Resonant tunneling transistor

• US 4,849,799 A
• Filed: 08/18/1986
• Issued: 07/18/1989
• Est. Priority Date: 07/31/1986
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.), Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: French, Harry T., Kiehl, Richard A., Gossard, Arthur C., Sen, Sustana, Capasso, Federico, Hutchinson, Albert L.
• Primary Examiner(s): James, Andrew J.
• Assistant Examiner(s): Jackson, Jr., Jerome
• Application Number:
  US06/897,378
• Time in Patent Office: 1,065 Days
• Field of Search: 357/45 L, 357/34, 357/30, 357/4, 307/474
• US Class Current: 257/25
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01L 29/7311 Tunnel transistors
• CPC Class Codes: H01L 29/7376 Resonant tunnelling transistors

Abstract

A resonant-tunneling, heterostructure bipolar transistor having a quantum well between emitter contact and collector region is described. In one embodiment, a compositionally graded portion of the emitter region is adjacent to the base region, and there is a double barrier in the base region. In another embodiment the quantum well is defined by the emitter and a potential barrier in the base region. Further embodiments have a quantum well between emitter and collector regions or else within the emitter region.

Claims

1. A heterostructure bipolar device comprising:

an emitter region having a first conductivity type and a first composition and bandgap profile;

a base region having a second conductivity type and a second composition and bandgap profile;

a collector region having said first conductivity type and having a third composition and bandgap profile;

first, second, and third electrical contracts to said emitter, base, and collector regions, respectively;

a quantum well between said collector region and said electrical contact to said emitter region, said quantum well being the only quantum well between said collector region and said electrical contact to said emitter region.

said device being capable of operating such that there are first and third base-emitter voltages and a second base-emitter voltage intermediary to said first and third base-emitter voltages such that, at said first, second, and third base-emitter voltages, the bottom of the conduction band in at least a portion of said emitter region is blow, at, and above, respectively, a quantum resonance of said quantum well, said portion being between said first electrical and said quantum well.

2. A device as recited in claim 1 in which, at said first and third base-emitter voltages, the bottom of the conduction band in at least a portion of said emitter region is below and above, respectively, a plurality of quantum resonances of said quantum well, said portion being between said first electrical contact and said quantum well.

3. A device as recited in claim 1 in which said quantum well is in said emitter region.

4. A device as recited in claim 1 in which said quantum well is between said emitter region and said collector region.

5. A device as recited in claim 4 in which said quantum well is in said base region.

6. A device as recited in claim 4, said device comprising a region intermediary to said emitter region and said base region, and said quantum well being in said intermediary region.

7. A device as recited in claim 1 in which said first conductivity type is n-type.

8. A device as recited in claim 1 in which said quantum well is a parabolic well.

9. A device as recited in claim 1 in which said collector region and said base region form a heterojunction which is such that the conduction band of the base region is below the conduction band of the collector region, and the valence band of the base region is above the valence band of the collector region.

10. A device as recited in claim 9 in which the edges of said quantum well are defined by two heterojunctions.

11. A circuit comprising a plurality of devices as recited in claim 1, and further comprising a resistive network connected to said second electrical contact, said network having a plurality of inputs.

12. A circuit comprising a plurality of devices as recited in claim 1, said devices being connected in parallel, further comprising a voltage scaling network, said network being connected to said second electrical contact.

13. A circuit comprising a device as recited in claim 1, further comprising means for maintaining said base-collector junction at fixed bias, and resistance connected to said third electrical contact.

14. A device as recited in claim 5, said device comprising means for tunneling injection of minority carriers into said quantum well, and said device having structure such that, for at least some operation condition, the conduction band of a portion of said base region adjoining said emitter region is essentially at the same level as the bottom of the ground-state subband of said quantum well.

15. A device as recited in claim 14, said portion of said base region not being electrically contacted.

16. A device as recited in claim 14, said conduction band lying below said bottom of the ground-state subband not by more than 5 kT.

17. A device as recited in claim 1, said quantum well being defined by potential barriers.

18. A device as recited in claim 17 in which said potential barriers are undoped.

19. A device as recited in claim 17 in which said quantum well is undoped.

20. A device as recited in claim 4, one side of said quantum well being defined by the heterojunction formed by said emitter region and said base region.

21. A heterostructure bipolar photodetector device comprising:

an emitter region having a first conductivity type and a first composition and bandgap profile;

a base region having a second conductivity type and a second composition and bandgap profile;

a collector region having said first conductivity type and having a third composition and bandgap profile;

first, second, and third electrical contacts to said emitter, base, and collector regions, respectively;

a quantum well between said collector region and said electrical contact to said emitter region, said quantum well being the only quantum well between said collector region and said electrical contact to said emitter region,

said device being capable of operating such that there are first and third base-emitter voltages and a second base-emitter voltage intermediary to said first and third base-emitter voltages such that, at said first, second, and third base-emitter voltages, the bottom of the conduction band in at least a portion of said emitter region is below, at, and above, respectively, a quantum resonance of said quantum well, said portion being between said first electrical contact and said quantum well.