Thermoelectric module with Si/SiGe and B4C/B9C super-lattice legs

• US 20050040388A1
• Filed: 04/05/2004
• Published: 02/24/2005
• Est. Priority Date: 12/12/2001
• Status: Active Grant

• Current Assignee: HI-Z Technology, Inc.
• Original Assignee: HI-Z Technology, Inc.
• Inventors: Elsner, Norbert B., Ghamaty, Saeid, Bass, John C.
• Granted Patent: US 7,038,234 B2
• Time in Patent Office: Days
• US Class Current: 257/15
• CPC Class Codes: H01L 29/155 Comprising only semiconductor materials H01L29/154 takes precedence
• CPC Class Codes: H10N 10/01 Manufacture or treatment
• CPC Class Codes: H10N 10/17 characterised by the structure or configuration of the cell or thermocouple forming the device
• CPC Class Codes: H10N 10/855 comprising compounds containing boron, carbon, oxygen or nitrogen
• CPC Class Codes: H10N 10/857 comprising compositions changing continuously or discontinuously inside the material
• CPC Class Codes: Y10S 257/93 Thermoelectric, e.g. peltier effect cooling

Abstract

A super-lattice thermoelectric device. The device is comprised of p-legs and n-legs, each leg being comprised of a large number of alternating layers of two materials with differing electron band gaps. The n-legs in the device are comprised of alternating layers of silicon and silicon germanium. The p-legs are comprised of alternating layers of B₄C and B₉C. In preferred embodiments the layers are about 100 angstroms thick. Applicants have fabricated and tested a first Si/SiGe (n-leg) and B₄C/B₉C (p-leg) quantum well thermocouple. Each leg was only 11 microns thick on a 5 micron Si substrate. Nevertheless, in actual tests operated the couple operated with an amazing efficiency of 14 percent with a T_h of 250 degrees C. Thermoelectric modules made according to the present invention are useful for both cooling applications as well as electric power generation. This preferred embodiment is a thermoelectric 10×10 egg crate type module about 6 cm×6 cm×0.76 cm designed to produce 70 Watts with a temperature difference of 300 degrees C. with a module efficiency of about 30 percent.

Claims

1. A thermoelectric module comprised of:

A) a plurality of n-legs comprised of very thin alternating layers of silicon and silicon germanium; and

B) a plurality of p-legs comprised of alternating layers of boron carbide comprise two different stoichiometric forms of boron carbide;

said p-legs and said n-legs being electrically connected to produce said thermoelectric module.

3. A thermoelectric module as in claim 1 wherein said alternating layers are deposited on a substrate.

7. A thermoelectric element as in claim 9, wherein said polyimide substrate is Kapton®

.

8. A thermoelectric element as in claim 10, wherein said polyimide substrate is Kapton®

film.

9. A thermoelectric element as in claim 1, wherein said very thin alternating layers are about 100 Angstroms thick.

10. A thermoelectric element as in claim 1, wherein said very thin alternating layers are each less than 200 Angstroms thick.

11. A thermoelectric element as in claim 1 wherein said very thin alternating layers are each less than 100 Angstoms thick.

12. A thermoelectric element as in claim 1 wherein said plurality of very thin alternating layers is about 3 million layers.

13. A thermoelectric element as in claim 1 wherein said plurality of very thin alternating layers more than 1 million layers.

14. A thermoelectric element as in claim 1 wherein said plurality of very thin alternating layers is at least 1250 layers.

2. A thermoelectric module as in claim 2 wherein said two different stoichiometric forms of boron carbide are B₄C and B₉C.

6. A thermoelectric module as in claim 6 wherein said substrate is a polyimide substrate.

4. A thermoelectric module as in claim 6 wherein said substrate is silicon.

5. A thermoelectric module as in claim 6 wherein said substrate is silicon film.

15. A method of producing thermoelectric modules comprising the steps of:

A) depositing on a thin substrate a very large number of very thin alternating layers of silicon and silicon germanium to form a Si/SiGe thermoelectric film;

B) forming a stack of said Si/SiGe films produces as in step A),

C) producing a plurality of Si/SiGe thermoelectric n-legs from said stacks of Si/SiGe films,

D) depositing on a thin substrate a very large number of very thin alternating layers of B₄C and B₉C to form a B₄C/B₉C thermoelectric film;

E) forming a stack of said B₄C/B₉C films produces as in step A),

F) producing a plurality of B₄C/B₉C thermoelectric p-legs from said stacks of B₄C/B₉C films,

G) forming a thermoelectric module from said plurality of Si/SiGe thermoelectric n-legs and said plurality of p-B₄C/B₉C thermoelectric legs,

said p-legs and said n-legs being electrically connected to produce said thermoelectric module.