RU2120684C1 - Semiconductor part and thermoelectric device - Google Patents

Abstract

FIELD: semiconductor engineering; thermoelectric devices depending for their operation on Peltier and Seebeck effects. SUBSTANCE: semiconductor part made of layer-structure crystalline material of type AV, BV1 with junction planes between layers is made in the form of polyhedron that has first pair of parallel faces and second pair of parallel faces which is in essence perpendicular to junction surfaces. The latter are inclined to parallel faces of first pair through maximum 7 deg. Parallel faces of first pair are formed by surfaces of crystalline material obtained as result of its crystallization and are not subjected to subsequent destruction treatment; parallel faces of second pair are produced by destruction treatment. Thermoelectric device incorporating at least one p-type semiconductor part made of first layer-structure crystalline material and at least one n-type layer-structure semiconductor part has each semiconductor part made in the form of bar whose first surface is connected to electrode and second and third surfaces are perpendicular to first surface. All layers of crystalline material used for manufacturing each semiconductor part are inclined through maximum 7 deg. to mentioned second and third surfaces. EFFECT: provision for maintaining electrical and thermal properties of device in case of cracking of any semiconductor part causing only negligible reduction in its strength. 4 cl, 9 dwg

Description

1. The technical field
The invention relates to semiconductor technology and, more specifically, to semiconductor products from crystalline materials with a specific structure and to thermoelectric devices with such semiconductor products and can be used in thermoelectric devices based on Peltier and Seebeck effects.

 2. The prior art.

 When creating thermoelectric devices based on the Peltier and Seebeck effects - thermoelectric generators, cooling and heating devices - there is a problem of providing both good transforming properties and their sufficient mechanical strength.

Known semiconductor products with p-type and n-type conductivity used in known thermoelectric devices made of crystalline materials of type A _V B _VI with a layered structure having cleavage planes between layers and made in the form of a polyhedron having at least one pair of parallel faces, have a significant difference in strength, electrophysical and thermophysical properties in different directions relative to cleavage planes (see AD Belava, SA Zavakin, VS Zemskov "Mechanical properties of Bi-Sb singe crystals solid solutions gr own by Czachralski metod ", XIV International Conference on Thermoelectrics Trancsactions, June 27-30, 1995, St. Petersburg, Russia, p. 37 - 41).

 Known semiconductor products have low strength and can crack along the cleavage planes of crystalline material under the action of power and thermal loads, which causes problems both in the manufacture of thermoelectric devices with such products and in the operation of such thermoelectric devices.

 Also known are thermoelectric devices comprising at least one p-type semiconductor product made of a first crystalline material with a layered structure, at least one n-type semiconductor product made of a second crystalline material with a layered structure, and at least one electrode connected to both p-type and n-type semiconductor products (see the book "Thermoelectric Coolers" edited by A. L. Weiner, Moscow, ed. "Radio and Communication", 1983, p. 21, Fig. 1.8) .

 Such devices based on well-known semiconductor products due to the low strength of the latter do not have the optimal combination of strength, electrophysical and thermophysical properties.

3. Disclosure of invention
The present invention is the creation of semiconductor products, mainly for thermoelectric devices, and thermoelectric devices, and thermoelectric devices based on such semiconductor products having an optimal combination of strength, electrophysical and thermophysical properties.

This problem is solved in that in a semiconductor product, mainly for thermoelectric devices made of a crystalline material of type A _V B _VI with a layered structure, having cleavage planes between the layers, and made in the form of a polyhedron having at least one pair of parallel faces, according to the invention, all the cleavage planes of the layers of crystalline material from which the product is made, are located relative to these parallel faces at angles of not more than 7 ^o .

 With this embodiment of the semiconductor product in the event of cracking along the cleavage plane of the single crystal layers or the cleavage planes of the layers of blocks of single crystals from which it is formed, its electrophysical and thermophysical properties are preserved and the strength of the device in which such a semiconductor product is slightly reduced due to the fact that it retains the ability to transmit mechanical forces.

 It is advisable that these parallel faces of the semiconductor product were formed by the surfaces of the crystalline material obtained as a result of its crystallization and free from subsequent destructive processing. This embodiment of the semiconductor product further improves its strength, as well as electrophysical and thermophysical properties.

 In one embodiment of the semiconductor product, each face of the specified pair of parallel faces can be made in the form of a rectangle. In this case, the size of one of the sides of the specified rectangle can be at least an order of magnitude larger than the size of the second of the sides of the specified rectangle, perpendicular to the first side.

 In another embodiment of the semiconductor product, each face of the specified pair of parallel faces can be made in the form of a trapezoid.

 The semiconductor product can be made with a second pair of faces located essentially perpendicular to the specified cleavage planes of the layers of crystalline material. In this case, the faces of the second pair can be formed by the surfaces of the crystalline material obtained by destructive processing, for example, by cutting. In addition, at least a portion of the surface of at least one of the faces of the second specified pair may be coated with at least one electrically conductive layer.

The problem with the thermoelectric device as a whole is solved by the fact that in the thermoelectric device containing at least one p-type semiconductor product made of a first crystalline material with a layered structure, at least one n-type semiconductor product made of a second crystalline material with a layered structure, and at least one electrode connected to both p-type and n-type semiconductor products, according to the invention, all layers of crystalline m materials from which semiconductor products are made are mutually located at angles of not more than 7 ^o .

 With this embodiment of the thermoelectric device, in the case of cracking of any semiconductor product along the boundaries of the layers of the material from which this product is made, the electrophysical and thermophysical properties of the device are preserved and its strength is slightly reduced due to the fact that parts of the semiconductor product retain the ability to transmit mechanical forces.

It is advisable that in such a thermoelectric device each p-type and n-type semiconductor product is made in the form of a bar having a first surface connected to the electrode, a second and third opposite surfaces located perpendicular to the first specified surface and having each shape of a rectangle with a ratio of length in pairs of opposite sides, differing by at least an order of magnitude, and all layers of the crystalline material from which each semiconductor product is made were located us about its second and third of said opposing surfaces at angles of not more than 7 ^o.

 The aforementioned semiconductor product and thermoelectric device are interconnected by a single inventive concept, ensuring the optimal combination of strength, electrophysical and thermophysical properties of the semiconductor product and the thermoelectric device as a whole.

 4. A brief description of the drawings.

 The accompanying drawings show: in FIG. 1 - semiconductor product - General view, the first option; in FIG. 2 is a view along arrow A in FIG. one; in FIG. 3 is a section B-B in FIG. 2; in FIG. 4 is a section C-C in FIG. 2 on an enlarged scale; in FIG. 5 - semiconductor product - General view, the second option; in FIG. 6 is a view along arrow D in FIG. 5; in FIG. 7 - thermoelectric device, side view; in FIG. 8 is a section E-E in FIG. 7; in FIG. 9 is a sectional view F-F in FIG. 7.

5. Embodiments of the Inventions
In FIG. 1 to 4 show a first embodiment of a semiconductor product according to the invention. As shown in FIG. 1, the semiconductor product 1 has the shape of a polyhedron with a pair of parallel faces 2, 3. The semiconductor product 1 is made of a crystalline material of type A _V B _VI , for example, a Bi - Te solid solution having a composition with or without alloying impurities, providing conductivity p -type or n-type. The semiconductor product 1 is a processed single crystal or block crystal. The crystalline material of which the semiconductor product 1 is made has a layered structure with cleavage planes 4 ¹ -4 ^IV (Fig. 3 and 4) both between the layers inside each single crystal or block, and between the crystalline blocks (fig. 3 and 4 conventionally only a few cleavage planes 4 ¹ - 4 ^IV of those available in crystalline material are shown and indicated). Parallel faces 2, 3 (Figs. 1 to 4) are formed by the surfaces of the crystalline material obtained as a result of its crystallization and free from subsequent destructive processing, for example, by cutting or other destruction of the surface layer. All cleavage planes 4 ¹ - 4 ^IV layers of the crystalline material from which the semiconductor product 1 is made, are located relative to parallel faces 2, 3 at angles α, β of no more than 7 ^o . Each face 2, 3 (Fig. 2) of the semiconductor product 1 is made in the form of a rectangle. The size a of the first side (not labeled) of this rectangle is at least an order of magnitude (i.e., ten or more times) larger than the size b of the second side (not labeled) of this rectangle, which is perpendicular to the first side.

Wafer 1 (Figure 1 -. 4) formed with a second pair of faces 5, 6 arranged substantially perpendicular to the cleavage planes 4 ¹ - 4 ^IV crystal material layers (Figure 4.). Facets 5, 6 (Figs. 1-4) are formed by surfaces of crystalline material obtained by destructive treatment, for example, by cutting. A part of the surface or the entire surface of one of the faces 5, 6 or both faces 5, 6 may be coated with one conductive layer 7 and / or 8 or several conductive layers (not shown and not indicated).

 In FIG. 5 to 6 show a second embodiment of a semiconductor product according to the invention. As shown in FIG. 5, the semiconductor article 1 ′ made of the same material as the semiconductor article 1 shown in FIG. 1 - 4, has the shape of a polyhedron with a pair of parallel faces 2 '- 3', and a second pair of faces 5 '- 6', located in the same way as faces 5 - 6 of the semiconductor product 1. Each face 2 '- 3' is made in the form trapezoid. In the semiconductor product 1 ', the location of the cleavage planes between the layers of crystalline material (not shown and not indicated in FIGS. 5 and 6) relative to faces 2', 3 'and the location of the faces 5' - 6 'relative to the cleavage planes is the same as in the semiconductor product 1 shown in FIG. 1 - 4. A part of the surface or the entire surface of one of the faces 5 ', 6' or both faces 5 '- 6' can also be coated with an electrically conductive layer 7 ', 8' or several electrically conductive layers.

In the manufacture of the described semiconductor products after crystallization of a material of type A _V B _VI , which is a Bi-Te solid solution with or without alloying impurities, or another material of the same type, a plate is obtained having two parallel surfaces located at a given distance from one another, relative to which the cleavage planes of the crystalline material are located at angles of not more than 7 ^o . The resulting plate is cut perpendicular to the cleavage planes of the crystalline material into blanks and then blanks are cut into products having the described polyhedron shape, leaving two parallel faces of each product unprocessed. In the process of processing the obtained plates before the final cutting of the workpieces or after cutting the workpieces into products having the indicated shape, the surfaces of the workpieces or products obtained as a result of destructive processing (cutting) can be coated with electrically conductive layers made of appropriate materials.

 The resulting semiconductor product due to the described arrangement of the cleavage planes of the layers of crystalline material has increased strength and, even in the case of cracking along the cleavage planes, retains the ability to transmit mechanical forces.

 In FIG. 7 to 9 show a thermoelectric device according to the invention.

 The thermoelectric device comprises a p-type semiconductor product 10, an n-type semiconductor product 11, and an electrode 12 connected to both semiconductor products 10, 11.

 The thermoelectric device may contain several semiconductor products 10, 11 and electrodes 12 (not shown in the drawings), i.e. can form a battery of thermocouples.

The semiconductor product 10 is made of a first crystalline material with a layered structure. The semiconductor product 11 is made of a second crystalline material with a layered structure. All layers 13 ¹ - 13 ^IV , 14 ¹ - 14 ^IV (Fig. 9) of the crystalline materials of which the products 10, 11 are made, are mutually arranged at angles of no more than 7 ^o (fig. 8 and 9 are conventionally shown and marked only a few layers 13 ¹ - 13 ^IV , 14 ¹ - 14 ^IV of those available in crystalline materials from which semiconductor products 10, 11 are made).

 The semiconductor product 10 (Fig. 8 - 9) is made in the form of a bar having a first surface 15 connected to the electrode 12, a second and third opposite surfaces 16, 17 located perpendicular to the surface 15. The semiconductor product 11 is also made in the form of a bar having a first the surface 18 connected to the electrode 12, the second and third opposite surfaces 19, 20 located perpendicular to the surface 18. Each of the surfaces 16, 17 and 19, 20 has a rectangular shape with a ratio of lengths c and d of pairwise opposite sides ( not indicated), which differ by at least an order of magnitude, i.e. ten or more times (Fig. 7). The semiconductor product 10 also has a fourth surface 21, the opposite surface 15, and the semiconductor product 11 has a fourth surface 22, the opposite surface 18 (Fig. 8).

All layers of crystalline material from which each semiconductor product 10, 11 is made, are located relative to surfaces 16, 17 and 19, 20, respectively, at angles of not more than 7 ^o (Fig. 9).

 The thermoelectric device can be included in the electrical circuit through electrodes (not shown and not shown in the drawings) connected to the surfaces 21, 22 of the semiconductor products 10, 11.

 The described thermoelectric device operates as follows.

 When a current is passed through a thermoelectric device as a result of the Peltier effect, a temperature difference arises between opposite surfaces of 15–21 and 18–22 of semiconductor products 10, 11, respectively. Depending on the direction of the current, one of the indicated surfaces of each semiconductor product is heated and the other is cooled, and thermoelectric device works simultaneously as a heating and cooling device. When external heating of one of the indicated opposite surfaces and cooling of the other of the indicated opposite surfaces 15 - 21 and 18 - 22 of the semiconductor products 10, 11 in the latter, an electric voltage arises as a result of the Seebeck effect, and the device operates as a thermoelectric generator. Due to the increased mechanical strength of the described thermoelectric device, its operation under severe conditions under the influence of mechanical and thermal loads is improved and, thereby, an optimal combination of strength, electrophysical and thermophysical properties is ensured.

6. Industrial applicability
The invention can be applied in thermoelectric generators, cooling and heating devices, as well as in measuring and other devices.

Claims (4)

1. A thermoelectric device comprising at least one p-type semiconductor product made of a first crystalline material with a layered structure, at least one n-type semiconductor product made of a second crystalline material with a layered structure, and at least one an electrode connected to both p-type and p-type semiconductor products, wherein each semiconductor product is made in the form of a bar having a first surface connected to the electrode, a second and a third o opposite surfaces located perpendicular to the first specified surface, characterized in that all layers of crystalline material from which each semiconductor product is made, are located relative to its second and third specified surfaces at an angle of not more than 7 ^o . 2. A semiconductor product for a thermoelectric device made of a crystalline material such as Av Bvi with a layered structure having cleavage planes between the layers and made in the form of a polyhedron having a first pair of parallel faces, a second pair of parallel faces, located essentially perpendicular to these surfaces cleavage, characterized in that all of these cleavage planes are located relative to the parallel faces of the first specified pair at angles of not more than 7 ^o .  3. The product according to claim 2, characterized in that the parallel faces of the first specified pair are formed by the surfaces of the crystalline material obtained as a result of its crystallization and free from subsequent destructive processing, and the parallel faces of the second specified pair are obtained by destructive processing, for example, by cutting.  4. The product according to p. 2, characterized in that at least part of the surface of at least one of the faces of the second specified pair is covered with at least one electrically conductive layer.

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