Batteries: thermoelectric and photoelectric – Thermoelectric – Processes
Reexamination Certificate
1999-11-17
2002-06-11
Bell, Bruce F. (Department: 1741)
Batteries: thermoelectric and photoelectric
Thermoelectric
Processes
C136S203000, C136S205000, C252S06230T, C438S022000, C438S478000, C257S026000, C257S185000, C257S191000, C257S442000, C257S443000, C257S449000, C257S467000
Reexamination Certificate
active
06403874
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to electronic devices, and more specifically to the use of semiconductor materials to fabricate thermionic coolers and generators.
2. Description of Related Art
The use of electronics to transport heat to and away from certain areas has expanded in recent years due to increased packing densities and hostile environments. For cooling applications, thermoelectric (TE) coolers have been used to cool areas both in electronic and nonelectronic applications. TE coolers typically include a p-type doped region alternatively connected to an n-type doped region, which creates cooling effects at one metal-doped region junction and heating effects at the other metal-doped region junction, depending on the direction of the current through the device.
However, TE coolers are limited in their overall efficiency by the bulk properties of the materials used in the TE cooler. Further, the reliability of assemblies of many elements, such as in TE coolers, is often not sufficient for many applications. The cost of TE coolers has not dropped at the same rate as other electronic devices such as transistor circuits, lasers and detectors, because TE cooler elements are not fabricated using high volume planar integrated circuit technology. Further, TE coolers that can generate a large cooling effect tend to be large devices, typically 1 cm×1 cm or larger, and are slow cooling devices, and thus, are not acceptable in small electronic devices.
From the foregoing, it can be seen then that there is a need for improved electronic coolers. It can also be seen then that there is a need for better electronic cooler fabrication techniques. It can also be seen that there is a need for low cost electronic coolers. It can also be seen that there is a need for more space efficient electronic coolers. It can also be seen that there is a need for more energy efficient electronic coolers. It can also be seen that there is a need for coolers with faster response times. It can also be seen that there is a need for more reliable electronic coolers. It can also be seen that there is a need for electronic coolers that reach lower temperatures.
SUMMARY OF THE INVENTION
The present invention minimizes the above-described problems by using bandgap engineering and modulation doping to fabricate small thermionic coolers that operate at room temperature. By using proper materials and geometries, efficient and space conserving thermionic cooler elements which can reach lower temperatures are fabricated in a cost-effective manner. Further, these coolers can have a much faster response.
The present invention comprises a method and apparatus for theomionic cooling. The method of the present invention comprises growing two semiconductor layers. The second layer has a variable conduction bandedge as a function of distance (for the case of electron transport) which has a Fermi level on the order of k
B
T from the bandedge of the semiconductor layer. This structure allows for selective thermionic emission of high energy carriers from cathode to anode that suppresses the reverse current, and creates a cold junction at the cathode and a hot junction at the anode. Using the same device in contact with a hot and a cold bath will create a thermionic generator.
One object of the present invention is to provide better electronic cooler fabrication techniques. It is a further object of the invention to reduce electronic cooler fabrication costs. It is a further object of the invention to make more efficient electronic coolers which reach lower temperatures. It is a further object of the invention to make electronic coolers that have a faster response time.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.
REFERENCES:
patent: 4353081 (1982-10-01), Allyn et al.
patent: 4694318 (1987-09-01), Capasso et al.
patent: 5955772 (1999-09-01), Shakouri et al.
N. W. Ashcroft, et al., Solid State Physics, manual, 1976, pp. 318-319, 320-321, 362-363.
D. A. Broido et al., “Effect of superlattice structure on the thermoelectric figure of merit:”, The American Physical Society (Physical Review B.), vol. 51, No. 19, May 15, 1995, pp. 13797-800.
D. A. Broido et al., “Comment of Use of quantum well superlattices to obtain high figure of merit from nonconventional thermoelectric materials”, [Appl. Phys. Lett. 63, 3230 (1993)], Applied Physics Letters, vol. 67, No. 8, Aug. 21, 1995, pp. 1170-1171.
D. A. Broido et al., “Thermoelectric figure or merit of quantum wire superlattices”, Applied Physics Letters, Jul. 3, 1995, vol. 67, No. 1, 100-102.
P.J. Lin-Chung, et al., “Thermoelectric figure of merit of composite superlattice systems”, Physical Review B (condensed matter), vol. 51, No. 19, May 15 1995, pp 13244-8.
A. J. Dekker, “Thermionic Emission”, McGraw-Hill Encyclopedia of Science & Technology, 6thEdition, 1987, vol. 18, pp 272-273.
L. D. Hicks, et al., “Effect of quantum-well strucutres on the thermoelectric figure of merit”, Physical Review B (condensed matter), vol. 47, No. 19, May 15, 1993, pp. 12727-31.
L. D. Hicks, et al. “Thermoelectric figure of merit of a one-dimensional conductor”, Physical Review B (condensed matter), vol. 47, No. 24, Jun. 15, 1993, 16631-4.
L. D. Hicks, et al. “Use of Quantum-well superlattices to obtain a high figure of merit from nonconventional thermoelectric materials”, Applied Physics Letters, vol. 63, No. 23, Dec. 6, 1993, 3230-2.
L. D. Hicks, et al., Experimental study of the effect of quantum-well structures on the thermoelectric figure of merit, Phyical Review B (condensed matter), vol. 53,No. 16,R10493-6.
J. M. Houston, “Theoretical efficiency of the thermionic energy converter”, Journal of Applied Phyics, vol. 30 No. 4, Apr. 1959, pp. 481-487.
L .W. Whitlow, et al., “Superlative applications to thermoelectricity”, Journal of Applied Physics, Nov. 1, 1995, vol. 78, No. 9, 5460-5466.
L .W. Whitlow, et al., “Superlative applications to thermoelectricity”, Journal of Applied Physics, Nov. 1, 1995, vol., 78, No. 9, 5460-5466.
G. D. Mahan, et al., “Thermionic refrigeration”, Journal of Applied Physics, vol. 76, No. 7, Oct. 1, 1994, 4362-6.
Sofo,J.O., “Thermoelectric figure of merit of superlattices”, Applied Physics Letters, vol. 65, No. 21, Nov. 21, 1994, 2690-2.
D.M. Rowe, et al., “Multiple Potential Barriers as a Possible Mechanism to Increase the Seebeck Coefficient and Electrical Power Factor”, Thirteenth International Conference on Thermoelectrics, Kansas City, Mo. USA, Aug. 30-Sep. 1, 1994.).
K. K. Ng, “Complete Guide to Semiconductor Devices,” McGraw-Hill, 1995, pp. 48-55.
Mahan, G.D. et al., “Multilayer thermionic refrigerator and generator,” Journal of Applied Physics, vol. 83, No. 9, May 1, 1998, pp. 4683-4689, XP-000956318.
Mahan, G.D. et al., “Multilayer Thermionic Refrigeration,” Physical Review Letters, vol. 80, No. 18, May 4, 1998, pp. 4016-4019, XP-000956428.
Shakouri, Ali et al., “Heterostructure integrated thermionic coolers,” Applied Physics Letters, vol. 71, No. 9, Sep. 1, 1997, pp. 1234-1236, XP-000720237.
Bowers John E.
Shakouri Ali
Bell Bruce F.
Gates & Cooper LLP
Parsons Thomas H
The Regents of the University of California
LandOfFree
High-efficiency heterostructure thermionic coolers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High-efficiency heterostructure thermionic coolers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High-efficiency heterostructure thermionic coolers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2948665