SEMICONDUCTOR THERMOELECTRIC GENERATOR

Abstract

The invention relates to thermoelectric generators, and more particularly to thermoelectric generators functioning on the thermoelectric properties of graded-gap structures, i.e. the properties of graded-gap semiconductors with alternating dopants and of heterojunctions therebetween, as well as on the properties of intrinsic semiconductor materials, and can be used, inter alia, for powering domestic electric appliances and charging power-supply elements of portable electronic devices.

The present semiconductor thermoelectric generator comprises a semiconductor assembly configured to be capable of extracting heat from the surrounding environment, said semiconductor assembly containing at least one pair of interconnected graded-gap semiconductors, wherein a wide-gap side of at least one graded-gap semiconductor is connected to a narrow-gap side of at least one other graded-gap semiconductor. The junction between the graded-gap semiconductors is configured using an intrinsic semiconductor material and the graded-gap semiconductors are configured using alternating dopants, wherein the wide-gap sides of pairwise-connected graded-gap semiconductors are doped with an acceptor impurity.

The technical result of the claimed invention consists in improving the efficiency, power and output of a thermoelectric generator and expanding the functionality thereof.

Claims

1. The semiconductor thermoelectric generator, which includes the semiconductor assembly configured to extract heat from the surrounding environment, comprising at least one pair of interconnected graded-gap semiconductors, wherein, the wide-gap side of at least one graded-gap semiconductor is connected with the narrow-gap side of at least one another graded-gap semiconductor, wherein the junction between graded-gap semiconductors is configured using semiconductor intrinsic material, graded-gap semiconductors are configured using alternating dopants, while, the wide band-gap sides of the pairwise-connected graded-gap semiconductors are doped with an acceptor impurity.

2. The semiconductor thermoelectric generator according to claim 1, wherein the edge area of the narrow-gap side of one of the graded-gap semiconductors, located in the junction between graded-gap semiconductors, is made of semiconductor intrinsic material.

3. The semiconductor thermoelectric generator according to claim 1, wherein in the junction between graded-gap semiconductors there is an intermediate layer of semiconductor intrinsic material, through which they are connected.

4. The semiconductor thermoelectric generator according to claim 1, wherein the outer surfaces of the semiconductor assembly have ohmic contacts, and one terminal is connected to each outer surface of the semiconductor assembly.

5. The semiconductor thermoelectric generator according to claim 1, wherein on the semiconductor assembly outer surfaces with ohmic contacts there are contact elements configured to extract heat from a heat carrier, and one terminal is connected to each outer surface of the semiconductor assembly.

6. The semiconductor thermoelectric generator according to claim 1, wherein the semiconductor assembly includes a pair of graded-gap semiconductors, and each of them has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity and the narrow-gap side Ge.sub.j, which comprises intrinsic germanium, while, the narrow-gap side Gej of one graded-gap semiconductor is connected with the wide-gap side Si.sub.p of the other graded-gap semiconductor, but not with the interconnected sides of graded-gap semiconductors, which are the outer surfaces of the semiconductor assembly, terminals are connected and there are ohmic contacts on the said outer surfaces.

7. The semiconductor thermoelectric generator according to claim 1, wherein the semiconductor assembly includes a pair of graded-gap semiconductors, one of which has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity and the narrow-gap side Ge.sub.n, which comprises germanium with a donor impurity, the other graded-gap semiconductor has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity and the narrow-gap side Ge.sub.j, which comprises intrinsic germanium, between the narrow-gap side Ge.sub.n of one graded-gap semiconductor and the wide-gap side Si.sub.p of the other graded-gap semiconductor there is an intermediate layer of intrinsic germanium Ge.sub.i through which the graded-gap semiconductors are connected, but not to the sides of graded-gap semiconductors connected with the intermediate layer, which are the outer surfaces of the semiconductor assembly, terminals are connected and there are ohmic contacts on the said outer surfaces.

8. The semiconductor thermoelectric generator according to claim 1, wherein the semiconductor assembly includes a pair of graded-gap semiconductors, and each of them has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity and the narrow-gap side Ge.sub.n, which comprises germanium with a donor impurity, while, between the narrow-gap side Ge.sub.n of one graded-gap semiconductor and the wide-gap side Si.sub.p of the other graded-gap semiconductor there is an intermediate layer of intrinsic germanium Ge.sub.i through which the graded-gap semiconductors are connected, but not to the sides of graded-gap semiconductors connected with the intermediate layer, which are the outer surfaces of the semiconductor assembly, terminals are connected and there are ohmic contacts on the said outer surfaces.

Description

[0034] Design of the claimed semiconductor thermoelectric generator is clarified by the following figures.

[0035] FIG. 1—View of the claimed semiconductor thermoelectric generator in the embodiment where the semiconductor assembly includes a pair of graded-gap semiconductors, and each of them has the wide-gap side Sip, which comprises silicon doped with an acceptor impurity, and the narrow-gap side Ge.sub.i, which comprises intrinsic germanium, while, the narrow-gap side Gej of one graded-gap semiconductor is connected with the wide-gap side Si.sub.p of the other graded-gap semiconductor, but not with the interconnected sides of graded-gap semiconductors, which are the outer surfaces of the semiconductor assembly, terminals are connected and there are ohmic contacts on the said outer surfaces.

[0036] FIG. 2—View of the claimed semiconductor thermoelectric generator in the embodiment where the semiconductor assembly includes a pair of graded-gap semiconductors, one of which has the wide-gap side Sip, which comprises silicon doped with an acceptor impurity and the narrow-gap side Ge.sub.n, which comprises germanium with a donor impurity, the other graded-gap semiconductor has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity, and the narrow-gap side Ge.sub.i, which comprises intrinsic germanium, between the narrow-gap side Ge.sub.n of one graded-gap semiconductor and the wide-gap side Si.sub.p of the other graded-gap semiconductor there is an intermediate layer of intrinsic germanium Ge.sub.i through which the graded-gap semiconductors are connected, but not to the sides of graded-gap semiconductors connected with the intermediate layer, which are the outer surfaces of the semiconductor assembly, terminals are connected and there are ohmic contacts on the said outer surfaces.

[0037] FIG. 3—View of the claimed semiconductor thermoelectric generator in the embodiment where the semiconductor assembly includes a pair of graded-gap semiconductors, and each of them has the wide-gap side Sip, which comprises silicon doped with an acceptor impurity, and the narrow-gap side Ge.sub.n, which comprises germanium with a donor impurity, while, between the narrow-gap side Ge.sub.n of one graded-gap semiconductor and the wide-gap side Si.sub.p of the other graded-gap semiconductor there is an intermediate layer of intrinsic germanium Ge.sub.I through which the graded-gap semiconductors are connected, but not to the sides of graded-gap semiconductors connected with the intermediate layer, which are the outer surfaces of the semiconductor assembly, terminals are connected and there are ohmic contacts on the said outer surfaces.

[0038] The following conventions are used in Figures:

[0039] Si.sub.p— graded-gap semiconductor wide-gap side consisting of silicon doped with an acceptor impurity in the embodiment;

[0040] Gej—graded-gap semiconductor narrow-gap side consisting of intrinsic germanium in the embodiment;

[0041] Ge.sub.n— graded-gap semiconductor narrow-gap side consisting of germanium with donor impurity in the embodiment;

[0042] Gei—intermediate layer of intrinsic germanium

[0043] —heat carrier motion

[0044] — drift current

[0045] —diffusion current

[0046] —thermal current

[0047] —thermal generation current

[0048] —terminals.

[0049] The Figures illustrate schematic views of the preferred but not exclusive embodiments of the claimed semiconductor thermoelectric generator, which includes a semiconductor assembly 1 comprising a pair of interconnected graded-gap semiconductors 2, two ohmic contacts 3 and two terminals 4. Besides, the Figures illustrate schematically and in simplified form the directions of diffusion and drift current, thermal current and thermal generation current, and also structure and materials of the graded-gap semiconductors 2.

[0050] Thermoelectric generator or thermogenerator in this case means a device which converts thermal energy into electric current.

[0051] In the illustrated embodiments the semiconductor assembly 1 comprises a pair of interconnected graded-gap semiconductors 2 variably doped. In the preferable embodiment the graded-gap semiconductors 2 are integrally connected with each other or with the intermediate layer 6 by soldering, splicing or any other similar method forming a heterojunction in the junction point of the pairwise-connected graded-gap semiconductors 2. The wide-band sides of the pairwise-connected graded-gap conductors 2 are doped with acceptor impurity.

[0052] The junction point of the pairwise-connected graded-gap semiconductors 2 is configured using semiconductor intrinsic material. In the embodiment of the claimed semiconductor thermoelectric generator illustrated in FIG. 1 the edge area of the narrow-gap side of one of the graded-gap semiconductors 2, located in the junction point of the graded-gap semiconductors 2, is made of semiconductor intrinsic material. In the embodiments of the claimed semiconductor thermoelectric generator illustrated in FIGS. 2 and 3 in the point of graded-gap semiconductors junction there is an intermediate layer 6 of semiconductor intrinsic material, through which the graded-gap semiconductors 2 are connected. In all the above embodiments the semiconductor intrinsic material is germanium. However, such material could be any material which band-gap width is narrower than the band-gap width of the wide-band sides of the graded-gap semiconductors 2.

[0053] In the preferred embodiment illustrated in FIG. 1, each of the graded-gap semiconductors 2 consists of the wide-gap side Sip, which comprises silicon doped with an acceptor impurity, the narrow-gap side Ge.sub.i, which comprises intrinsic germanium, and intermediate area between them with blend chemical composition, where germanium content is gradually decreased and silicon content is gradually increased in the direction to the wide-gap side.

[0054] In the preferred embodiment illustrated in FIG. 2, one of the graded-gap semiconductors 2 has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity, and the narrow-gap side Ge.sub.n, which comprises germanium with a donor impurity, the other graded-gap semiconductor 2 has the wide-gap side Sip, which comprises silicon doped with an acceptor impurity, and the narrow-gap side Gei, and between the narrow-gap side Ge.sub.n of one graded-gap semiconductor 2 and the wide-gap side Sip of the other graded-gap semiconductor 2 there is the intermediate layer 6 of intrinsic germanium Ge.sub.i, through which the graded-gap semiconductors 2 are connected.

[0055] In the preferred embodiment illustrated in FIG. 3, each of the graded-gap semiconductors 2 has the wide-gap side Si.sub.p, which comprises silicon doped with an acceptor impurity, and the narrow-gap side Ge.sub.n, which comprises germanium with a donor impurity, while between the narrow-gap side Ge.sub.n of one graded-gap semiconductor 2 and the wide-gap side Si.sub.p of the other graded-gap semiconductor 2 there is the intermediate layer 6 of intrinsic germanium Ge.sub.i, through which the graded-gap semiconductors 2 are connected.

[0056] However, the graded-gap semiconductors 2 could be made of any semiconductor materials which have different band-gap width and could be combined in a graded-gap semiconductor taking the above conditions into account. Also, in the preferred embodiment the acceptor impurity for the wide band-gap sides of the graded-gap semiconductors 2 is trivalent boron, and the donor impurity for the narrow band-gap sides of the graded-gap semiconductors 2 in the corresponding embodiments is quinquivalent phosphorus. However, other similar materials in accordance with semiconductor materials, which compose the graded-gap semiconductors 2, could be used as acceptor and donor impurities.

[0057] In the illustrated embodiments of the claimed invention the graded-gap semiconductors 2 are in the form of plates and connected in the horizontal plane. The graded-gap semiconductors 2 can be produced by liquid phase epitaxy method, gaseous-phase ion-beam epitaxy method, diffusion method or by germanium or silicon sputtering on aluminum or nickel substrate. However, other materials, which correspond to the properties of graded-gap semiconductor materials, could be used as a substrate.

[0058] There are two ohmic contacts 3 on the outer surfaces of the semiconductor assembly 1, which are the outer surfaces of the graded-gap semiconductors 2. In the illustrated embodiment the ohmic contacts 3 are horizontally-oriented plates integrally connected with the outer surfaces of the semiconductor assembly 1, which are made of aluminum in the preferred embodiment of the claimed invention. However, the ohmic contacts 3 could be made of other material with high thermal conductivity, chemical resistance and resistance to high temperature.

[0059] Two terminals 4 are connected to the narrow-gap side of one graded-gap semiconductor 2 and to the wide-gap side of the other graded-gap semiconductor 2, which outer surfaces are the outer surfaces of the semiconductor assembly 1. In the preferred embodiment the terminals 4 are connected to the said surfaces of the graded-gap semiconductors 2 and to the ohmic contacts 3 and are coated with insulation. Material of the terminals 4 metal contacts could be, for example, copper or other chemical elements with apparent metallic properties.

[0060] In the illustrated embodiment the claimed semiconductor thermoelectric generator is located between two means for heat carrier 5 transfer, through which fluid or gaseous heat carrier passes. Such means for heat carrier transfer could be, for example, solar collector coil pipes, components of heating devices or other similar means.

[0061] The claimed semiconductor thermoelectric generator is used as follows.

[0062] The terminal 4 contacts are connected, for example, to a current-to-voltage converter, forming an electrical circuit and locate the claimed semiconductor thermoelectric generator between the heat carrier 5 transfer means so that the ohmic contacts 3 are in direct contact with the surfaces of the heat carrier 5 transfer means or with the contact elements configured to extract heat from the heat carrier in the corresponding embodiment of the claimed thermoelectric generator. After that, the heat carrier being in the said transfer means 5 is heated by an external heat source, for example, by means of fuel, gas or accumulated sun beams.

[0063] Thermal energy from the heat carrier passes through the ohmic contacts 3, through the outer surfaces of the semiconductor assembly 1 and heats the graded-gap semiconductors 2 uniformly, that starts operation of the claimed thermoelectric generator. Due to charge carriers motion between the sides of the graded-gap semiconductors 2 diffusion current, drift current, thermal current and thermal generation current occur through the heterojunction between the graded-gap semiconductors 2, while the directions of diffusion current, thermal current and thermal generation current are the same.

[0064] Thus, electric current occurs in the formed electrical circuit and is transferred through the terminals 4, for example, to the current-to-voltage converter or converters and could be used for powering domestic electric appliances, technical equipment, charging the batteries of portable electronic devices, etc.

[0065] At the same time, heating of the heat carrier 5 does not require considerable energy consumption and sophisticated equipment, and its rate is easily controlled by a user of the claimed semiconductor thermoelectric generator. In order to stop the claimed thermoelectric generator it is sufficient to disconnect wires of the terminals 4 from the device closing the electrical circuit or stop heating the heat carrier 5 or to remove the claimed semiconductor thermoelectric generator from the space between the heat carrier 5 transfer means.

[0066] At the same time, it is necessary to take into consideration that each of the above three preferred embodiments of the claimed semiconductor thermoelectric generator has optimal output at specific heat carrier temperature. Thus, the embodiment of the claimed semiconductor thermoelectric generator illustrated in FIG. 1 is used, if the heat carrier temperature equals or exceeds the temperature at which the narrow-gap side electrons of the graded-gap semiconductors 2 acquire energy required to convert into the charge carriers. The embodiment of the claimed semiconductor thermoelectric generator illustrated in FIG. 2 is used, if the heat carrier temperature equals or is below the temperature at which the narrow-gap side electrons of the graded-gap semiconductors 2 acquire energy required to convert into the charge carriers. The embodiment of the claimed semiconductor thermoelectric generator illustrated in FIG. 3 is used, if the heat carrier temperature is substantially below the temperature at which the narrow-gap side electrons of the graded-gap semiconductors 2 acquire energy required to convert into the charge carriers.

[0067] Also, in order to increase power of the generated current, several claimed thermoelectric generators could be connected in parallel through the metal contacts located between the outer surfaces of the semiconductor assemblies 1.

[0068] The existing sources of patent and scientific and technical information do not disclose a semiconductor thermoelectric generator which has the claimed set of essential features. therefore, the proposed technical solution complies with the novelty patentability criterion.

[0069] Comparative analysis of the above technical solution and the closest prior art has demonstrated that implementation of the set of essential features characterizing the proposed invention results in qualitatively new technical properties stated above, which combination has not been established before in the prior art, that enables to make a conclusion about compliance of the proposed technical solution with the inventive level patentability criterion.

[0070] The proposed technical solution is industrially applicable, since it does not comprise any structural elements and materials which cannot be reproduced at the modern technology development stage in industrial production surrounding environment.