Variable gap devices

• US 4,590,507 A
• Filed: 07/31/1984
• Issued: 05/20/1986
• Est. Priority Date: 07/31/1984
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Stavola, Michael J., Capasso, Federico, Gossard, Arthur C.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/636,155
• Time in Patent Office: 658 Days
• Field of Search: 357/4 SL, 357/4, 357/88, 357/28, 357/30, 357/16
• US Class Current: 257/185
• CPC Class Codes: H01L 29/157 Doping structures, e.g. doping superlattices, nipi superlattices delta doping in general H01L29/365
• CPC Class Codes: H10N 15/15 Selection of materials

Abstract

A device having a selectively doped varying bandgap region with pyroelectric characteristics is described which is useful as a photodetector or temperature sensor. A plurality of selectively doped regions forming a superlattice may also be used. Ferroelectric devices are also described.

Claims

1. A device comprising first and second semiconductor regions, first and second electrical contacts to said first and second regions, respectively, a third region between said first and second semiconductor regions, said third region comprising at least one graded bandgap region, a confining region adjacent said third region, said confining region and said third region forming a carrier confining energy well.

2. A device as recited in claim 1 in which said third region comprises a selectively doped region with the energy levels of the carriers and the dopant atoms being on different sides of the Fermi level at zero applied bias.

3. A device as recited in claim 2 in which said first and second contacts apply an electric field parallel to said third region.

4. A device as recited in claim 2 in which said first and second contacts apply an electric field perpendicular to said third region.

5. A device as recited in claim 2 further comprising an electrical contact to said third region, said contact applying an electric field perpendicular to said region of said superlattice.

6. A device as recited in claim 2 in which said first and second regions have the same conductivity type.

7. A device as recited in claim 2 in which said first and second regions have opposite conductivity type.

8. A device as recited in claim 2 in which said selectively doped region is doped n-type.

9. A device as recited in claim 2 in which said selectively doped region is doped p-type.

10. A device as recited in claim 2 in which said third region comprises a constant bandgap region and a varying bandgap region, said constant bandgap region being doped.

11. A device as recited in claim 10 in which said doping is n-type.

12. A device as recited in claim 10 in which said doping is p-type.

13. A device as recited in claim 11 in which said varying bandgap region has a local maximum in the conduction band above the Fermi level thereby forming two electron wells.

14. A device as recited in claim 13 in which said varying bandgap region comprises two local maxima in the conduction band above the Fermi level thereby forming two electron wells.

15. A device as recited in claim 2 in which said third region comprises a superlattice, said superlattice comprising a plurality of regions, said regions comprising a selectively doped region with the energy levels of the carriers and the dopant atoms being on different sides of the Fermi level at zero applied bias.

16. A device as recited in claim 15 in which said superlattice regions comprise a constant bandgap region and a varying bandgap region, said constant bandgap region being said selectively doped region.

17. A device as recited in claim 6 in which said varying bandgap regions have local maxima in the conduction band above the Fermi level thereby forming two electron wells.

18. A device as recited in claim 17 in which said varying bandgap regions comprise two local maxima in the conduction band above the Fermi level thereby forming three electron wells.

19. A device as recited in claim 15 further comprising an electrical contact to said superlattice region.