Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
  • H10N10/01—Manufacture or treatment
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
  • H10N10/80—Constructional details
  • H10N10/85—Thermoelectric active materials
  • H10N10/857—Thermoelectric active materials comprising compositions changing continuously or discontinuously inside the material

Definitions

• thermoelectric component and thermoelectric component
• the invention relates to methods for producing a thermoelectric component and to a thermoelectric component.
• thermoelectric components which generate an electrical voltage under the action of a temperature gradient are known from the prior art.
• US Pat. No. 6,300,150 describes a thermoelectric component which has a layer structure.
• thermoelectric device The problem underlying the invention is to provide a method with which an efficient thermoelectric device can be produced in the simplest possible way. Furthermore, a most efficient and yet easy to manufacture thermoelectric device should be provided.
• thermoelectric device includes a method for manufacturing a thermoelectric device, comprising the steps
• the first layers are arranged alternately with the second layers, wherein
• the generating of the first layers and / or of the second layers in each case comprises the production of at least one first output layer (precursor layer) and at least one second output layer.
• the first and second thermoelectric layers may be arranged and formed to form a superlattice.
• Such superlattices are characterized by a e.g. relatively high electrical but low thermal conductivity compared to non-layered materials.
• the relatively low thermal conductivity of such superlattices of thermoelectric layers can increase the thermoelectric efficiency of the thermoelectric device.
• the thermoelectric component has a superlattice with a total thickness of at least 5 ⁇ m, e.g. at least 18 ⁇ , in particular several 10 ⁇ , on.
• the thicknesses of the first and second thermoelectric layers are each in the range of a few nm (for example, at least about 10 nm), for example.
• the starting layers each have a thickness of at least a few atomic layers, e.g. in the range between 1 nm and 10 nm, for example at least 3 nm, at least 5 nm or at least 10 nm.
• thermoelectric material is a material that has a high compared to other materials thermoelectric coefficients, that can produce a relatively high temperature difference based on a voltage applied to the material or vice versa a relatively high voltage (
• a thermoelectric material may have a thermoelectric coefficient (Seebeck- coefficients) of more than 50 ⁇ / ⁇ . Examples of such thermoelectric materials are discussed below.
• the first and the second thermoelectric layer are produced in particular in such a way that in each case an intermediate layer is created between them, which has the first and the second thermoelectric material.
• Such an intermediate layer is formed, for example, when the first and second thermoelectric layers are formed by annealing (i.e., by heat treatment) the first and second starting layers.
• the phase boundaries between the first and second thermoelectric layers are not stepped. Rather, the intermediate layer forms a transition region in which the concentration of the first thermoelectric material drops substantially continuously from a first to an adjacent second layer or from the second thermoelectric material to an adjacent first layer. There are thus soft transitions between the first and second layers, which is why we can also speak of a "soft" superlattice.
• thermoelectric superlattice the diffusion between adjacent thermoelectric layers is thus not suppressed, but accepted as this simplifies the production of a thermoelectric superlattice and yet leads to a superlattice structure having a lower thermal conductivity than a homogeneous mixture of both layers and thus a high figure of merit (usually referred to as "Z", where Z takes into account the thermal conductivity, Seebeck coefficient and electrical conductivity).
• the materials of the first and second output layers combine to form the desired (first and second) thermoelectric layers.
• the stoichiometry of the first and the second layers can be adjusted, for example, via the thicknesses of the respective starting layers.
• the starting layers are exposed to a temperature which is higher than the temperature during the production of the starting layers; for example, a temperature between 100 ° to 500 ° C.
• a temperature which is higher than the temperature during the production of the starting layers; for example, a temperature between 100 ° to 500 ° C.
• the material of the first starting layer is an element of the sixth main group of the periodic table and the material of the second starting layer is an element of the fifth main group of the periodic table.
• bismuth or tellurium is used as the material for the starting layers, wherein - for example after an annealing step - thermoelectric layers of bismuth telluride are formed.
• thermoelectric layers a first starting layer of antimony or of antimony and bismuth and a second starting layer of telluride may be chosen, for example, to produce second thermoelective layers of antimony telluride (or antimony bismuth telluride) after annealing.
• thermoelectric material is not limited to a structure or a manufacturing method having only two different thermoelectric materials. It is also possible to provide more than two layers of different thermoelectric material.
• the first and second output layers are generated, for example, by sputtering.
• the sputtering takes place in such a way that the substrate on which the first and the second starting layers are deposited is moved alternately through the deposition region of a first sputtering target and the deposition region of a second sputtering target.
• the "deposition area” is a space area in which deposition of the material sputtered by a sputtering target onto the substrate is possible.
• the first sputtering target comprises the material of the first starting layer and the second sputtering target comprises the material of the second starting layer.
• targets are bimuth, tellurium, antimony or selenium targets (arranged stationary in a sputtering system).
• the substrate in the sputtering chamber
• the substrate is rotated in such a way that it alternately moves through the deposition region of a first sputtering target and the deposition region of a second sputtering target.
• the thickness of the output layers can be adjusted via the rotational speed of the substrate and / or the sputtering rate.
• the invention is of course not limited to the production of the parent layers by sputtering, but other deposition methods may also be used, e.g. Vapor deposition or MBE (molecular beam epitaxy).
• a tempering of the starting layers take place. This tempering is carried out in particular in a separate tempering.
• thermoelectric component in another aspect, relates to a method for producing a thermoelectric component, in particular according to one of the preceding claims, with the steps
• thermoelectric material - generating a plurality of first layers of a first thermoelectric material
• the first layers are arranged alternately with the second layers, and
• An intermediate layer between the first and the second layers is formed, comprising the first and the second material, wherein
• the first and / or the second thermoelectric material is a compound of at least one element of the fifth with at least one element of the sixth main group of the Periodic Table or a compound of at least one element of the fourth with at least one element of the sixth main group of the Periodic Table.
• output layers are not necessarily used to form the first and second thermoelectric layers. Rather, the thermoelectric layers can also be generated directly.
• the first and the second thermoelectric layers are produced by sputtering, with mixed targets in particular being used (see below).
• thermoelectric layer it is possible for the first and the second thermoelectric layer to be produced on a substrate by alternately passing the substrate through the deposition layer. rich of a first sputtering target and the deposition range of a second sputtering target moved (eg rotated), as already explained above for the first aspect of the invention.
• the first and second sputtering targets are each a mixed target, e.g. the first sputtering target comprises a first connection of at least one element of the fifth with at least one element of the sixth main group of the periodic table, and the second sputtering target comprises a second such connection, which is different from the first connection.
• the first compound is bismuth telluride and the second compound is antimony telluride.
• the targets are optimized (e.g., composition) so that, in combination with the sputtering conditions used (substrate temperature, sputtering rate, etc.), a layer having the desired properties (e.g., composition) can be produced.
• first and the second thermoelectric material are identical, for example, each consist of bismuth telluride.
• a barrier layer (X) between adjacent thermoelectric layers may be provided, for example, Ni, Cr, NiCr, Ti, Pt, TiPt, so that a layer sequence Bi 2 Te 3 -X-Bi 2 Te 3 would be generated.
• Bi 2 Te 3 - X - (Bi, Sb) 2 (Te, Se) 3 would also be conceivable.
• the first and the second thermoelectric layers are produced, for example, at a temperature between 20 ° and 300 ° C.
• first and the second thermoelectric layers can be subjected to an annealing step after they have been produced, in which case they are heated in particular to ⁇ ' ⁇ , for example to at least 100 ° C, at least 200 ° C or at least 300 ° C.
• the first thermoelectric material is silicon and the thermoelectric second material is germanium, wherein, for example, after production of the layers, an annealing step also takes place, for example with a temperature of at least 500 ⁇ €
• the invention also includes a thermoelectric device, with
• thermoelectric material a plurality of first layers of a first thermoelectric material
• thermoelectric material A plurality of second layers of a second thermoelectric material, wherein the first layers are arranged alternately with the second layers.
• thermoelectric component according to the invention thus has a periodic layer structure with at least two different thermoelectric materials.
• the formed between the thermoelectrically active layers intermediate layer (transition layer) is formed z.
• diffusion layer By diffusion of the first thermoelectric material to an adjacent (second) layer and vice versa of the second material to an adjacent (first) layer.
• the thickness of the intermediate layer is, as mentioned, for example at least 3 nm or at least 5 nm.
• the concentration of the first and the second thermoelectric material will vary depending on the location in the intermediate layer, wherein the limits of the intermediate layer (after which the thickness is measured) are in particular those Places between the first and the second layer are considered, at which the concentrations of the first and the second thermoelectric material decreases below one quarter of the corresponding concentration in the first and in the second layer.
• the first and / or the second thermoelectric material is a compound of at least one element of the fifth with at least one element of the sixth main group of the periodic table.
• the first thermoelectric material may be bismuth telluride or bismuth selenide
• the second thermoelectric material may be antimony telluride or antimony selenide.
• the formulation according to which the intermediate layer "comprises the first and second thermoelectric materials” naturally also covers the case that the first and second thermoelectric materials are present in the intermediate layer as (eg, ternary or quaternary) mixed compound.
• the thermoelectric layers may be formed of bismuth telluride and antimony telluride, respectively, and the intermediate layer of bismuth antimony telluride.
• the first and / or the second material is a compound of at least one element of the fourth with at least one element of the sixth main group of the periodic table, for. B. lead telluride or lead selenide.
• the first material is silicon and the second material is germanium.
• FIG. 1A shows a substrate 1 on which a plurality of output layers 2 to 4 are arranged periodically.
• the output layers serve to generate a thermoelectric superlattice.
• first output layers 2 as well as second output layers 3 adjoining these are provided, which are provided for forming first layers of a first thermoelectric material.
• the first starting layers 2 are made of tellurium and the second starting layers 3 are made of antimony. It is understood that other materials for these starting layers in question, for. For example, selenium instead of tellurium.
• first output layers 2 simultaneously serve to form second thermoelectric layers, since they each adjoin another (second) output layer 4 with their side facing away from the adjacent second output layer 3.
• the starting layer 4 is formed in the present example of bismuth.
• the layer structure shown in Figure 1 A After producing the layer structure shown in Figure 1 A, the z. B. by vapor deposition or sputtering, the layer structure is subjected to one or more Temper suitsen. This results - starting at the interfaces between the starting layers - a connection 20, 30 of the material (element) of the first output layers 2 with the material of the second output layers 3 and 4. The emergence of the compound is made by the interfaces of adjacent starting layers in the off Incidentally, as the material (s) of the starting layers diffuses through already formed compounds. This happens until the elementary materials of the starting layers have reacted and thus the first and second thermoelectric layers are produced. This process is shown in FIG. 1B.
• first thermoelectric layers of antimony telluride and second layers of bismuth telluride are formed.
• the ratio of the layer thicknesses of the second starting layers 3 and 4 to the thickness of the first starting layer 2, ie the ratio of the thickness of the antimony or bismuth layers to the thickness of the tellurium layers, determines the stoichiometry of the first and second thermoelectric material layers to be formed.
• the layer thicknesses are selected so that the first thermoelectric layers of Sb 2 Te 3 and the second thermoelectric layers of Bi 2 Te 3 are formed.
• thermoelectric material 20 see 20 (Sb 2 Te 3 ) and a plurality of second layers of a second thermoelectric material 30 (Bi 2 Te 3 ) which are arranged alternately; Compare FIG. 1C. Since an opposite diffusion of the elements of the second starting layers 3, 4 (antimony or bismuth) also occurs during the tempering process (FIG. 1B), intermediate layers 50 are formed between the first and second thermoelectric layers of the materials 20, 30 which have (Bi, Sb) 2 Te 3 , ie both Sb 2 Te 3 and Bi 2 Te 3 .
• both the first and second thermoelectric layers and simultaneously the intermediate layers are thus produced by the annealing.
• the layer structure shown in FIG. 1C thus has no abrupt phase transitions between the first thermoelectric layers and the second thermoelectric layers, but instead a (soft) transition zone in which the proportion of the first material 20 from a first layer to an adjacent second layer Layer and the proportion of the second material 30 decreases steadily from a second layer to an adjacent first layer.
• the method in particular the formation of the intermediate layers between the first and the second thermoelectric layers, can also be carried out with other starting layers, for. B. with selenium layers instead of the tellurium layers.

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• Physical Vapour Deposition (AREA)
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• Powder Metallurgy (AREA)

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• 2009
  • 2009-09-30 DE DE102009045208A patent/DE102009045208A1/de not_active Withdrawn
• 2010
  • 2010-09-29 EP EP10771687A patent/EP2483940A2/de not_active Withdrawn
  • 2010-09-29 WO PCT/EP2010/064433 patent/WO2011039240A2/de not_active Ceased
  • 2010-09-29 JP JP2012531403A patent/JP2013506981A/ja active Pending
  • 2010-09-29 US US13/498,863 patent/US20130068274A1/en not_active Abandoned

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