Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session X39: Focus Session: Physics & Technology of III-V Semiconductors in Infrared & THZ Imaging I |
Hide Abstracts |
Sponsoring Units: FIAP Chair: Gamani Karunasiri, Naval Postgraduate School Room: Colorado Convention Center 502 |
Friday, March 9, 2007 8:00AM - 8:36AM |
X39.00001: High Performance Thermal Imaging Using Quantum Well Infrared Photodetector Arrays Invited Speaker: Quantum well infrared photodetector (QWIP) technology has opened up new opportunities to realize focal plane arrays (FPA) for high-performance thermal imaging [1]. High thermal and spatial resolution, low 1/f noise, low fixed-pattern noise, and high pixel operability makes QWIP FPAs appropriate for many applications. Due to their narrow absorption bands with relative spectral widths $\Delta \lambda $/$\lambda $ of the order of 10{\%}, QWIPs are particularly suitable for thermal imaging applications involving several atmospheric transmission bands or several colors within the same band. For dual-band/dual-color FPAs, QWIP technology has the unique property that the active region for the long-wavelength band is transparent for the short-wavelength band. In this talk, I will report on typical QWIP structures optimized for thermal imaging applications and on the performance of some state-of-the-art QWIP cameras which were jointly realized by the Fraunhofer-Institute for Applied Solid State Physics (Freiburg, Germany) and AIM Infrarot-Module GmbH (Heilbronn, Germany). Besides imagers for the 8 -- 12 $\mu $m long-wavelength infrared (LWIR) and 3 -- 5 $\mu $m mid-wavelength infrared (MWIR) regimes, these include a LWIR/MWIR dual-band QWIP FPA with 384x288 pixels which, at 6.8 ms integration time, exhibits a noise-equivalent temperature difference as low as 20.6~mK in the LWIR and 26.7~mK in the MWIR spectral bands. A specially designed diffraction grating is used for optical coupling of both spectral regimes. The array, which is based on a photoconductive QWIP for the MWIR and a photovoltaic ``low-noise'' QWIP for the LWIR, allows for synchronous and pixel-registered image acquisition in both bands. This functionality yields several advantages, including better distinction between target and background clutter, operation in a much wider range of ambient conditions, and the ability of remote absolute temperature measurement. \newline \newline [1] H. Schneider and H. C. Liu, \textit{Quantum Well Infrared Photodetectors: Physics and Applications}, ISBN 3540363238, Springer Series in Optical Sciences Vol. 126, 2006. [Preview Abstract] |
Friday, March 9, 2007 8:36AM - 8:48AM |
X39.00002: Detection of 3.4 THz Radiation from a Quantum Cascade Laser using Microbolometer Infrared Camera Barry Behnken, Gamani Karunasiri, Michele Lowe, Danielle Chamberlin, Peter Robrish, J. Faist Microbolometer infrared cameras are traditionally used for imaging objects in the 8-12 $\mu$m atmospheric window. Their use for imaging in the terahertz frequencies (0.1 -- 10 THz) is relatively unknown. In a recent experiment, a microbolometer camera with 160x120 pixels was used for real time detection of 3.4 THz radiation from a quantum cascade laser. The focal plane array of the camera consists of 50x50 $\mu$m$^{2}$ pixels made of a composite film of Si$_{3}$N$_{4}$ membrane and VO$_{x}$ thin resistive layer for sensing the temperature change. The laser was operated at 20 K with a peak power of 10 mW and duty cycle of 7{\%}, providing an average power of roughly 700 $\mu$W. Initial experiments were carried out without the focusing Ge lens of the camera, since the antireflection coating on it was found to absorb most of the THz laser power. Recently we have incorporated a picarin lens, capable of 80{\%} transmittance at THz frequencies, to enhance the light collection and improve detection capability. Video recordings of the laser beam interacting with various objects, with and without the use of focusing optics, will be presented. [Preview Abstract] |
Friday, March 9, 2007 8:48AM - 9:00AM |
X39.00003: Terahertz ellipsometry using electron-beam based sources T. Hofmann, U. Schade, M. Mross, T. Iowell, M. Schubert Spectroscopic ellipsometry is known as a viable and precise technique for the investigation of optical material properties in the far-infrared to the VUV spectral region. Generalized ellipsometry in the THz frequency domain allows in combination with strong magnetic fields at low temperatures investigation of low energy electron dynamics in semi- and superconducting materials. We report here on the first successful application of this technique to investigate condensed matter samples in the frequency range from 0.7 to 8 THz using a high-brilliance Terahertz synchrotron radiation source and a Smith-Purcell-effect Terahertz radiation source. We discuss and present THz range physical material properties due to bound and unbound charge resonances in low-dimensional semi- and superconducting materials. This research will provide understanding of optical properties for novel materials, inspire new designs, and accelerate development of optical Terahertz devices. [Preview Abstract] |
Friday, March 9, 2007 9:00AM - 9:12AM |
X39.00004: III-V semiconductor based infrared detectors and focal plane arrays David Z.-Y. Ting, S. V. Bandara, C. J. Hill, S. D. Gunapala, J. K. Liu, J. M. Mumolo, S. A. Keo, E. R. Blazejewski, Y.-C. Chang, S. B. Rafol We report recent results in III-V semiconductor based infrared detectors, including quantum well infrared photodetector (QWIP) based simultaneous dual-band infrared focal plane array, quantum dot infrared photodetector (QDIP) based large-format long wavelength infrared focal plane array, and development in far infrared photodetectors. [Preview Abstract] |
Friday, March 9, 2007 9:12AM - 9:24AM |
X39.00005: Development of GaAs blocked-impurity-band detectors for the far-infrared Lothar A. Reichertz, Jeffrey W. Beeman, Reinhard Katterloher, Nancy M. Haegel, Eugene E. Haller The far-infrared (or THz) region of the electromagnetic spectrum requires improved photon detectors, especially for large array formats for highly sensitive imaging in astronomy. For wavelengths greater than 120 $\mu$m stressed Ge photoconductors are currently being used with a cut off at 210 $\mu$m. GaAs is a promising material to overcome this limitation due to its lower donor binding energy. The problem of high dark currents in GaAs can be solved by using a multilayered blocked-impurity-band (BIB) detector concept. This allows for a more heavily doped infrared active layer which enables a thinner device and a further extension of the long wavelength cut off. Such a planar structure allows lithographic processes for much larger array formats than currently possible in stressed Ge technology. Although BIB technology is well established in Si, its transfer to other materials has proven difficult. Only recently is GaAs approaching the needed levels of purity and interface control. We have demonstrated spectral response in a multi layer GaAs BIB structure extending to 500 $\mu$m, using material grown through vapor phase epitaxial techniques. The test structures were grown on 4 inch wafers, demonstrating feasibility for a 32 x 32 (and ultimately larger) array. [Preview Abstract] |
Friday, March 9, 2007 9:24AM - 9:36AM |
X39.00006: The Study of Temperature Dependence and High Temperature Operation of Photoresponse in Superlattice Infrared Photodetectors Shih-Hung Lin, J.H. Lu, C.H. Kuan, J.Y. Feng, T.S. Lay For temperature dependence of photoresponse in superlattice with a single barrier, we have compared two samples' performance and concluded four factors are in effect including doping density in superlattice, externally applied bias, the single barrier's thickness and energy height. Doping density and temperature will change electron distribution in the first miniband of superlattice, and thereby the photoresponse. Scattering during the transport through barrier is increased with applied bias. Barrier thickness and height influence ballistic transport behavior and tunneling mechanism, respectively. Based on these factors, we design a structure of superlattice integrated with quantum wells to demonstrate photoresponse under high-temperature operation. By understanding those factors' effect, it is advantageous to design SLIPs for high-$T$ applications. [Preview Abstract] |
Friday, March 9, 2007 9:36AM - 9:48AM |
X39.00007: Effect of the Inclusion of Magnetically Active Imbedded Nanocomposites (MAINs) on the Absorption and Response of Infrared Detectors Gamini Ariyawansa, V.M. Apalkov, N. Dietz, S.G. Matsik, A.G.U. Perera The performance of heterojunction infrared detectors can be improved by MAINs in the emitter layer which use free carrier absorption. As the free carrier absorption requires a phonon or similar particle to conserve momentum, the additional disorder introduced by the MAINs increases absorption, leading to improved response. As the GaMnN MAINs show ferromagnetic behavior, the application of a magnetic field can lead to further response increases. Calculations will be presented on the effect of the size and density of the GaMnN MAINs on the expected absorption and response for Tunable Magnetically Active Imbedded Nanocomposite InfraRed (TMAINIR) sensors in the LWIR and THz ranges. The addition of 10 nm diameter GaMaN MAINs with a density of $10^{11}$ cm$^{-2}$ will lead to an increase in the calculated peak response from 15 to 75 mA while also shifting the peak wavelength from 8 to 6 $\mu$m for a design with a threshold of 15 $\mu$m. Applying an electric field can further increase the peak response up to $\sim 85$ $\mu$m. Results will be presented on the effect of the GaMnN MAINs on the expected absorption and response for detector designs in the LWIR and THz ranges. [Preview Abstract] |
Friday, March 9, 2007 9:48AM - 10:00AM |
X39.00008: A new mechanism for THz-frequency radiation generation: Nonlinear strain waves in piezoelectrics Evan Reed, Michael Armstrong Using molecular dynamics simulations and analytics, we show that extremely large strain amplitude THz frequency acoustic waves can spontaneously form in crystalline GaN at the front of a shock wave and generate THz frequency radiation at an interface with AlN or another piezoelectric material. This new mechanism for the generation of THz radiation can be realized using a table-top ultrafast laser and has fundamentally different limiting properties than existing nonlinear optical ultrafast techniques for THz generation. [Preview Abstract] |
Friday, March 9, 2007 10:00AM - 10:12AM |
X39.00009: Electronically Tunable Grating-Gate Terahertz Detectors E.A. Shaner, M.C. Wanke, Mark Lee, A.D. Grine, J.L. Reno, S.J. Allen Spectroscopy in the millimeter-wave to THz frequencies has received a great deal of recent interest for security applications and chemical identification. This talk will address detectors that utilize plasmons in high-mobility GaAs/AlGaAs quantum well structures to provide a frequency tunable detector response. In particular, recent advances on the grating-gate detector, including membrane and split-gate versions, will be presented. The discussion will include our understanding of the detection mechanisms involved as well as the noise equivalent powers that have been achieved in the various geometries. Currently, the grating-gate style of detector covers a frequency range from 150GHz to 1THz at temperatures ranging from 4K to 80K, however, the ultimate frequency and temperature limits of these detectors are not currently known. The ability to tune the detector response by simply changing a gate voltage leads to an attractive `spectrometer-on-a-chip' where no moving parts would be needed for THz spectral analysis. To date we have achieved spectral scans from 600GHz to 1THz in 12.5ms with a measured 15GHz minimum linewidth. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Friday, March 9, 2007 10:12AM - 10:24AM |
X39.00010: Brewster angle phenomenon in two-dimensional metallic photonic crystals and its application to polarization beam splitting Xinhua Hu, Kai-Ming Ho The authors show the Brewster angle phenomenon of p waves in two-dimensional metallic photonic crystals of rectangular lattices with effective medium theory and accurate multiple-scattering calculations. The Brewster angle can be tuned over a wide range by varying the structure parameters. Based on this phenomenon, the authors propose a polarization beam splitter which can completely separate the p and s waves at an incident angle of 45$^{\circ}$ $\pm$ 10$^{\circ}$ in a very wide wavelength range (1$\sim$500 micron). [Preview Abstract] |
Friday, March 9, 2007 10:24AM - 10:36AM |
X39.00011: Dynamics of 980 nm VCSELs Characterized Using Temperature Dependent RIN Spectra Rashid Safaisini, Ahmad N. Al-Omari, John R. Joseph, Kevin L. Lear High speed optical interconnects are replacing copper connections in ever shorter link distance, low cost, high speed communication systems employing directly modulated laser diodes. In very short distance systems ($<$1 m), laser diode bandwidth is a major limitation. Laser intensity noise spectra contain valuable information on laser dynamics including resonant frequency and damping. In this work, vertical cavity surface emitting lasers (VCSELs) are fabricated from a metal-organic chemical vapor deposition (MOCVD) grown AlGaAs structure on an n-type substrate. The intrinsic resonance frequency and damping constant of 980 nm VCSELs are measured. Two methods are used: constant temperature and varying injection current and constant injection current with varying temperature. After fitting the spectra to the conventional damped oscillator model to extract resonance frequency and damping, K-factor analysis is performed both on the conventional constant temperature data as well as the constant current data. The results of the two approaches are compared. [Preview Abstract] |
Friday, March 9, 2007 10:36AM - 10:48AM |
X39.00012: Detection of Nanomechanical Device Motion by Spatiotemporal Stroboscopic Interferometry Joseph Losby, F. Giesen, J. Moroz, A. Fraser, M. Belov, G. McKinnon, Y. Ning, W. Hiebert, M.R. Freeman Actuation and detection of nanomechanical device motion in the ultrahigh frequency regime remains a considerable challenge. We have performed broadband characterization of the displacement of silicon NEMS cantilevers and doubly-clamped beams by stroboscopic optical interferometric detection synchronized to pulsed electrostatic actuation. Initial test structures have yielded time-domain measurements of the response of structures having fundamental resonant frequencies up to 580 MHz. Calibration of the vertical displacement sensitivity and imaging of out-of-plane flexural modes will also be discussed. This study aims to extend the potential of interferometry for research on nanomechanical systems. [Preview Abstract] |
Friday, March 9, 2007 10:48AM - 11:00AM |
X39.00013: Terahertz imaging using the Jefferson Lab -- FEL high power broadband terahertz source J. Michael Klopf, Matthew Coppinger, Nathan Sustersic, James Kolodzey, Gwyn P. Williams Imaging using THz radiation is of considerable interest due to the non-ionizing nature of the radiation as well as the relative transmission, absorption, and reflection of various materials of interest. With a source of sufficient power and spectral characteristics, it is possible to realize imaging capabilities that were not previously possible. At the Jefferson Lab -- Free Electron Laser Facility, a high power broadband source has been commissioned, providing an ideal resource for the development of THz imaging technology. Even with this high power source now available, significant challenges remain in creating detector arrays with sufficient responsivity and creating optical systems to provide the illumination and resolution necessary to create usable images. In collaboration with a group from the University of Delaware, unprecedented imaging tests have been performed toward this goal and are presented here. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700