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Page 1 (5 Items)
| 1. | Minority electron unipolar photodetectors based on type II InAs/GaSb/AlSb superlattices for very long wavelength infrared detection
B.M. Nguyen, S. Bogdanov, S. Abdollahi Pour, and M. Razeghi
Applied Physics Letters, Vol. 95, No. 18, p. 183502-- November 2, 2009
We present a hybrid photodetector design that inherits the advantages of traditional photoconductive and photovoltaic devices. The structure consists of a barrier layer blocking the transport of majority holes in a p-type semiconductor, resulting in an electrical transport due to minority carriers with low current density. By using the M-structure superlattice as a barrier region, the band alignments can be experimentally controlled, allowing for the efficient extraction of the photosignal with less than 50 mV bias. At 77 K, a 14 µm cutoff detector exhibits a dark current 3.3 mA/cm(2), a photoresponsivity of 1.4 A/W, and the associated shot noise detectivity of 4×10(10) Jones. ©2009 American Institute of Physics ...[Visit Journal]
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| 2. | Demonstration of high performance long wavelength infrared type II InAs/GaSb superlattice photodidoe grown on GaAs substrate
S. Abdollahi Pour, B.M. Nguyen, S. Bogdanov, E.K. Huang, and M. Razeghi
Applied Physics Letters, Vol. 95, No. 17, p. 173505-- October 26, 2009
We report the growth and characterization of long wavelength infrared type-II InAs/GaSb superlattice photodiodes with a 50% cut-off wavelength at 11 µm, on GaAs substrate. Despite a 7.3% lattice mismatch to the substrate, photodiodes passivated with polyimide exhibit an R0A value of 35 Omega cm2 at 77 K, which is in the same order of magnitude as reference devices grown on native GaSb substrate. With a reverse applied bias less than 500 mV, the dark current density and differential resistance-area product are close to that of devices on GaSb substrate, within the tolerance of the processing and measurement. The quantum efficiency attains the expected value of 20% at zero bias, resulting in a Johnson limited detectivity of 1.1×10(11) Jones. Although some difference in performances is observed, devices grown on GaAs substrate already attained the background limit performance at 77 K with a 300 K background and a 2pi field of view. ©2009 American Institute of Physics ...[Visit Journal]
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| 3. | Quantum dot in a well infrared photodetectors for high operating temperature focal plane arrays
S. Tsao, T. Yamanaka, S. Abdollahi Pour, I-K Park, B. Movaghar and M. Eazeghi
SPIE Proceedings, San Jose, CA Volume 7234-0V-- January 25, 2009
InAs quantum dots embedded in InGaAs quantum wells with InAlAs barriers on InP substrate grown by metalorganic chemical vapor deposition are utilized for high operating temperature detectors and focal plane arrays in the middle wavelength infrared. This dot-well combination is unique because the small band offset between the InAs dots and the InGaAs well leads to weak dot confinement of carriers. As a result, the device behavior differs significantly from that in the more common dot systems that have stronger confinement. Here, we present energy level modeling of our QD-QW system and apply these results to interpret the detector behavior. Detectors showed high performance with D* over 1010 cm·Hz1/2W-1 at 150 K operating temperature and with high quantum efficiency over 50%. Focal plane arrays have been demonstrated operating at high temperature due to the low dark current observed in these devices. ...[Visit Journal]
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| 4. | Gain and recombination dynamics in photodetectors made with quantum nanostructures: the quantum dot in a well and the quantum well
B. Movaghar, S. Tsao, S. Abdollahi Pour, T. Yamanaka, and M. Razeghi
Virtual Journal of Nanoscale Science & Technology, Vol. 18, No. 14-- October 6, 2008 ...[Visit Journal]
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| 5. | Gain and recombination dynamics in photodetectors made with quantum nanostructures: The quantum dot in a well and the quantum well
B. Movaghar, S. Tsao, S. Abdollahi Pour, T. Yamanaka, and M. Razeghi
Physical Review B, Vol. 78, No. 11-- September 15, 2008
We consider the problem of charge transport and recombination in semiconductor quantum well infrared photodetectors and quantum-dot-in-a-well infrared detectors. The photoexcited carrier relaxation is calculated using rigorous random-walk and diffusion methods, which take into account the finiteness of recombination cross sections, and if necessary the memory of the carrier generation point. In the present application, bias fields are high and it is sufficient to consider the drift limited regime. The photoconductive gain is discussed in a quantum-mechanical language, making it more transparent, especially with regard to understanding the bias and temperature dependence. Comparing experiment and theory, we can estimate the respective recombination times. The method developed here applies equally well to nanopillar structures, provided account is taken of changes in mobility and trapping. Finally, we also derive formulas for the photocurrent time decays, which in a clean system at high bias are sums of two exponentials. ...[Visit Journal]
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