIG. 3). Sectional drawing in Example 2 which shows the state in which the thermoelectric power generation element curved (sectional drawing equivalent to FIG. 3). FIG. 6 is an explanatory view of a wafer in which a region other than a region where a spacer portion is formed by ICP etching is depressed in a manufacturing process of a thermoelectric power generation element of Example 2. FIG. 6 is an explanatory diagram of a wafer obtained by patterning a region where a spacer portion and a reinforcing convex portion are formed in the manufacturing process of the thermoelectric power generation element of Example 2. FIG. 5 is an explanatory view of a wafer from which a SiO ₂ film other than a region where a spacer portion and a reinforcing convex portion are formed is removed in the manufacturing process of the thermoelectric generation element of Example 2. FIG. 6 is an explanatory view of a wafer in which a spacer portion and a reinforcing convex portion are formed by ICP etching in the manufacturing process of the thermoelectric generator of Example 2. FIG. 6 is an explanatory view of a wafer in which emitters are selectively formed using a SiO ₂ film as a mask in the manufacturing process of the thermoelectric generator of Example 2. FIG. 4 is a top view of a thermoelectric power generation element manufactured using a diamond semiconductor substrate in Example 3. FIG. 6 is a top view of an emitter substrate having an emitter formed on the surface in Example 3. XVIII-XVIII arrow directional cross-sectional view of FIG. Sectional drawing of the thermoelectron power generation element which formed the connection part in the back surface of the emitter substrate and the collector substrate in the modification 1 (sectional drawing corresponded in FIG. 3). Sectional drawing of the thermoelectric power generation element which formed the emitter and the collector in the area | region except the reinforcement convex part and a spacer part in the modification 2 (sectional drawing corresponded in FIG. 3). Sectional drawing of the thermoelectron power generation element which does not have an emitter and a collector in the part which faces a reinforcement convex part in the modification 2 (sectional drawing corresponded in FIG. 3).

  In the above-mentioned thermionic power generation element, the high resistance material constituting the emitter substrate and the collector substrate refers to a material that behaves as an insulator in the range of potential difference that can occur between the emitter and the collector, such as ceramics such as oxides and nitrides. It is a concept that includes semiconductors. As the semiconductor, for example, diamond, Si, GaN, SiC, BN, GaAs, InP, or the like can be used. Further, the emitter substrate and the collector substrate may be made of the same material or different materials.

  Further, at least one of the emitter substrate and the collector substrate has a reinforcing convex portion protruding toward the other, and the tip of the reinforcing convex portion among the emitter, the collector, the emitter substrate, and the collector substrate. A gap is formed between the member facing the surface and the tip of the reinforcing convex portion, and the tip of the reinforcing convex portion and the member facing the surface in a state where the emitter substrate or the collector substrate is curved And may be configured to be able to contact each other.

  That is, the reinforcing convex portion is erected on either or both of the emitter substrate and the collector substrate, and in a state where the emitter substrate and the collector substrate are not curved, the reinforcing convex portion is opposed to the tip. You may be comprised so that the member to do may not contact | abut. In this case, there is no possibility of leakage current flowing through the surface of the reinforcing projection. Further, the heat of the emitter is not conducted to the collector through the reinforcing projection. Therefore, the thermoelectric power generation element tends to have higher power generation efficiency.

  Further, when the reinforcing convex portion is bent due to at least one of the emitter substrate or the collector substrate due to a temperature difference or a difference in thermal expansion coefficient between them, an external force, or the like, You may be comprised so that the member which faces this may contact | abut. The reinforcing convex portion configured in this manner has a function of preventing the emitter and collector from coming into contact when the emitter substrate or the like is curved. Therefore, the thermoelectric power generation element having the reinforcing convex portion is less likely to short-circuit the emitter and the collector, and tends to be more reliable.

  As described above, the thermoelectric power generation element can further improve the characteristics of both power generation efficiency and reliability by having the reinforcing protrusion.

Example 1
Examples of the thermoelectric generator will be described with reference to FIGS. As shown in FIG. 3, a thermionic power generation element 1 includes an emitter substrate 2, an emitter 3 that is formed on a surface 21 of the emitter substrate 2, and generates thermoelectrons, and a collector substrate that is disposed to face the emitter substrate 2. 4 and a collector 5 which is formed on the surface 41 of the collector substrate 4 and collects thermoelectrons. The emitter substrate 2 and the collector substrate 4 are made of an intrinsic silicon semiconductor which is a high resistance material.

  As shown in FIGS. 2 and 3, the emitter substrate 2 has a plurality of spacer portions 22 (22 a, 22 b) that protrude toward the collector substrate 4. Similarly, the collector substrate 4 has a plurality of spacer portions 42 (42a, 42b) protruding toward the emitter substrate 2 as shown in FIG. The emitter substrate 2 and the collector substrate 4 are in contact with each other at the tips of the spacer portions 22 and 42.

  Hereinafter, the thermoelectric generator 1 will be described in detail. As shown in FIG. 1, the thermoelectric generator 1 has a rectangular shape when viewed from the direction in which the emitter substrate 2 and the collector substrate 4 overlap. In the following, the direction in which the emitter substrate 2 and the collector substrate 4 face each other is referred to as an “overlapping direction Z”. For convenience, when the thermoelectric generator 1 is viewed from the overlapping direction Z, the direction in which the short sides face each other is called “vertical direction X”, and the direction in which the long sides face each other is called “lateral direction Y”.

As shown in FIG. 1, the thermoelectric generator 1 has a pair of connecting portions 12 (12e, 12c) that connect the emitter 3 and the collector 5 to a load on one side 11 in the longitudinal direction X. . The connection part 12e electrically connected to the emitter 3 protrudes outward in the vertical direction X from one end 111 of the side part 11, and has a substantially rectangular shape when viewed in the overlapping direction Z. The connecting portion 12e is composed of an emitter substrate 2 and an emitter 3 extending in the vertical direction X.


Similarly, the connection part 12c electrically connected to the collector 5 protrudes outward in the vertical direction X from the other end 112 of the side part 11, and has a substantially rectangular shape when viewed in the overlapping direction Z. ing. The connecting portion 12 c is composed of a collector substrate 4 and a collector 5 extending in the vertical direction X.

  As shown in FIG. 2, a pair of spacer portions 22 a are erected on both side edges in the vertical direction X of the emitter substrate 2. As shown in FIG. 2, the pair of spacer portions 22 a have a rectangular shape that is long in the lateral direction Y when viewed from the overlapping direction Z. A plurality of spacer portions 22b having a square shape when viewed from the overlapping direction Z are formed between the pair of spacer portions 22a.

  As shown in FIGS. 1 and 3, the spacer portion 42 formed on the collector substrate 4 is formed at a position in contact with the spacer portion 22 of the emitter substrate 2 in a state where the spacer portion 42 is overlapped with the emitter substrate 2. That is, a pair of spacer portions 42a having a rectangular shape as viewed from the overlapping direction Z are provided on both side edges in the longitudinal direction X of the collector substrate 4, and the overlapping direction is between the pair of spacer portions 42a. A plurality of spacer portions 42b having a square shape as viewed from Z are formed. In the state where the emitter substrate 2 and the collector substrate 4 are overlapped, the spacer portion 42 is a position where the rectangular spacer portions 22a and 42a contact each other and the square spacer portions 22b and 42b contact each other. Is arranged. In addition, the height of the spacer parts 22 and 42 in this example is 10-15 micrometers, and let all be the same height.

  The emitter 3 is made of an n-type diamond semiconductor whose surface 31 is terminated with hydrogen. The emitter 3 is formed so as to cover a region excluding the spacer portion 22 on the surface 21 of the emitter substrate 2 as shown in FIGS. The thickness of the emitter 3 in this example is about 0.1 to 1 μm.

  The collector 5 is made of an n-type diamond semiconductor having a dopant concentration lower than that of the emitter 3. Further, as shown in FIG. 3, the collector 5 is formed so as to cover a region on the surface 41 of the collector substrate 4 excluding the spacer portion 42. The thickness of the collector 5 in this example is about 0.1 to 1 μm.

  As shown in FIG. 3, the surface 31 of the emitter 3 and the surface 51 of the collector 5 are parallel to each other, and both face each other with a gap in the overlapping direction Z.

  Next, a method for manufacturing the thermoelectric generator 1 will be described with reference to FIGS. Note that the manufacturing method described below is an example, and the manufacturing method can be performed by other methods.

<Emitter substrate 2 and emitter 3>
As shown in FIG. 4, an SiO ₂ film 61 that functions as an etching mask is formed on the surface of a wafer 6 made of an intrinsic silicon semiconductor by a thermal CVD method. Next, as shown in FIG. 5, a resist 62 is applied on the SiO ₂ film 61 and patterned, and a region where the spacer portion 22 is to be formed is covered with the resist 62. After the patterning, wet etching is performed using hydrofluoric acid to remove the SiO ₂ film 61 exposed on the surface. Thereby, as shown in FIG. 6, the SiO ₂ film 61 and the resist 62 are laminated only in the region where the spacer portion 22 is formed.

Next, the wafer 6 is etched while removing the resist 62 on the wafer 6 by performing ICP dry etching. At this time, since the SiO ₂ film 61 left on the wafer 6 functions as an etching mask, as shown in FIG. 7, the region covered with the SiO ₂ film 61 is not etched and protrudes relative to the surroundings. To do. As described above, the spacer portion 22 can be formed.

After the spacer portion 22 is formed, the emitter 3 made of an n-type diamond semiconductor is formed on the wafer 6 using a microwave plasma CVD method with the SiO ₂ film 61 left at the tip of the spacer portion 22. At this time, the emitter 3 is not formed on the SiO ₂ film 61 but is selectively formed in a region where the silicon semiconductor is exposed, that is, a region other than the spacer portion 22 (see FIG. 8). The conditions for the microwave plasma CVD method are as follows.

・ CH ₄ gas flow rate 4sccm
・ H ₂ gas flow rate 400sccm
・ N ₂ gas flow rate 40sccm
・ Microwave output 800W
・ Vacuum degree in the device 100 Torr

After the emitter 3 is formed on the emitter substrate 2, wet etching is performed using hydrofluoric acid to remove the SiO ₂ film 61 remaining at the tip of the spacer portion 22. Thereafter, the wafer 6 is cut and divided for each element to obtain the emitter substrate 2 on which the emitter 3 is formed.

<Collector substrate 4 and collector 5>
The collector substrate 4 and the collector 5 can be manufactured by substantially the same procedure as that for manufacturing the emitter substrate 2 and the emitter 3 described above.

  The emitter substrate 2 and the collector substrate 4 obtained by the above method are joined in a state where the tip of the spacer portion 22 and the tip of the spacer portion 42 are in contact with each other. Thereby, the thermoelectric power generation element 1 shown in FIGS. 1 to 3 can be obtained.

  The thermoelectric generator 1 configured as described above can be used as follows, for example. First, a load is connected between the pair of connection portions 12. Then, the space between the emitter 3 and the collector 5 is decompressed, and the emitter substrate 2 is heated in this state. Thereby, thermoelectrons are emitted from the emitter 3 heated together with the emitter substrate 2 and collected by the collector 5. Then, the thermoelectrons collected in the collector 5 flow out from the connecting portion 12c on the collector substrate 4 side, pass through the load, and return to the emitter 3.

  Next, the function and effect of the thermoelectric generator 1 will be described. As shown in FIG. 3, the thermoelectric generator 1 is configured such that the emitter substrate 2 and the collector substrate 4 are in contact with each other at the tips of the spacer portions 22 and 42. Therefore, a potential difference generated between the emitter 3 and the collector 5 is not applied between the emitter substrate 2 and the collector substrate 4. As a result, the leakage current flowing through the spacer portions 22 and 42 can be reduced.

  Further, the surface 31 of the emitter 3 and the surface 51 of the collector 5 are parallel to each other. Therefore, it becomes easy to maintain the space | interval between the emitter 3 and the collector 5 at the magnitude | size which a thermoelectron moves easily. As a result, the thermoelectric power generation element 1 can easily obtain a stable output.

  Further, the surface 31 of the emitter 3 and the surface 51 of the collector 5 face each other through a gap. Therefore, the collector 5 can collect the thermal electrons emitted from the emitter 3 more efficiently. As a result, the power generation efficiency of the thermoelectric power generation element 1 can be further improved.

  The emitter 3 is composed of an n-type diamond semiconductor whose surface 31 is terminated with hydrogen. The diamond semiconductor whose surface 31 is hydrogen-terminated has a so-called negative electron affinity (NEA) in which the vacuum level is at an energy level lower than the lower end of the valence band. In such a state, electrons excited by heat from the conduction band or the impurity level can transition to the vacuum level without requiring additional energy, so that the thermal electrons are easily emitted from the surface 31. As a result, thermoelectrons are more easily emitted from the emitter 3, and the power generation efficiency of the thermoelectron power generation element 1 can be further improved.

  The collector 5 is made of an n-type diamond semiconductor having a dopant concentration lower than that of the emitter 3. Therefore, the number of electrons thermally excited in the collector 5 is sufficiently smaller than that of the emitter 3. As a result, the number of thermoelectrons emitted from the collector 5 toward the emitter 3 is sufficiently smaller than the number of thermoelectrons emitted from the emitter 3 toward the collector 5. That is, the thermionic power generation element 1 can suppress so-called back emission in which thermoelectrons move from the collector 5 to the emitter 3 and can further improve power generation efficiency.

  As described above, the thermoelectric power generation element 1 has high power generation efficiency.

(Example 2)
In this example, as shown in FIGS. 9 to 15, a plurality of reinforcing convex portions 23 and 43 are provided instead of the spacer portions 22 b and 42 b in the thermoelectric power generation element 1 of the first embodiment. As shown in FIG. 9, the emitter substrate 202 in the thermoelectric generator 102 of this example has a pair of spacer portions 22a on both side edges in the vertical direction X, as in the first embodiment. In addition, a plurality of reinforcing protrusions 23 protruding toward the collector substrate 402 are provided between the pair of spacer portions 22a.

  Similarly, the collector substrate 402 has a pair of spacer portions 42 a at both side edges in the vertical direction X. In addition, a plurality of reinforcing convex portions 43 projecting toward the emitter substrate 202 are provided between the pair of spacer portions 42a.

  The reinforcing convex portion 23 of the emitter substrate 202 and the reinforcing convex portion 43 of the collector substrate 402 are arranged at positions facing each other when the emitter substrate 202 and the collector substrate 402 are overlapped. Further, as shown in FIG. 9, the tip of the reinforcing convex portion 23 of the emitter substrate 202 and the tip of the reinforcing convex portion 43 of the collector substrate 402 face each other, and a gap is formed between them. As shown in FIG. 10, the reinforcing convex portion 23 and the reinforcing convex portion 43 can be brought into contact with each other in a state where the emitter substrate 202 or the collector substrate 402 is curved. In addition, the height of the reinforcement convex parts 23 and 43 in this example is about 1-2 micrometers lower than the spacer parts 22 and 42.

  Next, a method for manufacturing the thermoelectric generator 102 will be described with reference to FIGS. In addition, the manufacturing method demonstrated below is an example and can also be manufactured by methods other than this.

<Emitter substrate 202 and emitter 3>
A SiO ₂ film 61 functioning as an etching mask is formed on the surface of the wafer 6 made of an intrinsic silicon semiconductor by a thermal CVD method. Next, a resist is applied on the SiO ₂ film 61 and patterned to cover the regions where the pair of spacer portions 22a are to be formed. After the patterning, wet etching is performed using hydrofluoric acid to remove the SiO ₂ film 61 exposed on the surface. Next, ICP dry etching is performed to etch the silicon semiconductor while removing the resist on the wafer 6. Thereby, as shown in FIG. 11, the area | region which forms the reinforcement convex part 23 is made about 1-2 micrometers lower than the area | region which forms the spacer part 22a. This difference in height corresponds to the difference in height between the spacer portion 22a and the reinforcing protrusion 23 in a state where the emitter substrate 202 is completed.

Next, after removing the SiO ₂ film 61 remaining at the tip of the spacer portion 22 a, the SiO ₂ film 63 is formed again on the entire surface of the wafer 6. Thereafter, a resist 64 is applied on the SiO ₂ film 63 and patterned, and both the regions where the pair of spacer portions 22a and the reinforcing convex portions 23 are formed are covered with the resist 64 as shown in FIG. After the patterning, wet etching is performed using hydrofluoric acid to remove the SiO ₂ film 63 exposed on the surface. As a result, as shown in FIG. 13, the SiO ₂ film 63 and the resist 64 are laminated only in the region where the spacer portion 22 a and the reinforcing convex portion 23 are formed.

  Next, the wafer 6 is etched while removing the resist 64 on the wafer 6 by performing ICP dry etching. Thereby, as shown in FIG. 14, a pair of spacer part 22a and the reinforcement convex part 23 are formed.

After forming the spacer portion 22a and the reinforcing convex portion 23, the emitter 3 made of an n-type diamond semiconductor is formed on the wafer 6 by using the microwave plasma CVD method with the SiO ₂ film 63 left at the tip thereof. . As a result, as shown in FIG. 15, a film is selectively formed in a region of the emitter substrate 202 excluding both the spacer portion 22 a and the reinforcing convex portion 23. The conditions of the microwave plasma CVD method are the same as those in the first embodiment.

After the emitter 3 is formed on the emitter substrate 202, wet etching is performed using hydrofluoric acid to remove the SiO ₂ film 63 remaining at the tips of the spacer portion 22a and the reinforcing convex portion 23. Thereafter, the wafer 6 is cut and divided into elements to obtain an emitter substrate 202 in a state where the emitter 3 is formed.

  Then, the emitter substrate 202 obtained by the above method and the collector substrate 402 obtained by substantially the same method are placed with the tip of the spacer portion 22 and the tip of the spacer portion 42 in contact with each other. Join. Thereby, the thermoelectric power generation element 102 shown in FIG. 9 can be obtained. Others are the same as in the first embodiment. Of the reference numerals used in FIGS. 9 to 15, the same reference numerals as those used in the first embodiment denote the same components as in the first embodiment unless otherwise specified.

  In the thermoelectric power generation element 102 of this example, the emitter substrate 202 and the collector substrate 402 have the reinforcing convex portion 23 and the reinforcing convex portion 43. Therefore, as described above, there is no leakage current or heat conduction through the reinforcing protrusions 23 and the reinforcing protrusions 43. When the emitter substrate 202 or the like is curved, the emitter 3 and the collector 5 are prevented from coming into contact with each other. As a result, the thermoelectric power generation element 102 can further improve both the characteristics of power generation efficiency and reliability. In addition, the same effects as those of the first embodiment can be achieved.

(Example 3)
This example is an example of a thermionic power generation element 103 using a diamond semiconductor as a material for the emitter substrate 203 and the collector substrate 403. The emitter substrate 203 and the collector substrate 403 in the thermoelectric power generation element 103 of this example are each formed of an intrinsic diamond semiconductor whose surfaces 21 and 41 in the thickness direction are (001) planes (see FIG. 18).

  As shown in FIGS. 17 and 18, the emitter substrate 203 has a plurality of emitter reinforcing protrusions 233 that are erected toward the collector substrate 403. The emitter reinforcing convex portion 233 has a substantially rectangular parallelepiped shape, and is formed with the crystal orientation aligned so that the top surface 24 becomes a (001) plane and the side surface 25 becomes a {110} plane.

  As shown in FIGS. 17 and 18, an emitter 3 made of an n-type diamond semiconductor and having a surface 111 of {111} is disposed on the base 26 of the emitter reinforcing projection 233.

  Similarly, the collector substrate 403 has a plurality of collector reinforcing projections 433 erected toward the emitter substrate 203 as shown in FIG. The collector reinforcing convex portion 433 has a substantially rectangular parallelepiped shape, and is formed with the crystal orientation aligned so that the top surface 44 becomes the (001) plane and the side surface 45 becomes the {110} plane, like the emitter reinforcing convex portion 233. Has been.

  As shown in FIG. 18, a collector 5 made of an n-type diamond semiconductor and having a surface 111 of {111} is disposed on the base 46 of the collector reinforcing projection 433.

  As shown in FIG. 18, the top surface 24 of the emitter reinforcing projection 233 faces the surface 41 of the collector substrate 403 through a gap, and the collector substrate 403 and the collector substrate 403 are curved in a state where the emitter substrate 203 or the collector substrate 403 is curved. It is comprised so that contact is possible. Similarly, the top surface 44 of the collector reinforcing projection 433 faces the surface 21 of the emitter substrate 203 via a gap, and can come into contact with the emitter substrate 203 in a state where the emitter substrate 203 or the collector substrate 403 is curved. It is configured.

  As shown in FIGS. 16 and 18, the emitter reinforcing protrusions 233 and the collector reinforcing protrusions 433 are alternately arranged so that the side surfaces 25 and the side surfaces 45 face each other. The surface 31 of the emitter 3 and the surface 51 of the collector 5 are configured to be parallel to each other between the adjacent emitter reinforcing convex portion 233 and collector reinforcing convex portion 433.

  Hereinafter, the thermoelectric power generation element 103 will be described in detail. As shown in FIG. 16, the thermoelectric generator 103 of this example has a substantially square shape when viewed in the overlapping direction Z. Further, the thermoelectric power generation element 103 includes a pair of connection portions 12 at one corner portion 13 when viewed from the overlapping direction Z.

  As shown in FIGS. 16 and 17, the spacer portion 223 of the emitter substrate 203 and the spacer portion 423 of the collector substrate 403 are erected on the outer peripheral edge when the thermoelectric generator 103 is viewed from the overlapping direction Z. . The spacer portions 223 and 423 have a square shape when viewed from the overlapping direction Z, and are arranged with the side surfaces directed in the <100> direction. That is, the side surfaces of the spacer portions 223 and 423 are constituted by {100} planes.

  As shown in FIG. 18, the spacer portion 223 of the emitter substrate 203 is in contact with the surface 41 of the collector substrate 403 in a state where the emitter substrate 203 and the collector substrate 403 are overlapped. Similarly, the spacer portion 423 of the collector substrate 403 is in contact with the surface 21 of the emitter substrate 203 in a state where the emitter substrate 203 and the collector substrate 403 are overlapped.

  As shown in FIG. 16, the emitter reinforcing convex portion 233 and the collector reinforcing convex portion 433 are arranged at the center when the thermoelectric generator 103 is viewed from the overlapping direction Z.

  As shown in FIGS. 16-18, the emitter reinforcement convex part 233 is exhibiting the substantially rectangular parallelepiped shape, and the longitudinal direction is arrange | positioned toward the <110> direction. Thereby, the side surface 25 of the emitter reinforcement convex part 233 is comprised from {110} surface. In this example, three emitter reinforcing convex portions 233 are arranged side by side in the direction perpendicular to the longitudinal direction.

  Further, as shown in FIGS. 16 and 18, the collector reinforcing convex portion 433 has a substantially rectangular parallelepiped shape, and the emitter reinforcing convex portions 233 adjacent to each other in a state where the emitter substrate 203 and the collector substrate 403 are overlapped with each other. It is comprised so that it may be arranged between. That is, the collector reinforcing convex part 433 has its longitudinal direction directed to the <1-10> direction on the collector substrate 403. Three collector reinforcing protrusions 433 are arranged side by side in the direction perpendicular to the longitudinal direction (not shown). Thereby, the side surface 45 of the collector reinforcing convex portion 433 is constituted by the {110} plane, and the side surface 25 of the emitter reinforcing convex portion 233 and the side surface 45 of the collector reinforcing convex portion 433 are arranged to face each other.

  As shown in FIG. 17, the emitter 3 is formed so as to surround the base portion 26 of the emitter reinforcing projection 233. As shown in FIG. 18, the emitter 3 has a right-angled isosceles triangular section with a corner portion 32 sandwiched between the side surface 25 of the emitter reinforcing projection 233 and the surface 21 of the emitter substrate 203 being a right angle. Yes. Further, the surface 31 of the emitter 3 is composed of {111} planes.

  Similarly, the collector 5 is formed so as to surround the base 46 of the collector reinforcing projection 433. As shown in FIG. 18, the collector 5 has a right-angled isosceles triangular section with a corner 52 sandwiched between the side surface 45 of the collector reinforcing projection 433 and the surface 41 of the collector substrate 403 being a right angle. ing. Further, the surface 51 of the collector 5 is composed of {111} planes.

  Further, as shown in FIG. 18, between the adjacent emitter reinforcing convex portion 233 and collector reinforcing convex portion 433, the surface 31 of the emitter 3 and the surface 51 of the collector 5 are parallel to each other, and both are Facing through a gap.

  The emitter substrate 203 and the collector substrate 403 have extraction electrodes that connect the emitter 3 and the collector 5 to an external circuit. The extraction electrode can be formed using a metal such as gold or aluminum. As shown in FIG. 17, the extraction electrode 27 disposed on the emitter substrate 203 extends from the connection portion 12 e toward the emitter 3. Similarly, the extraction electrode disposed on the collector substrate 403 extends from the connection portion 12c toward the collector 5 (not shown).

  Next, a method for manufacturing the thermoelectric generator 103 of this example will be described. The emitter substrate 203 and the collector substrate 403 can be formed by appropriately combining patterning and ICP etching with respect to an intrinsic diamond substrate whose surfaces 21 and 41 are (001) planes.

  The emitter 3 and the collector 5 can be formed by using a microwave plasma CVD method. As an example, the manufacturing conditions of the emitter 3 in this example are shown below.

・ CH ₄ gas flow rate 2sccm
・ H ₂ gas flow rate 400sccm
・ PH ₃ gas flow rate 2sccm
・ Microwave output 1000W
・ Vacuum degree in the device 30 Torr

  By using the above-described conditions, the emitter 3 is formed on the base portion 26 of the emitter reinforcing projection 233 by selective epitaxial growth. That is, under the above-mentioned conditions, the growth of {111} plane of diamond is superior to the growth of other crystal orientations. Therefore, in this case, the emitter 3 is <111 from the boundary 28 between the {110} plane constituting the side surface 25 of the emitter reinforcing projection 233 and the (001) plane constituting the surface 21 of the emitter substrate 203. > It becomes easy to grow selectively in the direction. As a result, the emitter 3 having the right isosceles triangular cross section as described above and the surface 31 being the {111} plane is formed.

  Similarly to the emitter 3, the collector 5 is formed on the base 46 of the collector reinforcing projection 433 by selective epitaxial growth.

  After forming the emitter 3 and the collector 5, the extraction electrode 27 is formed using a conventionally known method. Others are the same as in the first embodiment. Of the reference numerals used in FIGS. 16 to 18, the same reference numerals as those used in the first embodiment denote the same components as in the first embodiment unless otherwise specified.

  Next, the function and effect of this example will be described. In the thermoelectric generator 103 of this example, the spacer portion 223 of the emitter substrate 203 is in contact with the surface 41 of the collector substrate 403, and the spacer portion 423 of the collector substrate 403 is in contact with the surface 21 of the emitter substrate 203. As described above, the spacer portion 223 of the emitter substrate 203 and the spacer portion 423 of the collector substrate 403 are not necessarily arranged at positions facing each other. As shown in this example, if the tips of the spacer portions 223 and 423 are configured to come into contact with the surface 21 of the emitter substrate 203 and the surface 41 of the collector substrate 403, the same effects as those of the first embodiment can be obtained. be able to.

  In addition, the emitter substrate 203 in the thermoelectric generator 103 is made of a diamond semiconductor. Therefore, the emitter substrate 203 has a high thermal conductivity, and heat applied from an external heat source can be efficiently transmitted to the emitter 3. As a result, the thermoelectric power generation element 103 tends to have higher power generation efficiency.

  The emitter substrate 203 and the collector substrate 403 are made of diamond semiconductor having the specific crystal orientation. Then, the emitter reinforcing convex portion 233 and the collector reinforcing convex portion 433 are formed by aligning the crystal orientation so that the side surface 25 of the emitter reinforcing convex portion 233 and the side surface 45 of the collector reinforcing convex portion 433 have the specific crystal orientation. Yes. Therefore, as described above, the emitter 3 and the collector 5 can be formed at the specific position by selective epitaxial growth. In this case, processes such as patterning and etching for forming the emitter 3 and the collector 5 at specific positions can be omitted. As a result, the manufacturing process can be easily shortened, and the productivity of the thermoelectric generator 103 can be further improved.

  In this case, the growth direction of the emitter 3 and the collector 5 and the crystal orientation of the surfaces 31 and 51 can be easily controlled. Therefore, the parallelism between the surface 31 of the emitter 3 and the surface 51 of the collector 5 can be easily improved. As a result, the thermionic power generation element 103 tends to have higher power generation efficiency. In addition, the same effects as those of the first embodiment can be achieved.

(Modification 1)
In this example, as shown in FIG. 19, the connection portion 12 in the thermoelectric generator 1 of Example 1 is formed on the back surface of the emitter substrate 2 and the collector substrate 4. The emitter substrate 2 in the thermoelectric power generation element 104 of the present example has a plurality of through holes 29 formed so as to penetrate in the thickness direction (overlapping direction Z). The through hole 29 is formed in a region of the emitter substrate 2 where the emitter 3 is disposed.

  Similarly, the collector substrate 4 has a plurality of through holes 49 formed so as to penetrate in the thickness direction (the overlapping direction Z). The through hole 49 is formed in a region of the collector substrate 4 where the collector 5 is disposed.

  The connection portion 124 of this example is made of metal, is disposed so as to cover the back surfaces of the emitter substrate 2 and the collector substrate 4, and is filled in the through holes 29 and 49. Thereby, the connection part 124 is made to contact the back surface 33 of the emitter 3 and the back surface 53 of the collector 5, and the emitter 3 and the collector 5 can be connected to the load.

  As described above, by arranging the connection portion 124 on the back surface of the emitter substrate 2 and the collector substrate 4, the area of the connection portion 124 can be easily increased. Therefore, the thermoelectric generator 104 and the external circuit can be connected more easily, and the reliability can be improved more easily.

(Modification 2)
In this example, the arrangement of the emitter 3 and the collector 5 in the third embodiment is changed. Similarly to the first embodiment, the emitter 3 and the collector 5 may be configured to cover the surface 21 of the emitter substrate 2 and the surface 41 of the collector substrate 4 (see FIG. 20). Further, as shown in FIG. 21, the emitter 3 and the collector 5 may not be formed at a position facing the emitter reinforcing convex portion 233 or the collector reinforcing convex portion 433.

  In Examples 1 to 3 and Modifications 1 and 2, an example in which spacer portions and reinforcing convex portions are provided on both the emitter substrate and the collector substrate is shown. However, the spacer portions and reinforcing convex portions are formed on the emitter substrate. Alternatively, it may be provided on at least one of the collector substrates. That is, for example, a configuration in which a spacer portion or a reinforcing convex portion is provided only on the emitter substrate, or a configuration in which a spacer portion or a reinforcing convex portion is provided only on the collector substrate can be employed.

  In addition, although the example in which the emitter surface 31 and the collector surface 51 are configured to be parallel to each other is shown, the emitter surface 31 and the collector surface 51 may not be parallel.

  Further, materials other than the n-type diamond semiconductor can be used for the emitter 3 and the collector 5. As the material of the emitter 3 and the collector 5, for example, semiconductors such as Si, GaN, SiC, BN, GaAs, InP, various metals, and the like can be used. In the case of using a semiconductor, a donor or an acceptor may be added as appropriate so as to exhibit either n-type or p-type conductivity. The material of the emitter 3 and the collector 5 can be appropriately selected according to desired characteristics such as, for example, power generation efficiency, the magnitude of the thermoelectron current, or an output voltage.

DESCRIPTION OF SYMBOLS 1, 102, 103 Thermionic power generation element 2, 202, 203 Emitter substrate 21 Emitter substrate surface 22, 223 Spacer part 3 Emitter 31 Emitter surface 4, 402, 403 Collector substrate 41 Collector substrate surface 42, 423 Spacer part 5 Collector 51 Collector surface

Claims (9)

An emitter substrate (2, 202, 203) made of a high resistance material;
An emitter (3) formed on the surface of the emitter substrate (2, 202, 203) for generating thermionic electrons;
A collector substrate (4, 402, 403) made of a high resistance material disposed opposite to the emitter substrate (2, 202, 203);
A collector (5) formed on the surface of the collector substrate (4, 402, 403) and collecting the thermal electrons,
At least one of the emitter substrate (2, 202, 203) and the collector substrate (4, 402, 403) has a spacer portion (22, 223, 42, 423) protruding toward the other,
The tip of the spacer part (22, 223, 42, 423) is the spacer part (22, 223, 42, 403) of the emitter substrate (2, 202, 203) and the collector substrate (4, 402, 403). 423) is in contact with the substrate opposite to the protruding substrate, the thermoelectric generator (1, 102, 103, 104). Both the emitter substrate (2, 202) and the collector substrate (4, 402) have the spacer part (22, 42), and the spacer part (2, 202) provided on the emitter substrate (2, 202). 22. The thermoelectric generator (1, 2) according to claim 1, wherein a tip of the spacer part (42) provided on the collector substrate (4, 402) is in contact with each other. 102, 104). At least one of the emitter substrate (202, 203) and the collector substrate (402, 403) has a reinforcing projection (23, 233, 43, 433) protruding toward the other, and the emitter (3 ), Of the collector (5), the emitter substrate (2, 202, 203) and the collector substrate (4, 402, 403), the member facing the tip of the reinforcing projection (23, 233, 43, 433) A gap is formed between (2, 202, 203, 23, 233, 3, 4, 402, 403, 43, 433, 5) and the tip of the reinforcing protrusion (23, 233, 43, 433). In the state where the emitter substrate (2, 202, 203) or the collector substrate (4, 402, 403) is curved, the reinforcing projections (23, 233, 43, 433) Claims, characterized in that the tip, and a member (2,202,203,23,233,3,4,402,403,43,433,5) facing thereto is configured to be abutted The thermoelectric generator (102, 103, 104) according to 1 or 2 . The thermoelectric generator ( 1) according to any one of claims 1 to 3, characterized in that the surface (31) of the emitter (3) and the surface (51) of the collector (5) are parallel to each other. 1, 102, 103, 104). The thermoelectron generator (1, 102 ) according to claim 4 , characterized in that the surface (31) of the emitter (3) and the surface (51) of the collector (5) face each other through a gap. , 103, 104). The thermoelectric generator (1, 102, 103, 104) according to any one of claims 1 to 5 , wherein the emitter (3) is made of a semiconductor. The thermoelectric generator (1, 102, 103, 104) according to claim 6 , characterized in that the emitter (3) is made of a diamond semiconductor whose surface is hydrogen-terminated. The emitter (3) is made of a diamond semiconductor having either n-type or p-type conductivity, and the collector (5) has either n-type or p-type conductivity, and the emitter ( The thermionic power generation element (1, 102, 103, 104) according to claim 7, which is made of a diamond semiconductor having a dopant concentration lower than that of 3). The emitter substrate (203) and the collector substrate (403) made of a diamond semiconductor whose surface (41) in the thickness direction is a (001) plane;
It has a substantially rectangular parallelepiped shape in which the top surface (24) is the (001) surface and the side surface (25) is the {110} surface, which is erected from the emitter substrate (203) to the collector substrate (403). A plurality of emitter reinforcing protrusions (233);
The emitter (3) disposed on the base (26) of the emitter reinforcing projection (233) and having a surface (31) of a {111} plane;
It has a substantially rectangular parallelepiped shape in which the top surface (44) is the (001) surface and the side surface (45) is the {110} surface, which is erected from the collector substrate (403) to the emitter substrate (203). A plurality of collector reinforcing protrusions (433);
The collector (5) is disposed on the base (46) of the collector reinforcing protrusion (433), and the surface (51) is a {111} plane,
The top surface (25) of the emitter reinforcing projection (233) faces the collector substrate (403) through a gap, and the emitter substrate (203) or the collector substrate (403) is curved. It is configured to be able to contact the collector substrate (403),
The top surface (45) of the collector reinforcing projection (433) faces the emitter substrate (203) through a gap, and the emitter substrate (203) or the collector substrate (403) is curved. It is configured to be able to contact the emitter substrate (203),
The emitter reinforcing protrusions (233) and the collector reinforcing protrusions (433) are alternately arranged so that the side surfaces (25, 45) face each other,
The surface (31) of the emitter (3) and the surface (51) of the collector (5) are parallel to each other between the adjacent emitter reinforcing convex portion (233) and the collector reinforcing convex portion (433). The thermoelectric generator (103) according to claim 8 , wherein the thermoelectric generator (103) is provided.

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