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
  • H10N10/80—Constructional details
• • 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
  • H10N10/851—Thermoelectric active materials comprising inorganic compositions
  • H10N10/852—Thermoelectric active materials comprising inorganic compositions comprising tellurium, selenium or sulfur
• • 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
  • H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
  • H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device
• • 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
  • H10N10/851—Thermoelectric active materials comprising inorganic compositions
  • H10N10/8556—Thermoelectric active materials comprising inorganic compositions comprising compounds containing germanium or silicon
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/071—Connecting or disconnecting
  • H10W72/075—Connecting or disconnecting of bond wires
  • H10W72/07541—Controlling the environment, e.g. atmosphere composition or temperature
  • H10W72/07554—Controlling the environment, e.g. atmosphere composition or temperature changes in dispositions
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/50—Bond wires
  • H10W72/531—Shapes of wire connectors
  • H10W72/536—Shapes of wire connectors the connected ends being ball-shaped
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/50—Bond wires
  • H10W72/541—Dispositions of bond wires
  • H10W72/547—Dispositions of multiple bond wires
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W72/00—Interconnections or connectors in packages
  • H10W72/50—Bond wires
  • H10W72/551—Materials of bond wires
  • H10W72/552—Materials of bond wires comprising metals or metalloids, e.g. silver
  • H10W72/5522—Materials of bond wires comprising metals or metalloids, e.g. silver comprising gold [Au]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S257/00—Active solid-state devices, e.g. transistors, solid-state diodes
  • Y10S257/93—Thermoelectric, e.g. peltier effect cooling

Definitions

• the invention relates to a thermoelectric element with at least one n layer and at least one p layer of one or more doped semiconductors, the n layer (s) and the p layer (s) being arranged with the formation of at least one pn junction, wherein at least one n-layer and at least one p-layer are electrically contacted and a temperature gradient is applied or tapped parallel (x direction) to the boundary layer between at least one n- and p-layer.
• thermoelectric effect has been known for more than 100 years. There is a wide range of materials that can be used for the direct conversion of a temperature gradient into electrical current. The technical implementation of this effect has always been based on a common basic structure (Fig. 1). Two different metals (a, b) or two different (n- and p-) doped semiconductors are connected at one, normally the hot end (temperature T,), and at the other, normally cold end (temperature T 2 ) the current can be tapped (resistor R as a symbolic consumer).
• thermoelectric elements are known, for example, from the documents EP 0 969 526 A1, JP 11195817 A, JP 10144969 A, JP 10022531 A, JP 10022530 A, JP 57-1276 (A), JP 07038158 A, JP 59-980 (A), JP 57-169283 (A), JP 4- 63481 (A) and US 5,009,717 are known, some of which have a conductive layer installed as a contact surface between the n and p layers in the region of the pn junction.
• thermoelectric elements have in common that the pn junction is formed only in a small area between the n and p layers, while the larger area between the n and p layers is an air gap or an insulating layer (JP-63481 ( A) and US 5,009,717) is formed.
• thermoelectric elements are assembled into a module in such a way that the individual elements are electrically connected in series but thermally in parallel. These modules can in turn be combined into larger units (Fig. 2).
• the materials used are selected based on the aspect of the maximum possible efficiency in the desired temperature range.
• thermoelectricity S ... Seebeck coefficient, p ... specific resistance, k ... thermal conductivity
• the object of the invention is therefore to provide an improved thermoelectric element.
• At least one pn junction is formed essentially along the entire preferably longest extent of the n layer (s) and the p layer (s) and thus essentially along their entire boundary layer.
• a central, fundamentally new idea is to use at least one pn junction, the temperature gradient running along the pn junction having a corresponding longitudinal extent.
• the pn junction is usually only formed in a small contact area with a constant temperature on the high temperature side of the thermoelectric element. It therefore only serves to improve the electrical contact between the n- and p-doped parts (layers).
• at least one pn junction is formed essentially over the entire extent of the n and p layers, a temperature gradient being applied along the pn junction interface.
• thermoelectric element according to the invention This creates a temperature difference along this elongated pn junction between two ends of a pn layer package, which means that the efficiency of the thermoelectric element according to the invention is significantly higher than in the prior art, which has no temperature gradient along and within the pn junction ,
• the more precise mode of operation is based on the different design of potential modulations in a pn junction at different temperatures, as will be explained below with reference to the description of the figures.
• the selective contacting of the n and p layers is important for the functional principle of this novel thermoelectric element. This can preferably be done either by alloying the contacts and the associated pn junctions or by directly contacting the individual layers.
• FIG. 1 shows a schematic diagram of a thermocouple according to the prior art
• FIG. 2 shows a thermoelectric module according to the prior art
• FIG. 3 shows the schematic diagram of an embodiment of a thermoelectric element according to the invention
• FIGS. 3a and 3b show other embodiments with different selective contacting of the n-layer or p-layer
• FIG. 4 shows the potential v in the region of the pn junction as a function of
• FIG. 5 shows two diagrams according to FIG. 4, but at different temperatures Ti and T 2 , 6 is a schematic three-dimensional representation of how the
• FIG. 7 shows a schematic representation of the development of an ambipolar diffusion
• FIG. 8 shows a diagram for the generation of electron-hole pairs
• FIG. 9 shows the recombination of electron-hole pairs by shrinking the
• FIG. 10 shows a favorable course of the temperature gradient over the thermoelectric element
• FIG. 11 shows a thermoelectric element with a width variation in the top view and the temperature gradients achieved therewith
• FIG. 12 shows an exemplary embodiment with two pn junctions
• FIG. 13 shows the construction of a thermoelectric module from a plurality of thermoelectric elements according to the invention
• FIG. 14 shows an exemplary embodiment with a highly doped n, an n, a p and a highly doped p layer.
• thermoelectric element The basic structure of a thermoelectric element according to the invention is shown in FIG. 3.
• An n-layer 1 and a p-layer 2 form a pn junction 3.
• the n-layer 1 and the p-layer 2 are selectively contacted via contacts 4 and 5, which lead to the ohmic consumer 7 (R) via a line 6.
• the temperature gradient (Ti denotes the higher temperature, T2 denotes the lower temperature) is applied in the direction parallel to the pn junction 3 (x direction).
• FIGS. 3a and 3b show exemplary embodiments for the selective contacting of the n-layer 1 and the p-layer 2.
• the layer thicknesses are shown significantly larger in comparison to the extension of the contact in the x-direction (about a factor of 100-1000).
• the p-layer 2 is contacted directly via a surface-deposited gold contact 5 (gold wire 6).
• An alloyed contact 4 ' is used to contact the n-layer.
• PbTe for example, indium can be used for the alloyed contact.
• the surface of the indium is used up and diffused into the layer package by heating.
• the PbTe-Indium alloy is of the n + type (highly doped).
• An ohmic contact to the n layer 1 and a pn junction to the p layer 2 are thus formed.
• the special highlight of the solution is that the nonlinear thermal properties of pn junctions are exploited.
• the temperature influences both the Fermi energy and (and above all) the energetic distribution of the charge carriers. In a pn transition this results in a change in the potential modulation.
• the potential modulation describes a modulation of the potential for charge carriers in semiconductor structures e.g. through a pn junction. For example, an electron is energetically at a higher potential in the p-layer than in the n-layer (for holes it is the other way round), the difference between these two potentials being the potential modulation. Since there is now an equilibrium value for the potential modulation for each temperature, the potential modulation changes when the temperature changes.
• a temperature gradient parallel to the boundary layer between the n- and p-layers therefore creates a lateral potential gradient in the x direction, thereby leading to ambipolar charge diffusion and thus to equalizing currents.
• the ambipolar charge carrier diffusion denotes the rectified diffusion of charge carriers of the same name in the rectified concentration gradient, as described with reference to FIG. 7.
• This internal compensating current can be conducted to the outside through the selective contacts (separate, non-conductive contacts for the n and p layers). This process will be briefly described in the following sections.
• the narrowband semiconductor PbTe (lead telluride) should be considered as an example:
• the charge carriers (n and p) are distributed so that a common Fermi energy E is formed (FIG. 4).
• the location of the Fermi energy is a function of the temperature and a potential modulation .DELTA.v arises, the
• FIG. 7 is a side view of FIG. 6 to illustrate this behavior (holes are marked with + and electrons with -).
• the ambipolar diffusion now has the consequence that in the region of the high temperature Ti of the pn layer package, charge carriers are removed and thus a charge deficit occurs, the shielding effect on the potential is reduced and the potential modulation increases. As a result, the local pn junction is no longer in thermal equilibrium and the thermal generation of electron-hole pairs outweighs the recombination (see arrows in FIG. 8).
• a circuit current flows in a layer package with at least one pn junction, as long as one area of the layer package is warmer than the rest, i.e. there is a temperature gradient parallel to the boundary layer. This circulating current transports heat.
• the temperature gradient parallel to the boundary layer between the n and p layers results in a generation of electron-hole pairs in the area of the high temperature and a recombination of these pairs in the area of the low temperature with the associated equalizing currents. Since the potential modulation between the n and p layers changes compared to the thermal equilibrium, a voltage between the n and p layers can be measured.
• contacts Since the potential modulation between the n and p layers changes and generation and recombination currents flow, contacts must be used which selectively contact only the n layer and other contacts which selectively contact only the p layer in order to use the currents to be able to dissipate to the outside.
• the selectivity can be ensured either by alloy formation (FIG. 3a) and formation of pn junctions or by direct contacting (FIG. 3, FIG. 3b) of the individual layers.
• the principle of the pn junctions is generally applicable, so all materials that form a pn junction can become interesting for thermoelectricity.
• thermoelectricity S ... Seebeck coefficient, p ... specific resistance, k ... thermal conductivity
• the high temperature area is very large compared to the low temperature area (flat gradient at high temperatures, steep gradient at low temperatures), then there is a larger area with generation of electron hole -Pairs (marked with +) and a small area with increased recombination (marked with -), i.e. an increase in the circulating currents and the efficiency of the overall system increases.
• Such a gradient can be achieved by various measures.
• One possibility is a variation in the composition of the material, so that a material with a higher thermal conductivity than the cold end is used at the hot end.
• a change in width can also bring about the desired temperature gradient, as is shown schematically in FIG. 11.
• a current draw at the cold end acts like an increased recombination and the internal potential gradients in the x direction are increased, which increases the ambipolar diffusion. That The ambipolar diffusion of the charge carriers is increased by a current drain, which means that the efficiency is increased by current drain.
• thermoelectric materials In addition, this concept opens up a wealth of new candidates for good thermoelectric materials.
• thermoelectric Seebeck
• thermoelectric elements are the preferred materials for thermoelectric elements due to their low thermal conductivity.
• Some examples of good thermoelectric materials are: Bi 2 Te 3 , PbTe, SiGe.
• Some ternary and quaternary compounds also show high efficiencies. Current research is mainly concerned with the search for these new materials.
• High to very high doping is necessary in order to keep the specific resistance as low as possible.
• the values for the doping depend of course on the material. As an example: with PbTe doping of 10 18 cm “3 and higher is necessary.
• the type of contact is extremely important for the new concept. Since the internal equalizing currents are to be branched off, the layers must be contacted selectively. This selective contacting can be done either by a direct and exclusive electrical connection to the desired layer or by alloying the contacts.
• the temperature gradient also plays a major role.
• the efficiency can be increased by a clever choice of the temperature distribution with a flat gradient in the area of the high temperatures and a steep gradient towards the end with the low temperature.
• the potential gradient that builds up internally can be increased, for example, by changing the potential modulation between the n and p layers due to a doping gradient become.
• the thermal conductivity can also be measured laterally (x-direction)
• the internal potential gradient is reinforced by the removal of charge carriers. This results in a positive feedback and the efficiency of the energy conversion is increased.
• n and p layers There must be at least one pn junction. However, more than one transition can also be used, with the n and p layers always having to alternate. 12 shows an embodiment with layer sequence pnp and two pn junctions pni and pn 2 .
• thermoelectric individual elements with a layer sequence as in FIG. 13 above are arranged thermally in parallel between two plates 8 and 9. Electrically, the individual elements are connected in series, specifically by means of cables 6 'running in a cross.
• the plates 8 and 9 serve for improved thermal coupling and can optionally also be omitted. They are preferably designed as good heat conductors and, to prevent electrical short circuits, are preferably constructed from ceramic, electrically nonconductive materials (for example Al 2 O 3 ).
• thermoelectric element consisting of two layers 1, 2 (n- and p-doped) and the pn junction formed in between
• two further layers 1 a, 2a add.
• a highly doped n-layer 1a is added to the existing n-layer 1 and a highly-doped p-layer 2a is added to the p-layer 2 in such a way that the following layer structure with 4 layers is obtained: n + - n - p - p + .
• the selective contacting remains identical to that of two layers.
• Thermoelectric generators for the direct conversion of a temperature difference into electricity. With this concept, any residual heat that would otherwise be unused can be used.
• One end means the end of a current flow and the other end is cold. This effect can be used for active cooling (for the

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• 2000
  • 2000-05-02 AT AT0076300A patent/AT410492B/de not_active IP Right Cessation
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