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IEEE Photonics Technology Letters 01/2012; 24(18):1581-1583. · 2.19 Impact Factor
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David Z-Y Ting,
Alexander Soibel,
Cory J Hill,
Jean Nguyen,
Sam A Keo,
Sir B Rafol,
Baohua Yang,
Mike C Lee,
Jason M Mumolo,
John K Liu,
Linda Hoeglund,
Sarath D Gunapala
Infrared Physics & Technology 05/2011; 54(3):267-272. · 1.30 Impact Factor
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01/2011: pages 1-57; , ISBN: 9780123813374 · 2.33 Impact Factor
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ABSTRACT: Surface leakage reduction has been achieved using BCl3/Cl2/CH4/H2/Ar inductively coupled plasma dry etching for pixel isolation of high performance long-wave infrared superlattice detectors. The leakage has been minimized by effectively increasing the surface resistivity by more than 7.4 times and decreasing the surface state density by more than 3.8 times. Through altering the etch mechanism, the dark current density was reduced by more than two orders of magnitude where a dark current of 1.01×10−5 A/cm2 at 200 mV was achieved at T = 77 K for a 10.3 μm detector with a peak quantum efficiency value of 30% (without antireflection coating).
Applied Physics Letters 08/2010; 97(5):051108-051108-3. · 3.84 Impact Factor
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ABSTRACT: We experimentally investigate the noise and gain of high-performance long-wavelength superlattice (SL) infrared photodetectors. We compare a recently demonstrated SL heterodiode, which exhibits an electrical gain much larger than unity, with a SL photodetector without gain to show that the electrical gain in these devices originates from the device structure rather than from the SL absorber. We directly measure the noise spectra of a high performance SL, and show that 1/f noise is not intrinsically present in these structures. However, we find that a very large extraneous frequency-dependent noise can be generated by side-wall leakage currents. Analysis of the noise and gain indicate that the exact dependence of the shot noise on the dark current in these SL heterodiodes can be different from that in the diffusion-limited diode homojunction.
Applied Physics Letters 03/2010; 96(11):111102-111102-3. · 3.84 Impact Factor
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ABSTRACT: We describe a long wavelength infrared detector where an InAs/GaSb superlattice absorber is surrounded by a pair of electron-blocking and hole-blocking unipolar barriers. A 9.9 μm cutoff device without antireflection coating based on this complementary barrier infrared detector design exhibits a responsivity of 1.5 A/W and a dark current density of 0.99×10−5 A/cm2 at 77 K under 0.2 V bias. The detector reaches 300 K background limited infrared photodetection (BLIP) operation at 87 K, with a black-body BLIP D∗ value of 1.1×1011 cm Hz1/2/W for f/2 optics under 0.2 V bias.
Applied Physics Letters 07/2009; 95(2):023508-023508-3. · 3.84 Impact Factor
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David Z.-Y. Ting,
Sumith V. Bandara,
Cory J. Hill,
Sarath D. Gunapala,
Yia-Chung Chang,
H. C. Liu,
C. Y. Song,
Alexander Soibel,
Jason Mumolo,
Jean Nguyen,
John K. Liu,
Sam A. Keo,
Sir B. Rafol,
E. R. Blazejewski
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ABSTRACT: We report work on several quantum structure based infrared detectors. We describe the concept and experimental progress of the quantum well intra-subband photodetector (QWISP), which is closely related to the quantum-well infrared photodetector (QWIP), but uses the dopant-assisted intra-subband absorption mechanism in quantum wells for normal-incidence far infrared/terahertz radiation detection. We describe the concept of the submonolayer quantum dot infrared photodetector (SML QDIP), and report experimental device results on long-wavelength infrared detection, and imaging results from a mega-pixel focal plane arrays, which produced clear infrared images up to 80K. We discuss how superlattice heterostructures, particularly those using unipolar barriers, can offer significant performance advantages over homojunction superlattices in infrared detection. We also summary recent device results on a superlattice heterostructure based barrier infrared detectors (BIRDs).© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
04/2009;
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ABSTRACT: We describe the concept of the submonolayer quantum dot infrared photodetector (SML QDIP) and report experimental device results on long-wavelength infrared detection. An SML QDIP structure was fabricated into megapixel focal plane arrays, which produced clear infrared images up to 80 K. Detectors in the focal plane showed a responsivity peak at 7.8 μ m and noise equivalent temperature difference of 33 mK at 70 K.
Applied Physics Letters 04/2009; · 3.84 Impact Factor
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ABSTRACT: We describe a recently proposed device concept of using of the dopant-assisted intra-subband absorption mechanism in quantum wells for normal-incidence far infrared / terahertz radiation detection. The Quantum Well Intra-Subband Photodetector (QWISP) is closely related to the quantum-well infrared photodetector (QWIP), which is now been utilized routinely to fabricate large-format (mega-pixel), multi-spectral (3 to 15 μm) focal plane arrays. The QWISP is a compact device that is compatible with existing GaAs QWIP focal-plane array technology. We describe the basic physics and device concept of the QWISP, present a theoretical analysis on its far-IR detection properties, and discuss prospects toward its experimental realization.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
04/2008;
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ABSTRACT: The authors present a theoretical analysis on the possibility of using the dopant-assisted intrasubband absorption mechanism in quantum wells for normal-incidence far infrared/terahertz radiation detection. The authors describe the proposed concept of the quantum well intrasubband photodetector (QWISP), which is a compact semiconductor heterostructure device compatible with existing GaAs focal-plane array technology, and present theoretical results demonstrating strong normal-incidence absorption and responsivity in the QWISP.
Applied Physics Letters 09/2007; · 3.84 Impact Factor
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ABSTRACT: We propose a mechanism for achieving bidirectional spin pumping in conventional nonmagnetic semiconductor resonant tunneling heterostructures under zero magnetic field. The device is designed specifically to take advantage of the special spin configuration described by the Rashba effect in asymmetric quantum wells. It induces the simultaneous flow of oppositely spin-polarized current components in opposite directions through spin-dependent resonant tunneling, and can thus generate significant levels of spin current with very little net electrical current across the tunnel structure, a condition characterized by a greater-than-unity current spin polarization. We also present modeling results on temperature dependence and finite device size effects. © 2003 American Institute of Physics.
Applied Physics Letters 09/2003; · 3.84 Impact Factor
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ABSTRACT: We propose an InAs/GaSb/AlSb-based asymmetric resonant interband tunneling diode as a spin filter. The interband design exploits large valence band spin–orbit interaction to provide strong spin selectivity, without suffering from fast hole spin relaxation. Spin filtering efficiency is also enhanced by the reduction of tunneling through quasibound states near the zone center, where spin spitting vanishes and spin selectivity is difficult. Our calculations show that, when coupled with an emitter or collector capable of lateral momentum selectivity, the asymmetric resonant interband tunneling diode can achieve significant spin filtering in conventional nonmagnetic semiconductor heterostructures under zero magnetic field. © 2002 American Institute of Physics.
Applied Physics Letters 12/2002; · 3.84 Impact Factor
