Method for thermal energy-to-electrical energy conversion

Abstract

An improved method and apparatus for thermal-to-electric conversion involving relatively hot and cold juxtaposed surfaces separated by a small vacuum gap wherein the cold surface provides an array of single charge carrier converter elements along the surface and the hot surface transfers excitation energy to the opposing cold surface across the gap through Coulomb electrostatic coupling interaction.

Claims

1. A thermal-to-electric conversion method comprising: juxtaposing a relatively hot surface (S.sub.H) with a relatively cold surface (S.sub.C) separated by a gap (g) in the range of from 1 nanometer to 100 nanometers; providing the relatively hot surface (S.sub.H) with a hot side quantum well (W.sub.H) having an upper energy level (b) and a lower energy level (a), and connecting the hot side quantum well (W.sub.H) to a hot side reservoir (r.sub.A) of single charged carriers; providing the relatively cold surface (S.sub.C) with an array of converter elements, each converter element including a first cold side quantum well (W.sub.C1) having an upper energy level (2) and a lower energy level (1), and a second cold side quantum well (W.sub.Cr) having a single energy level (2.sup.1); connecting the first cold side quantum well (W.sub.C1) to a first cold side reservoir (r.sub.1) being maintained at relative ground potential, and connecting the second quantum well (W.sub.Cr) to a second cold side reservoir (r.sub.2); elevating a first single charge carrier from the hot side reservoir (r.sub.A) in the hot side quantum well (W.sub.H) by thermal energy from a lower energy level (a) to an upper energy level (b) and Coulomb coupling the change in energy level to a second single charge carrier from the first cold side reservoir (r.sub.1) in the first cold side quantum well (W.sub.C1); the elevated first single charge carrier relaxing from the hot side reservoir (r.sub.A) in the hot side quantum well (W.sub.H) from an upper energy level (b) to a lower energy level (a) causing the second single charge carrier from the first cold side reservoir (r.sub.1) in the first cold side quantum well (W.sub.C1) to be elevated from the lower energy level (1) to the upper energy level (2) of the first cold side quantum well (W.sub.C1), the first cold side reservoir being maintained at ground potential; tunneling by the second elevated single charge carrier through a potential barrier (PB) to the second cold side quantum well (W.sub.Cr) and transferring to a second cold side reservoir (r.sub.2) being maintained at an elevated potential (+); and connecting an electrical load between the second cold side reservoir (r.sub.2) and the first cold side reservoir (r.sub.1), creating a current through the electrical load by the movement of single charge carriers from the second cold side reservoir (r.sub.2) to the first cold side reservoir (r.sub.1).

2. The thermal-to-electric conversion method of claim 1, further minimizing the gap between the relatively hot surface and the relatively cold surface in the range between 1 nanometer and 100 nanometers to increase the amount of energy transferred across the gap by Coulomb coupling relative to the amount of energy transferred by transverse photon generation.

3. The thermal-to-electric conversion method of claim 2, further adjusting the gap between the relatively hot surface and the relatively cold surface to be less than about 50 nanometers.

4. The thermal-to-electric conversion method of claim 2 wherein the gap between the relatively hot surface and the relatively cold surface is adjustable.

5. The thermal-to-electric conversion method of claim 1 including promoting a single type carrier charge at a time.

6. The thermal-to-electric conversion method of claim 5 wherein the single carrier charge is selected from the group consisting of electrons and holes.

7. The thermal-to-electric conversion method of claim 1 wherein the converter elements comprise an array of semi-conductor elements that are chip-integrated along the relatively cold surface in a matrix substrate and interconnected by a network wherein the network is selected from the group consisting of conductors between multiple first cold side reservoirs and conductors between multiple second cold side reservoirs, positioned within the chip substrate to provide the appropriate connections between the elements of the array.

8. The thermal-to-electric conversion method of claim 7 further connecting the first cold-side reservoir conductors and second cold side reservoir conductors in the array to opposite sides of said electrical load.

9. The thermal-to-electric conversion method of claim 7 wherein the semi-conductor elements are selected from the group consisting of InSb, Ga .sub.0.31 In.sub.0.69 Sb, cadmium selenide, cadmium sulfide and cadmium telluride material.

10. The thermal-to-electric conversion method of claim 7 further selecting the material of the relatively hot surface from the group consisting of aluminum oxide, flat metal, metallic copper, semi-metal, and highly doped semiconductor material.

11. The thermal-to-electric conversion method of claim 7 wherein the cold side reservoir conductors are of doped n-type InSb.

12. The thermal-to-electric conversion method of claim 7 wherein the chip matrix substrate on the cold side is selected from the group consisting of GaSb, cadmium selenide, cadmium sulfide and cadmium telluride material.

13. The thermal-to-electric conversion method of claim 7 wherein the semi-conductor elements and the interconnecting network are integrated in the substrate, with some oriented parallel to the relatively cold surface, and some oriented horizontally and vertically oriented to the relatively cold surface.

14. The thermal-to-electric conversion method of claim 1 wherein the gap is selected from the group consisting of a vacuum gap and a gas gap.

15. The thermal-to-electric conversion method of claim 1 wherein the method functions as a refrigerator wherein the electrical load is a power source load.

16. The thermal-to-electric conversion method of claim 1 wherein the gap between the relatively hot surface and the relatively cold surface is sufficiently small so as to increase converted power per unit area due to Coulomb-coupling interactions.

17. The thermal-to-electric conversion method of claim 1, further comprising adjusting the gap between the juxtaposed relatively hot surface and relatively cold surface to be sufficiently small to minimize the effects of transverse photon generation relative to the amount of energy transferred by Coulomb coupling interaction.

18. The thermal-to-electric conversion method of claim 1, wherein the relatively hot surface temperature is about 1300 K and the relatively cold surface temperature is about 300 K.

19. The thermal-to-electric conversion method of claim 18, wherein the relatively hot surface temperature is less than 1300 K to enable functionality of quantum elements on the relatively hot surface.

20. The thermal-to-electric conversion method of claim 1, wherein the first cold side quantum well and the second cold side quantum well are quantum elements selected from the group consisting of quantum dots, bars and wires having dimensions of between 10 and 120 Angstroms.

21. The thermal-to-electric conversion method of claim 1, wherein an array of one energy level cold side quantum wells is positioned next to an interleaving array of two energy level cold side quantum wells to allow for tunneling therebetween.

22. The thermal-to-electric conversion method of claim 1, wherein the first cold side quantum well is a first quantum dot that has dimensions of 120 Angstroms by 100 Angstroms by 100 Angstroms, is comprised of InSb.

23. The thermal-to-electric conversion method of claim 1, wherein the second cold side quantum well is a second quantum dot that has dimensions of 50 Angstroms by 100 Angstroms by 100 Angstroms, and is comprised of GaInSb.

24. The thermal-to-electric conversion method of claim 1, wherein the first cold side quantum well is a first quantum dot and the second cold side quantum well is a second quantum dot, the first quantum dot being separated from the second quantum dot by 100 Angstroms.

25. The thermal-to-electric conversion method of claim 24, wherein the first cold side reservoir is positioned 50 Angstroms from the first quantum dot and the second cold side reservoir is positioned 50 Angstroms from the second quantum dot.

26. The thermal-to-electric conversion method of claim 1, wherein the relatively hot surface is selected from the group consisting of aluminum oxide, flat metal, metallic copper, semi-metal, and highly doped semiconductor material.

27. A thermal-to-electric conversion method comprising: juxtaposing a relatively hot surface (S.sub.H) and relatively cold surface (S.sub.C) separated by a small vacuum or gas-filled gap (g) in a 1 to 100 nanometer range; providing an array of interconnected quantum elements and associated reservoirs at the relatively cold surface (S.sub.C); disposing the quantum elements in multiple pairs of closely adjacent single charge converter elements including a first cold side quantum element (W.sub.C1) having two excitation level quantum states (1, 2) and a second cold side quantum element (W.sub.Cr) having a single excitation level quantum state (2.sup.1); arranging the multiple quantum element pairs serving as single charge carrier converter elements, wherein a single charge carrier in each interconnected first cold side quantum element (W.sub.C1) is elevated by Coulomb interaction with a charge carrier in a hot side quantum element (W.sub.Cr) on the relatively hot surface (S.sub.H) from a lower excitation level (1) to a higher excitation level (2) in a first cold side quantum element (W.sub.C1), and tunnels through a potential barrier (PB) from a relative ground potential to an excitation level (2.sup.1) of the second cold side quantum element (W.sub.Cr) maintained at an elevated potential (+) to an electrical load; and interspersing first cold side reservoirs (r.sub.1) at ground potential connected to the first cold side quantum element (WC1), second cold side reservoirs (r.sub.2) at an elevated potential, and buses having connections to the respective quantum elements of each single charge converter element pair and interconnected through a load between the first cold side reservoirs (r.sub.2) and the second cold side reservoirs (r.sub.2).

28. The thermal-to-electric conversion method of claim 27 wherein the quantum elements are selected from the group consisting of quantum dots, quantum wires and quantum wells.

29. The thermal-to-electric conversion method of claim 27 wherein each 1-excitation level quantum element of the pair is fixed at an elevated potential and positioned adjacent to the 2-excitation level quantum element of the pair to allow for tunneling therebetween.

30. The thermal-to-electric conversion method of claim 27 wherein the first cold side quantum element and associated buses are relatively grounded and a single charge carrier excited to the higher excitation level of the first cold side quantum element subsequently traverses into the excitation level of the second cold side quantum element.

31. The thermal-to-electric conversion method of claim 30 wherein electric fields are established between single charge carriers on the hot side and cold side such that electrostatic excitation transfer occurs across the gap.

32. The thermal-to-electric conversion method of claim 30 further comprising a set of reservoirs and busses connected to a higher potential than relative ground so that single charge carriers excited through Coulomb energy transfer subsequently tunnel to the excitation level of the second cold side quantum element before relaxing into the higher voltage reservoir and the bus connected to the load.

33. The thermal-to-electric conversion method of claim 32 wherein the reservoirs and busses are positioned about 50 Angstroms from the quantum elements at or near the relatively cold surface.

34. The thermal-to-electric conversion method of claim 32 wherein the quantum elements have at least one dimension of between about 120 Angstroms and about 10 Angstroms.

35. The thermal-to-electric conversion method of claim 34 wherein the single level quantum elements have at least one dimension from about 10 to about 120 Angstroms.

36. The thermal-to-electric conversion method of claim 27 wherein the second cold side quantum element is selected from the group consisting of Ga.sub.0.31In.sub.0.69Sb, cadmium selenide, cadmium sulfide and cadmium telluride.

37. The thermal-to-electric conversion method of claim 27 wherein the distance between the quantum elements is less than 100 Angstroms.

38. A thermal-to-electric conversion method comprising one or more converter elements, each converter element comprising: juxtaposing a relatively hot surface (S.sub.H) in relation to a relatively cold surface (S.sub.C), the relatively hot surface (S.sub.H) and the relatively cold surface (S.sub.C) being separated by a gap (g) of between 1 nanometer and 100 nanometers; introducing a hot side charge carrier (m.sub.2) into a hot side quantum well (W.sub.H) from a hot side reservoir (r.sub.A) and elevating the hot side charge carrier from a lower potential energy level (a) to an upper potential energy level (b) by thermal energy; positioning a first quantum well (W.sub.c1) having a lower potential energy level (1) and an upper potential energy level (2) at or near the relatively cold surface (S.sub.C); introducing a single charge carrier into the lower potential energy level (1) of the first quantum well (W.sub.C1) on or near the relatively cold surface (S.sub.C) from a first cold side reservoir (r.sub.1); transferring excitation energy by Coulomb electrostatic coupling between the hot side charge carrier in the hot side quantum well (W.sub.H) and the single charge carrier in the first quantum well (W.sub.C1), wherein the single charge carrier is elevated from the lower potential energy level (1) to the upper potential energy level (2) in the first quantum well (W.sub.C1) and the hot side charge carrier relaxes from the upper potential energy level (b) to the lower potential energy level (a) in the hot side quantum well (W.sub.H); the single charge carrier at the upper potential energy level (2) in the first quantum well (W.sub.C1) tunneling through a potential barrier (PB) to a second quantum well (W.sub.Cr) at an upper potential energy level (2.sup.1) and is received by a second cold side reservoir (r.sub.2) maintained at an elevated potential (+) relative to a potential of the first cold side reservoir; and the single charge carrier passing through an electrical load from the second cold side reservoir (r.sub.2) to the first cold side reservoir (r.sub.1), wherein the single charge carrier in the first cold side reservoir (r.sub.1) is at the lower potential energy level (1).

39. The thermal-to-electric conversion method of claim 38, wherein the first cold side reservoir is at relative ground potential.

40. The thermal-to-electric conversion method of claim 38, wherein the first quantum well and second quantum well comprise single charge carrier quantum dots.

41. The thermal-to-electric conversion method of claim 38, wherein the first cold side reservoir is a conductor of a conducting network interconnecting multiple first quantum wells in an array of first quantum wells distributed along the relatively cold surface.

42. The thermal-to-electric conversion method of claim 38, wherein the single charge carrier is selected from the group consisting of holes and electrons.

43. The thermal-to-electric conversion method of claim 38, where the juxtaposed relatively hot surface and relatively cold surface are adjusted to be sufficiently close in a near surface electric field such that the dipole interaction therebetween is dominated by Coulomb electrostatic interaction.

44. The thermal-to-electric conversion method of claim 43, further comprising adjusting the gap between the juxtaposed relatively hot surface and relatively cold surface to be sufficiently small to minimize the effects of transverse photon generation relative to the amount of energy transferred by Coulomb coupling interaction.

45. The thermal-to-electric conversion method of claim 38, wherein the relatively hot surface temperature is about 1300 K and the relatively cold surface temperature is about 300 K.

46. The thermal-to-electric conversion method of claim 45, wherein the relatively hot surface temperature is less than 1300 K to enable functionality of quantum elements on the relatively hot surface.

47. The thermal-to-electric conversion method of claim 38, wherein the first quantum well and the second quantum well are quantum elements selected from the group consisting of quantum dots, bars and wires having dimensions of between 10 and 120 Angstroms.

48. The thermal-to-electric conversion method of claim 38, wherein an array of one energy level quantum elements is positioned next to an interleaving array of two energy level quantum elements to allow for tunneling therebetween.

49. The thermal-to-electric conversion method of claim 38, wherein the first quantum well is a first quantum dot that has dimensions of 120 Angstroms by 100 Angstroms by 100 Angstroms, is comprised of InSb and has energy separation of the potential energy levels therein of 0.2electron volts.

50. The thermal-to-electric conversion method of claim 38, wherein the second quantum well is a second quantum dot that has dimensions of 50 Angstroms by 100 Angstroms by 100 Angstroms, and is comprised of GaInSb.

51. The thermal-to-electric conversion method of claim 38, wherein the first quantum well is a first quantum dot and the second quantum well is a second quantum dot, the first quantum dot being separated from the second quantum dot by 100 Angstroms.

52. The thermal-to-electric conversion method of claim 51, wherein the first cold side reservoir is positioned 50 Angstroms from the first quantum dot and the second cold side reservoir is positioned 50 Angstroms from the second quantum dot.

53. The thermal-to-electric conversion method of claim 38, wherein the relatively hot surface is selected from the group consisting of aluminum oxide, flat metal, metallic copper, semi-metal, and highly doped semiconductor material.

54. A method for converting thermal-to-electric energy comprising: juxtaposing a relatively hot surface (S.sub.H) and a relatively cold surface (S.sub.C) and separating the surfaces by a gap (g), the gap being selected from the group consisting of a vacuum gap and a gas gap; positioning the juxtaposed surfaces to be sufficiently close in a near surface electric field such that a dipole interaction there between is enhanced by a Coulomb electrostatic coupling interaction whereby the Coulomb interaction transfers thermal energy in a conversion directly by quantum element interactions along the cold surface (S.sub.C). carrying a chip array of pairs on the cold surface of closely adjacent single-level and higher-level excitation quantum state elements that serve as an array of single-charge carrier converter elements; and electrostatically transferring excitation energy from the relatively hot surface (S.sub.H) to the juxtaposed cold surface single charge converter elements across the gap (g).

55. The method for converting thermal-to-electric energy of claim 54, further comprising selecting the relatively hot surface (S.sub.H) from the group consisting of aluminum oxide, flat metal, metallic copper, semi-metal, highly doped semiconductor, and quantum elements selected from the group consisting of hot side quantum wires, hot side quantum dots, hot side quantum reservoirs (r.sub.A), and hot side quantum wells (W.sub.H).

56. The method for converting thermal-to-electric energy of claim 55, wherein the hot side quantum wells (W.sub.H) have an upper energy level (b) and a lower energy level (a), the hot side quantum wells (W.sub.H) connecting to the hot side reservoirs (r.sub.A) containing single charge carriers.

57. The method for converting thermal-to-electric energy of claim 54, wherein the relatively hot surface (S.sub.H) is selected for the group consisting of an insulator, a semi-conductor and a metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features, aspects and advantages of the present invention will become better understood with regard to the following description and accompanying drawings wherein:

(2) FIG. 1 of which is a basic schematic diagram of an idealized conception underlying the invention;

(3) FIG. 2 is an expanded isometric schematic view of a preferred device for practicing the methodology of the invention embodying solid state conversion arrays as implementation;

(4) FIG. 3 is a similar diagram of such an array of the novel thermal-to-electric converter elements of the type shown in FIG. 2; and

(5) FIGS. 4 and 5 are respective load power density and efficiency of performance graphs attainable with such an embodiment of the invention.

DETAILED DESCRIPTION

(6) Turning first to the roadmap of our said FIG. 1, this involves an idealized theoretical explanatory scheme consisting of a hot-side surface S.sub.H and a juxtaposed cold-side carrier charge-to-electricity converter surface S.sub.C separated by a small vacuum gap g. On the cold side, there is schematically shown a first quantum well W.sub.C1 having a lower electron potential level 1 and an upper level 2 and wherein an electron is introduced or supplied into the lower level or state 1 from a source of electrons called a reservoir r.sub.1, which may be at relative ground potential. As later explained, in practical implementation, the well W.sub.C1 may be inherently provided in a quantum dot, such as an appropriate semi-conductor dot, and the electron reservoir r.sub.1 may be a conductor of a conducting network interconnecting such dots in an array or matrix of dots distributed along the cold-side S.sub.C as later more fully described in connection with the embodiments of FIGS. 2 and 3.

(7) Electrostatic coupling to charges on the hot side surface S.sub.H produces a quantum-correlation. This appears schematically in FIG. 1 as a well W.sub.H with two levels connected to an electron reservoir r.sub.a. As an electron is supplied from the cold-side reservoir r.sub.1 to the cold-side level 1 of the well W.sub.C1, accordingly, Coulomb electrostatic coupling between that electron and a charge on the hot side produces a quantum correlation between the cold side electron and such carrier, providing electrostatic interaction U that leads to excitation energy transfer from the hot side to the cold side, thereby elevating the electron in the cold-side well W.sub.C1 up to higher potential level or state 2, as indicated by the upward arrow portion shown below the symbol U. From this upper state 2, the electron may tunnel, as shown schematically at V, through a potential barrier PB to a matched level 2.sup.1 in a second quantum dot well W.sub.cr on its way to a second reservoir r.sub.2 which is at elevated voltage relative to ground, as schematically illustrated at +. The well W.sub.cr permits only one levellevel 2.sup.1. The two cold-side reservoirs r.sub.1 and r.sub.2 are connected together through an electrical load, so-labeled. Thus, when elections are promoted in the first quantum well W.sub.C1, they have the possibility of tunneling to the second well W.sub.cr and then continuing on to do electrical work before ending up in the first reservoir r.sub.1 at ground.

(8) The levels of the hot-side relax to an electron reservoir r.sub.A comprising a continuum of excitation levels, wherein the level a is coupled to each level in the reservoir with matrix element m.sub.2 and m.sub.3.

(9) Electric fields between an electron on the hot side well W.sub.H and an electron on the cold side, couple the product states |b>|1> and |a>|2> with coupling U such that excitation transfer can occur across the gap g. Level 1 of the well W.sub.C1, in turn, relaxes to reservoir r.sub.1 with matrix element m.sub.1 and level 2.sup.1 of well W.sub.cr relaxes to reservoir r.sub.2 with matrix element m.sub.4.

(10) In Coulomb-coupling energy is transferred from a hot-side electron to a cold-side electron through the Coulomb force between the two electrons. The basic mechanism of the device is that high temperature on the hot side results in excited electrons in the hot-side image, with excitation transferred via electrostatic interaction coupling U (between the hot-side charge, which is itself coupled to excited electrons and phonon modes, and the cold-side electron) to promote a cold-side electron from level 1 to level 2 in well W.sub.C1. The invention of FIG. 1 can also functions as a refrigerator where the load is a power source providing energy into the system to cool the cold-side down and to heat up the hot-side.

(11) In summary, thus, an electron reservoir on the cold side supplies an electron to a lower state; and coupling with the hot side causes the electron to be promoted to an excited state, and then the electron proceeds to a second electron reservoir at elevated potential. An electrical load connected between the two reservoirs can be driven from the electrical current caused by the promoted electrons. Such a scheme can work with either electrons or holes. We have called it a single carrier converter since, in accordance with the invention, it is only a single carrier that is promoted at a time (either an electron or a hole but not both), as opposed to a photovoltaic in which electron-hole pairs are created and photon exchange coupling occurs, namely an electron on the hot side emits a photon and an electron on the cold side accepts the photon. This photon exchange coupling is in contrast to Coulomb coupling. The magnitude of the photon exchange coupling and the Coulomb coupling have different distance dependencies (that is, the distance between the hot-side and the cold-side) where Coulomb coupling has a 1/R.sup.3 dependence on distance while the photon exchange coupling has a 1/R dependence. Coulomb coupling dominates over the photon exchange coupling at narrow distances roughly shorter than the wavelength corresponding to the energy separation of the cold-side single level and higher level excitation quantum state elements divided by 2 or at distances roughly shorter than /2. At larger distances, the Coulomb coupling decays rapidly.

(12) FIG. 2 presents an exploded view of a preferred physical structure of a thermal-electric converter constructed in accordance with the invention to operate in accordance with the methodology thereof as outlined in FIG. 1. As explained previously, the cold-side surface S.sub.c of the device is shown juxtaposed to the hot-side heat emitter surface S.sub.H with a small vacuum gap g there between. The cold-side converter comprises an array of appropriate semi-conductor small elements or dots, two of which are shown as Dot 1 and Dot 2, implemented as by well-known chip technology and in a chip substrate matrix schematically illustrated by S. In practice, these semi-conductor converter dots may assume any desired geometry, such as the rectangular boxes or bar elements shown, supporting and serving as quantum-confined electron energy excitation state wells (W.sub.C1 and W.sub.cr, FIG. 1) along (at or near) the surface S.sub.c. Other forms of these semi-conductor elements may include small cylinders or wires, small quantum-well sheets or even molecules. The array of dot elements or the like will be conductor-interconnected, as earlier mentioned by, a network of conductors feeding and outputting electrons to and from the respective elements (reservoir r.sub.1, r.sub.2, etc. in FIG. 1) interconnecting the array of dot elements in series and/or in parallel fashion, as appropriate, and also formed into the substrate matrix S of the converter chip side of the device. In the device of FIG. 2, moreover, segments of these electron reservoir conductors are shown at Reservoir 1 (r.sub.1 in FIG. 1) and at Reservoir 2 (r.sub.2 in FIG. 1) as rectangular cross-section bus portions.

(13) In accordance with the invention, in an appropriately dimensioned structure, the charge in the quantum dot on the cold side surface S.sub.c will couple to a charge on the nearby conductive hot-side surface S.sub.H, providing a coupling to surface currents, resulting in the two-level system model of the invention herein presented.

(14) In the device of FIG. 2, the hot side surface S.sub.H may accordingly be a simple flat surface comprising aluminum oxide or a metal, semi-metal or highly doped semiconductor. The metal surface has surface charges and the charges act as an effective dipole with zero energy separation that is coupled to thermally excited electrons and phonons. Across the gap g, the cold-side is shown as comprising the before-mentioned two quantum dots on the surface S.sub.C; Dot 1 having two levels (well W.sub.C1 of FIG. 1) and they couple to the hot-side dipole via the electrostatic Coulomb coupling interaction before described. Dot 2 has one level (in well W.sub.cr of FIG. 1) and it couples to the excited upper level of Dot 1 (state 2 in well W.sub.C1 of FIG. 1) through the tunneling (V). The lower level of Dot1 (level 1 in well W.sub.C1), as before stated, relaxes to the ground voltage conductor Reservoir 1 (r.sub.1 in FIG. 1). The Dot 2 level relaxes to conductor Reservoir 2 which is at the elevated voltage +. Reservoir conductor 1 is shown having a horizontal branch bus portion extending from the vertical leg of the bus conductor in order to couple the lower level of Dot 1, the branch being oriented horizontally to Dot 1 and facing the center of Dot 1, with a distance. Reservoir conductor 2 is shown parallel to Dot 1 and it runs parallel along the surface S.sub.C next to Dot 2, with a distance. Where desired, these dot and conductor elements may also be oriented at other angles, including substantially perpendicular to the plane of the surface S.sub.C.

(15) The converter elements may comprise an array of semi-conductor elements that are chip-integrated along the cold surface in a matrix substrate and interconnected by a network of electron reservoir conductors or buses, interleaved within the chip substrate to provide the appropriate series and/or parallel connections amongst and between the elements of the array.

(16) The cold-side structure is repeated as an array over the surface S.sub.C as shown in FIG. 3, with the Reservoir 1 conductor buses linked together, and the Reservoir 2 conductor buses linked together, and within Reservoirs 1 and 2 connected through the load as in FIG. 1.

(17) In one embodiment, a simulated specific structural design of this implementation, we obtained the following exemplary results. The temperature on the hot-side is 1300K, and that on the cold-side, 300K. Dot 1 has xyz dimension 120 100 100 and is of the preferred material InSb. The energy separation of the Dot 1 levels is 0.2 eV. The relaxation time of InSb at 0.2 eV is 1.Math.ps. The hot-side is metallic copper, in this equipment, of which relaxation time at 0.2 eV is 0.57 fs. In one embodiment, Dot 2 has dimension 50 100 100 and is horizontally pointing to the top part of Dot 1. (FIG. 2 is not drawn to scale). Dot 2 is of material Ga.sub.0.31In.sub.0.69Sb but may also be comprised of other materials as described herein. The distance between Dot 1 and Dot 2 is 100 . Reservoir 1 branch is horizontally positioned 50 away from the center of Dot 1. Reservoir 2 is located 50 next to Dot 2. Both reservoirs are preferably made up of n-type InSb doped such that its relaxation time at 0.2 eV is 10 ps. The relaxation time for an n-type InSb with doping level 310.sup.17cm.sup.3 at 0.2 eV is 52 ps, and it is expected that the relaxation time will decrease to zero as the doping increases, since this is the behavior at DC. Therefore there exists a doping level with any desired relaxation time. The surrounding matrix material substrate on the cold side may be GaSb. In other embodiments, the quantum element dimensions, spacing there between and materials may differ as described herein.

(18) Electrostatic interaction increases with smaller vacuum gap thickness. Radiative heat transport occurs between the hot and cold region, however, if two surfaces are close together, the amount of useful power transferred from the hot to cold side increases much more rapidly because of the effects of Coulomb coupling. In a vacuum, Coulomb coupling dominates over photon contribution by the absorption wavelength in the divided by 2. For example, the absorption wavelength corresponding to 0.2 eV is 6.2 m, and hence the gap should be below about 1 m for that case in a vacuum. in the calculations, Coulomb coupling dominates below about 500 Angstroms because of the dielectric constants. Therefore if the gap between the hot surface and the cold surface is sufficiently small, the effects of transverse photon generation are minimized relative to the amount of thermal energy transferred by the Coulomb interaction. The converted power per unit area is improved as the gap becomes smaller at very small distances due to Coulomb-coupling interactions. The amount of power converted per unit area is important since it fundamentally impacts the cost of power conversion. If the gap between the hot surface and the cold surface is sufficiently small the converted power per unit area will be increased due to Coulomb-coupling interactions. Gaps below 50-100 nanometers with a lower limit as small as practically possible such as 1 nanometer may facilitate the maximization of the amount of thermal energy transferred by the Coulomb interaction.

(19) Shown in FIG. 4 and FIG. 5 are the power on load density and efficiency, respectively, as a function of voltage for the device. An initial estimate for maximum power per unit active area is 202 W/cm.sup.2 occurring at voltage 107 mV. FIG. 5 shows that the maximum efficiency 49.8% occurs at voltage 129 mV.

(20) While the invention has been described with references to its preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the invention without departing from its essential teachings.