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Proceedings Paper

Quantum well intersubband THz lasers and detectors
Author(s): Richard A. Soref; Lionel R. Friedman; Gregory Sun; Michael J. Noble; L. R. Ram-Mohan
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Paper Abstract

This paper presents modeling and simulation results on Si- based quantum-well intersubband THz detectors and THz lasers (tasers) in the 3 to 10 THz range where the intersubband transition energy is 12 to 41 meV. The incoherent cryogenically cooled (4 K to 20 K) quantum well terahertz detector (QWTD) consists of p-type Si0.9Ge0.1 QWs with Si barriers on an Si substrate, or of p-Si0.85Ge0.15/Si on a relaxed Si0.97Ge0.03 buffer on Si. The QWTD senses THz radiation at normal incidence (the XY polarization on the HH1 to LH1 transition) or at edge- illumination (the Z polarization on the HH1 to HH2 transition). Resonant-cavity enhancement, coupling to Si THz waveguides, and integration with SiGe transistor preamplifiers appear feasible for QWTDs. The quantum staircase taser is a simplified far-infrared version of the quantum cascade laser in which each superlattice transfer region is replaced by a thin tunnel-barrier layer. We have adapted to group IV the III-V idea of Sun, Lu, and Khurgin; the `inverted mass taser'. On a Si0.81Ge0.19 substrate, we find that an inverted effective mass exists in LH1 at kg equals 0.013 angstroms-1 in 9-nm single- wells of Si0.7Ge0.3 with 5-nm Si barriers. Selective electrical injection of holes into LH1 at T equals 77 K is postulated. This offers local-in-k-space LH1-HH1 population inversion and tasing at 7.2 THz. Since the taser emission is XY-polarized, the active MQW staircase (a set of identical square QWs) is suitable for insertion into a vertical cavity surface-emitting taser. The VCSET would have resonator thickness of (lambda) /2n equals 6 micrometers , and Bragg mirrors constructed from SiO2/Si multilayers.

Paper Details

Date Published: 12 November 1999
PDF: 12 pages
Proc. SPIE 3795, Terahertz and Gigahertz Photonics, (12 November 1999); doi: 10.1117/12.370202
Show Author Affiliations
Richard A. Soref, Air Force Research Lab. (United States)
Lionel R. Friedman, Air Force Research Lab. (United States)
Gregory Sun, Univ. of Massachusetts/Boston (United States)
Michael J. Noble, Air Force Research Lab. (United States)
L. R. Ram-Mohan, Worcester Polytechnic Institute (United States)


Published in SPIE Proceedings Vol. 3795:
Terahertz and Gigahertz Photonics
R. Jennifer Hwu; Ke Wu, Editor(s)

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