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Page 1 (18 Items)
| 1. | 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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| 2. | Demonstration of mid-infrared type-II InAs/GaSb superlattice photodiodes grown on GaAs substrate
B.M. Nguyen, D. Hoffman, E.K. Huang, S. Bogdanov, P.Y. Delaunay, M. Razeghi and M.Z. Tidrow
Applied Physics Letters, Vol. 94, No. 22-- June 8, 2009
We report the growth and characterization of type-II InAs/GaSb superlattice photodiodes grown on
a GaAs substrate. Through a low nucleation temperature and a reduced growth rate, a smooth GaSb
surface was obtained on the GaAs substrate with clear atomic steps and low roughness morphology.
On the top of the GaSb buffer, a p+-i-n+ type-II InAs/GaSb superlattice photodiode was grown with
a designed cutoff wavelength of 4 μm. The detector exhibited a differential resistance at zero bias (R0A)in excess of 1600 Ω·cm2 and a quantum efficiency of 36.4% at 77 K, providing a specific detectivity of 6 X 1011 cm·Hz½/W and a background limited operating temperature of 100 K with a 300 K background. Uncooled detectors showed similar performance to those grown on GaSb
substrates with a carrier lifetime of 110 ns and a detectivity of 6 X 108 cm·Hz½/W. ...[Visit Journal]
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| 3. | Recent Advances in LWIR Type-II InAs/GaSb Superlattice Photodetectors and Focal Plane Arrays at the Center for Quantum Devices
M. Razeghi, D. Hoffman, B.M. Nguyen, P.Y. Delaunay, E.K. Huang, M.Z. Tidrow, and V. Nathan
Proceedings of the IEEE, Vol. 97, No. 6, p. 1056-1066-- June 1, 2009
In recent years, Type-II InAs/GaSb superlattice photo-detectors have experienced significant improvements in material quality, structural designs, and imaging applications. They now appear to be a possible alternative to the state-of-the-art HgCdTe (MCT) technology in the long and very long wavelength infrared regimes. At the Center for Quantum Devices, we have successfully realized very high quantum efficiency, very high dynamic differential resistance R0A - product LWIR Type – II InAs/GaSb superlattice photodiodes with efficient surface passivation techniques. The demonstration of high quality LWIR Focal Plane Arrays that were 100 % fabricated in - house reaffirms the pioneer position of this university-based laboratory. ...[Visit Journal]
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| 4. | High performance antimony based type-II superlattice photodiodes on GaAs substrates
B.M. Nguyen, D. Hoffman, E.K. Huang, P.Y. Delaunay, and M. Razeghi
SPIE Porceedings, Vol. 7298, Orlando, FL 2009, p. 72981T-- April 13, 2009
In recent years, Type II InAs/GaSb superlattices grown on GaSb substrate have achieved significant
advances in both structural design and material growth, making Type II superlattice infrared detector a rival competitor to the state-of-the-art MCT technology. However, the limited size and strong
infrared absorption of GaSb substrates prevent large format type-II superlattice infrared imagers from
being realized. In this work, we demonstrate type-II superlattices grown on GaAs substrates, which is a significant step toward third generation infrared imaging at low cost. The device performances of Type II superalttice photodetectors grown on these two substrates are compared. ...[Visit Journal]
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| 5. | Surface leakage reduction in narrow band gap type-II antimonide-based superlattice photodiodes
E.K. Huang, D. Hoffman, B.M. Nguyen, P.Y. Delaunay and M. Razeghi
Applied Physics Letters, Vol. 94, No. 5, p. 053506-1-- February 2, 2009
Inductively coupled plasma (ICP) dry etching rendered structural and electrical enhancements on type-II antimonide-based superlattices compared to those delineated by electron cyclotron resonance (ECR) with a regenerative chemical wet etch. The surface resistivity of 4×105 Omega cm is evidence of the surface quality achieved with ICP etching and polyimide passivation. By only modifying the etching technique in the fabrication steps, the ICP-etched devices with a 9.3 µm cutoff wavelength revealed a diffusion-limited dark current density of 4.1×10−6 A/cm2 and a maximum differential resistance at zero bias in excess of 5300 Ω·cm2 at 77 K, which are an order of magnitude better in comparison to the ECR-etched devices. ...[Visit Journal]
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| 6. | Background limited performance of long wavelength infrared focal plane arrays fabricated from M-structure InAs-GaSb superlattices
P.Y. Delaunay, B.M. Nguyen, D. Hoffman, E.K. Huang, and M. Razeghi
IEEE Journal of Quantum Electronics, Vol. 45, No. 2, p. 157-162.-- February 1, 2009
The recent introduction of a M-structure design improved both the dark current and R0A performances of Type-II InAs-GaSb photodiodes. A focal plane array fabricated with this design was characterized at 81 K. The dark current of individual pixels was measured between 1.1 and 1.6 nA, 7 times lower than previous superlattice FPAs. This led to a higher dynamic range and longer integration times. The quantum efficiency of detectors without antireflective coating was 74%. The noise equivalent temperature difference reached 23 mK, limited only by the performance of the testing system and the read out integrated circuit. Background limited performances were demonstrated at 81 K for a 300 K background. ...[Visit Journal]
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| 7. | The importance of band alignment in VLWIR type-II InAs/GaSb heterodiodes containing the M-structure barrier
D. Hoffman, B.M. Nguyen, E.K. Huang, P.Y. Delaunay, S. Bogdanov, P. Manukar, M. Razeghi, and V. Nathan
SPIE Proceedings, San Jose, CA Volume 7222-15-- January 26, 2009
The Type-II InAs/GaSb superlattice photon detector is an attractive alternative to HgCdTe photodiodes and QWIPS. The use of p+ - pi - M - N+ heterodiode allows for greater flexibility in enhancing the device performance. The utilization of the Empirical Tight Binding method gives the band structure of the InAs/GaSb superlattice and the new M- structure (InAs/GaSb/AlSb/GaSb) superlattice allowing for the band alignment between the binary superlattice and the M- superlattice to be determined and see how it affects the optical performance. Then by modifying the doping level of the M- superlattice an optimal level can be determined to achieve high detectivity, by simultaneously improving both photo-response and reducing dark current for devices with cutoffs greater than 14.5 µm. ...[Visit Journal]
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| 8. | Background limited performance of long wavelength infrared focal plane arrays fabricated from M-structure InAs/GaSb superlattices
P.Y. Delaunay, B.M. Nguyen, D. Hoffman, E.K. Huang, P. Manurkar, S. Bogdanov and M. Razeghi
SPIE Proceedings, San Jose, CA Volume 7222-0W-- January 26, 2009
Recent advances in the design and fabrication of Type-II InAs/GaSb superlattices allowed the realization of high performance long wavelength infrared focal plane arrays. The introduction of an Mstructure barrier between the n-type contact and the pi active region reduced the tunneling component of the dark current. The M-structure design improved the noise performance and the dynamic range of FPAs at low temperatures. At 81K, the NEDT of the focal plane array was 23 mK. The noise of the camera was dominated by the noise component due to the read out integrated circuit. At 8 µm, the median quantum efficiency of the detectors was 71%, mainly limited by the reflections on the backside of the array.
...[Visit Journal]
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| 9. | Inductively coupled plasma etching and processing techniques for type-II InAs/GaSb superlattices infrared detectors toward high fill factor focal plane arrays
E.K. Huang, B.M. Nguyen, D. Hoffman, P.Y. Delaunay and M. Razeghi
SPIE Proceedings, San Jose, CA Volume 7222-0Z-- January 26, 2009
A challenge for Type-II InAs/GaSb superlattice (T2SL) photodetectors is to achieve high fill factor, high aspect ratio etching for third generation focal plane arrays (FPAs). Initially, we compare the morphological and electrical results of single element T2SL photodiodes after BCl3/Ar inductively coupled plasma (ICP) and electron cyclotron resonance (ECR) dry etching. Using a Si3N4 hard mask, ICP-etched structures exemplify greater sidewall verticality and smoothness, which are essential toward the realization of high fill factor FPAs. ICP-etched single element devices with SiO2 passivation that are 9.3 µm in cutoff wavelength achieved vertical sidewalls of 7.7 µm in depth with a resistance area product at zero bias of greater than 1,000 Ω·cm2 and maximum differential resistance in excess of 10,000 Ω·cm2 at 77 K. By only modifying the etching technique in the fabrication steps, the ICP-etched photodiodes showed an order of magnitude decrease in their dark current densities in comparison to the ECR-etched devices. Finally, high aspect ratio etching is demonstrated on mutli-element arrays with 3 µm-wide trenches that are 11 µm deep. ...[Visit Journal]
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| 10. | Band edge tunability of M-structure for heterojunction design in Sb based type II superlattice photodiodes
B.M. Nguyen, D. Hoffman, P.Y. Delaunay, E.K. Huang, M. Razeghi, and J. Pellegrino
Applied Physics Letters, Vol. 93, No. 16, p. 163502-1-- October 20, 2008
We present theoretically and experimentally the effect of the band discontinuity in type II misaligned InAs/GaSb superlattice heterodiodes. Calculations using the empirical tight binding method have shown the great flexibility in tuning the energy levels of the band edge in M-structure superlattice as compared to the standard InAs/GaSb superlattice. Through the experimental realization of several p-pi-M-n photodiodes, the band discontinuity alignment between the standard binary-binary superlattice and the M-structured superlattice was investigated via optical characterization. The agreement between the theoretical predictions and the experimental measurement confirms the capability of controlling the M-structure band edges and suggests a way to exploit this advantage for the realization of heterostructures containing an M-structured superlattice without bias dependent operation. ...[Visit Journal]
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| 11. | Background limited long wavelength infrared type-II InAs/GaSb superlattice photodiodes operating at 110 K
B.M. Nguyen, D. Hoffman, E.K. Huang, P.Y. Delaunay, and M. Razeghi
Applied Physics Letters, Vol. 93, No. 12, p. 123502-1-- September 22, 2008
The utilization of the P+-pi-M-N+ photodiode architecture in conjunction with a thick active region can significantly improve long wavelength infrared Type-II InAs/GaSb superlattice photodiodes. By studying the effect of the depletion region placement on the quantum efficiency in a thick structure, we achieved a topside illuminated quantum efficiency of 50% for an N-on-P diode at 8.0 µm at 77 K. Both the double heterostructure design and the application of polyimide passivation greatly reduce the surface leakage, giving an R0A of 416 Ω·cm2 for a 1% cutoff wavelength of 10.52 µm, a Shot–Johnson detectivity of 8.1×1011 cm·Hz½/W at 77 K, and a background limited operating temperature of 110 K with 300 K background. ...[Visit Journal]
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| 12. | Development of material quality and structural design for high performance type-II InAs/GaSb superlattice photodiodes and focal plane arrays
M. Razeghi, B.M. Nguyen, D. Hoffman, P.Y. Delaunay, E.K. Huang, M.Z. Tidrow and V. Nathan
SPIE Porceedings, Vol. 7082, San Diego, CA 2008, p. 708204-- August 11, 2008
Recent progress made in the structure design, growth and processing of Type-II InAs/GaSb
superlattice photo-detectors lifted both the quantum efficiency and the R0A product of the detectors. Type-II superlattice demonstrated its ability to perform imaging in the Mid-Wave Infrared (MWIR)and Long-Wave Infrared (LWIR) ranges, becoming a potential competitor for technologies such as Quantum Well Infrared Photo-detectors (QWIP) and Mercury Cadmium Telluride (MCT). Using an
empirical tight-binding model, we developed superlattices designs that were nearly lattice-matched to the GaSb substrates and presented cutoff wavelengths of 5 and 11 μm. We demonstrated high quality material growth with X-ray FWHM below 30 arcsec and an AFM rms roughness of 1.5 Å over an
area of 20x20 μm2. The detectors with a 5 μm cutoff, capable of operating at room temperature,
showed a R0A of 1.25 106 Ω.cm2 at 77K, and a quantum efficiency of 32%. In the long wavelength
infrared, we demonstrated high quantum efficiencies above 50% with high R0A products of 12 Ω.cm2
by increasing the thickness of the active region. Using the novel M-structure superlattice design, more than one order of magnitude improvement has been observed for electrical performance of the
devices. Focal plane arrays in the middle and long infrared range, hybridized to an Indigo read out
integrated circuit, exhibited high quality imaging. ...[Visit Journal]
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| 13. | Very high performance LWIR and VLWIR type-II InAs/GaSb superlattice photodiodes with M-structure barrier
B.M. Nguyen, D. Hoffman, P.Y. Delaunay, E.K. Huang and M. Razeghi
SPIE Porceedings, Vol. 7082, San Diego, CA 2008, p. 708205-- August 11, 2008
LWIR and VLWIR type II InAs/GaSb superlattice photodetectors have for long time suffered from a
high dark current level and a low dynamic resistance which hampers the its emergence to the infrared detection and imaging industry. However, with the use of M-structure superlattice, a new type II binary InAs/GaSb/AlSb superlattice design, as an effective blocking barrier, the dark current in type II superlattice diode has been significantly reduced. We have obtained comparable differential resistance product to the MCT technology at the cut-off wavelength of 10 and 14μm. Also, this new design is compatible with the optical optimization scheme, leading to high quantum efficiency, high special detectivity devices for photon detectors and focal plane arrays. ...[Visit Journal]
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| 14. | The effect of doping the M-barrier in very long-wave type-II InAs/GaSb heterodiodes
D. Hoffman, B.M. Nguyen, E.K. Huang, P.Y. Delaunay, M. Razeghi, M.Z. Tidrow and J. Pellegrino
Applied Physics Letters, Vol. 93, No. 3, p. 031107-1-- July 21, 2008
A variation on the standard homo-diode Type-II superlattice with an M-barrier between the pi-region and the n-region is shown to suppress the dark currents. By determining the optimal doping level of the M-superlattice, dark current densities of 4.95 mA·cm-2 and quantum efficiencies in excess of 20% have been demonstrated at the moderate reverse bias of 50 mV; allowing for near background-limited performance with a Johnson-noise detectivity of 3.11×1010 Jones at 77 K for a 14.58 µm cutoff wavelength for large area diodes without passivation. This is comparable to values for the state-of-the-art HgCdTe photodiodes. ...[Visit Journal]
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| 15. | High quantum efficiency two color type-II InAs/GaSb n-i-p-p-i-n photodiodes
P.Y. Delaunay, B.M. Nguyen, D. Hoffman, A. Hood, E.K. Huang, M. Razeghi, and M.Z. Tidrow
Applied Physics Letters, Vol. 92, No. 11, p. 111112-1-- March 17, 2008
A n-i-p-p-i-n photodiode based on type-II InAs/GaSb superlattice was grown on a GaSb substrate. The two channels, with respective 50% of responsivity cutoff wavelengths at 7.7 and 10 µm, presented quantum efficiencies (QEs) of 47% and 39% at 77 K. The devices can be operated as two diodes for simultaneous detection or as a single n-i-p-p-i-n detector for sequential detection. In the latter configuration, the QEs at 5.3 and 8.5 µm were measured as high as 40% and 39% at 77 K. The optical cross-talk between the two channels could be reduced from 0.36 to 0.08 by applying a 50 mV bias.
...[Visit Journal]
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| 16. | Recent advances in LWIR type-II InAs/GaSb superlattice photodetectors and focal plane arrays at the Center for Quantum Devices
M. Razeghi, D. Hoffman, B.M. Nguyen, P.Y. Delaunay, E.K. Huang, and M.Z. Tidrow
SPIE Porceedings, Vol. 6940, Orlando, FL 2008, p. 694009-- March 17, 2008
In recent years, Type-II InAs/GaSb superlattice photo-detectors have experienced significant improvements in material quality, structural designs, and imaging applications. They now appear to be a possible alternative to the state-of-the-art
HgCdTe (MCT) technology in the long and very long wavelength infrared regimes. At the Center for Quantum Devices,we have successfully realized very high quantum efficiency, very high dynamic differential resistance R0A - product LWIR Type – II InAs/GaSb superlattice photodiodes with efficient surface passivation techniques. The demonstration of high quality LWIR Focal Plane Arrays that were 100 % fabricated in - house reaffirms the pioneer position of this university-based laboratory. ...[Visit Journal]
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| 17. | High-Power (~9um) Quantum Cascade Lasers
S. Slivken, Z. Huang, A. Evans, and M. Razeghi
Applied Physics Letters 80 (22)-- June 3, 2002
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| 18. | High-Power (~9 um) Quantum Cascade Lasers
S. Slivken, Z. Huang, A. Evans, and M. Razeghi
Virtual Journal of Nanoscale Science and Technology 5 (22)-- June 3, 2002 ...[Visit Journal]
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Page 1 (18 Items)
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