Nanowire based plasmonics

• US 20060289761A1
• Filed: 12/15/2005
• Published: 12/28/2006
• Est. Priority Date: 12/15/2004
• Status: Active Grant

• Current Assignee: Drexel University
• Original Assignee: Drexel University
• Inventors: Nabet, Bahram, Spanier, Jonathan E.
• Granted Patent: US 8,120,014 B2
• Time in Patent Office: Days
• US Class Current: 250/336.100
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: H01L 31/108 the potential barrier being of the Schottky type

Abstract

Nanoscaled, tunable detector devices for ultrasensitive detection of terahertz (THz) radiation based on the fabrication of one-dimensional (1D) plasma devices having clouds of strongly correlated and spatially confined electronic charge carriers are disclosed. These one-dimensional collective excitations (“plasmons”) are realized using coaxial semiconducting core-shell nanowires or by electrostatically confining a two dimensional charge to one dimension. By exploiting the properties of plasmons confined to reduced dimensions and under a selected device configuration, conventional limitations on carrier drift and transit times that dictate the speed and sensitivity of transistors can be circumvented, and detector sensitivity can be improved. 1D devices with sub-picosecond response times will be important for a range of applications in diverse areas such as remote sensing and imaging, molecular spectroscopy, biotechnology, and in a range of the spectrum that has been difficult to detect. In addition to electromagnetic radiation these devices can be used as detectors of charged particle perturbations.

Claims

1. A detector for detecting electromagnetic radiation and charged particles comprising:

an inner material;

an outer material surrounding said inner material;

a one-dimensional plasma confined in the detector;

and Schottky contacts associated with at least one of said inner and outer materials.

2. The detector of claim 1, wherein said one-dimensional plasma comprises charge carriers, wherein a resonant frequency response caused by electromagnetic radiation is produced in said charge carriers thereby forming one or more plasmons.

3. The detector of claim 1, wherein said electromagnetic radiation is terahertz radiation.

4. The detector of claim 2, further comprising tuning means for adjusting said resonant frequency.

5. The detector of claim 4, wherein said tuning means adjusts said resonant frequency by controlling charge carrier density.

6. The detector of claim 5, wherein said charge carrier density is adjusted by doping of said inner or outer material.

7. The detector of claim 5, wherein said charge carrier density is adjusted by changing a band-gap width.

8. The detector of claim 5, wherein said one-dimensional plasma comprises at least one energy gap and said charge carrier density is adjusted by periodic spatial modulation of said at least one energy gap.

9. The detector of claim 1, further comprising an additional one-dimensional plasma confined in the detector.

10. The detector of claim 9, wherein the collective charge carrier behavior of said additional one-dimensional plasma is different than the collective charge carrier behavior of said one-dimensional plasma.

11. A method for detecting electromagnetic radiation comprising the steps of:

forming a one-dimensional plasma; and

detecting plasmons caused by perturbations of said one-dimensional plasma by at least one of the group consisting of electromagnetic radiation and charged particles.

12. The method of claim 11, further comprising the step of establishing an electrical contact via blocking of Schottky contacts.

13. The method of claim 11, wherein said electromagnetic radiation is terahertz radiation.

14. The method of claim 11, wherein said step of detecting further comprises measuring a resonance frequency of said plasmons.

15. The method of claim 14, further comprising the step of tuning said resonance frequency by adjusting a charge carrier concentration in said one-dimensional plasma.

16. The method of claim 15, wherein said charge carrier concentration is adjusted by doping of a material used to confine said one-dimensional plasma.

17. The method of claim 15, wherein said charge carrier concentration is adjusted by changing a band-gap width.

18. The method of claim 15, wherein said one-dimensional plasma comprises at least one energy gap and said charge carrier concentration is adjusted by periodic spatial modulation of at least one said energy gap.

19. The method of claim 11, further comprising the step of forming an additional one-dimensional plasma.

20. The method of claim 19, wherein the collective charge carrier behavior of said additional one-dimensional plasma is different than the collective charge carrier behavior of said one-dimensional plasma.

21. The method of claim 11, wherein the step of forming said one-dimensional plasma is accomplished using a bottom-up approach.

22. The method of claim 11, wherein the step of forming said one-dimensional plasma is accomplish using a top-down approach.