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Dive into the research topics where E. P. G. Smith is active.

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Featured researches published by E. P. G. Smith.


Applied Physics Letters | 2012

High operating temperature interband cascade midwave infrared detector based on type-II InAs/GaSb strained layer superlattice

Nutan Gautam; S. Myers; Ajit V. Barve; B. Klein; E. P. G. Smith; Dave. R. Rhiger; L. R. Dawson; S. Krishna

We report on an interband cascade mid-wave infrared (MWIR) detector based on type-II InAs/GaSb/AlSb strained layer superlattices (T2SL). The reported device has a seven-stage cascade region, each segment containing a MWIR absorber region, a graded T2SL transport region, and an interband tunneling region. Above room temperature spectral response was observed, with a cutoff wavelength of 7 μm at 420 K. Detailed radiometric measurements yielded a Johnson noise limited detectivity of 3.0 × 1011 cmHz1/2W−1 (8.9 × 108 cmHz1/2W−1) and a dark current density of 3.6 × 10−7 A/cm−2 (7.3 × 10−3 A/cm−2) near zero bias with a 100% cutoff wavelength of 5.2 μm and 6.2 μm at 77 K (295 K), respectively, with an estimated 36.2% QE.


Proceedings of SPIE, the International Society for Optical Engineering | 2005

Third Generation FPA Development Status at Raytheon Vision Systems

W. A. Radford; E. A. Patten; D. F. King; Gregory K. Pierce; J. Vodicka; P. M. Goetz; G. M. Venzor; E. P. G. Smith; R. W. Graham; S. M. Johnson; J. A. Roth; Brett Z. Nosho; J. E. Jensen

Raytheon Vision Systems (RVS) is developing two-color, large-format infrared FPAs to support the US Armys Third Generation FLIR systems. RVS has produced 640 x 480 two-color FPAs with a 20 micron pixel pitch. Work is also underway to demonstrate a 1280 x 720 two-color FPA in 2005. The FPA architecture has been designed to achieve nearly simultaneous temporal detection of the spectral bands while being producible for pixel dimensions as small as 20 microns. Raytheons approach employs a readout integrated circuit (ROIC) with Time Division Multiplexed Integration (TDMI). This ROIC is coupled to bias-selectable two-color detector array with a single contact per pixel. The two-color detector arrays are fabricated from MBE-grown HgCdTe triple layer heterojunction (TLHJ) wafers. The single indium bump design is producible for 20 μm unit cells and exploits mature fabrication processes that are in production at RVS for Second Generation FPAs. This combination allows for the high temporal and spatial color registration while providing a low-cost, highly producible and robust manufacturing process. High-quality MWIR/LWIR (M/L) 640 x 480 TDMI FPAs with have been produced and imaged from multiple fabrication lots. These FPAs have LWIR cutoffs ranging to 11 micron at 78K. These 20 micron pixel FPAs have demonstrated excellent sensitivity and pixel operabilities exceeding 99%. NETDs less than 25 mK at f/5 have been demonstrated for both bands operating simultaneously.


IEEE Journal of Quantum Electronics | 2013

Barrier Engineered Infrared Photodetectors Based on Type-II InAs/GaSb Strained Layer Superlattices

N. Gautam; S. Myers; Ajit V. Barve; B. Klein; E. P. G. Smith; Dave. R. Rhiger; Ha Sul Kim; Z.-B. Tian; Sanjay Krishna

We present the design, growth, fabrication, and characterization of unipolar barrier photodiodes, pBiBn, based on type-II InAs/GaSb superlattice for midwave and longwave infrared detection. Design optimization of barriers using bandgap and band-offset tailorability of InAs/GaSb/AlSb superlattice system, their advantages and evolution of heterostructure designs are discussed for both the regimes. Dark current densities of 1.6 × 10<sup>-7</sup> and 1.42 × 10<sup>-5</sup> A/cm<sup>2</sup> are measured at 77 K for midwave and longwave detectors with cutoff wavelengths of 5 and 10 μm, respectively. Responsivities of 1.3 (QE = 38%) and 1.66 A/W (QE = 23.5%) are measured at 4.2 and 8.7 μm for the midwave and longwave, respectively, at 77 K. Shot noise limited peak detectivity of 8.9 × 10<sup>12</sup> and 7.7×10<sup>11</sup> cm-Hz<sup>1/2</sup>-W<sup>-1</sup> are observed at -10 and -40 mV for midwave infrared and longwave infrared detectors, respectively, at 77 K.


Proceedings of SPIE, the International Society for Optical Engineering | 2006

Status of two-color and large format HgCdTe FPA technology at Raytheon Vision Systems

E. P. G. Smith; R. E. Bornfreund; I. Kasai; L. T. Pham; E. A. Patten; J. M. Peterson; J. A. Roth; Brett Z. Nosho; T. J. De Lyon; J. E. Jensen; James Bangs; S. M. Johnson; W. A. Radford

Raytheon Vision Systems (RVS) is developing two-color and large format single color FPAs fabricated from molecular beam epitaxy (MBE) grown HgCdTe triple layer heterojunction (TLHJ) wafers on CdZnTe substrates and double layer heterojunction (DLHJ) wafers on Si substrates, respectively. MBE material growth development has resulted in scaling TLHJ growth on CdZnTe substrates from 10cm2 to 50cm2, long-wavelength infrared (LWIR) DLHJ growth on 4-inch Si substrates and the first demonstration of mid-wavelength infrared (MWIR) DLHJ growth on 6-inch Si substrates with low defect density (<1000cm-2) and excellent uniformity (composition<0.1%, cut-off wavelength Δcenter-edge<0.1μm). Advanced FPA fabrication techniques such as inductively coupled plasma (ICP) etching are being used to achieve high aspect ratio mesa delineation of individual detector elements with benefits to detector performance. Recent two-color detectors with MWIR and LWIR cut-off wavelengths of 5.5μm and 10.5μm, respectively, exhibit significant improvement in 78K LW performance with >70% quantum efficiency, diffusion limited reverse bias dark currents below 300pA and RA products (zero field-of-view, +150mV bias) in excess of 1×103 Ωcm2. Two-color 20μm unit-cell 1280×720 MWIR/LWIR FPAs with pixel response operability approaching 99% have been produced and high quality simultaneous imaging of the spectral bands has been achieved by mating the FPA to a readout integrated circuit (ROIC) with Time Division Multiplexed Integration (TDMI). Large format mega pixel 20μm unit-cell 2048×2048 and 25μm unit-cell 2560×512 FPAs have been demonstrated using DLHJ HgCdTe growth on Si substrates in the short wavelength infrared (SWIR) and MWIR spectral range. Recent imaging of 30μm unit-cell 256×256 LWIR FPAs with 10.0-10.7μm 78K cut-off wavelength and pixel response operability as high as 99.7% show the potential for extending HgCdTe/Si technology to LWIR wavelengths.


Optical Science and Technology, SPIE's 48th Annual Meeting | 2003

Two-color HgCdTe infrared staring focal plane arrays

E. P. G. Smith; L. T. Pham; G. M. Venzor; Elyse Norton; M. D. Newton; Paul Goetz; Valerie Randall; Gregory K. Pierce; E. A. Patten; Raymond A. Coussa; Ken Kosai; W. A. Radford; John Edwards; S. M. Johnson; Stefan T. Baur; J. A. Roth; Brett Z. Nosho; John E. Jensen; Randolph E. Longshore

Raytheon Vision Systems (RVS) in collaboration with HRL Laboratories is contributing to the maturation and manufacturing readiness of third-generation two-color HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256x256 30μm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) spectral regions. FPAs configured for MWIR/MWIR, MWIR/LWIR and LWIR/LWIR detection are used for target identification, signature recognition and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer-heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all two-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single mesa, single indium bump, and sequential mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.


Proceedings of SPIE | 2012

High operating temperature mid-wavelength infrared HgCdTe photon trapping focal plane arrays

K. D. Smith; Justin Gordon Adams Wehner; Roger W. Graham; J. E. Randolph; A. M. Ramirez; G. M. Venzor; K.R. Olsson; M. F. Vilela; E. P. G. Smith

This paper investigates arrays of HgCdTe photon trapping detectors. Performance of volume reduced single mesas is compared to volume reduced photon trap detectors. Good agreement with model trends is observed. Photon trap detectors exhibit improved performance compared to single mesas, with measured noise equivalent temperature difference (NEDT) of 40 mK and 100 mK at temperatures of 180 K and 200 K, with good operability. Performance as a function of temperature has also been investigated.


Proceedings of SPIE | 2010

Mid-wavelength InAsSb detectors based on nBn design

A. Khoshakhlagh; S. Myers; E. Plis; M. N. Kutty; B. Klein; N. Gautam; H. S. Kim; E. P. G. Smith; David R. Rhiger; S. M. Johnson; S. Krishna

The development of InAsSb detectors based on the nBn design for the mid-wave infrared (MWIR) spectral region is discussed. Comparisons of optical and electrical properties of InAsSb photodetectors with two different barrier material, namely, AlAs 0.15Sb0.75 (structure A) and AlAs0.10Sb0.9 (structure B) are reported. The dark current density in the AlAs0.15Sb0.85 is lower possibly due to the larger valence band offset. Clear room temperature spectral responses is observed and a specific detectivity (D*) of 1.4x1012 and 1.01x1012 cmHz1/2/W at 0.2 V, and a responsivity of 0.87 and 1.66 A/W under 0.2 V biasing at 77 K and 3.5 μm, assuming unity gain, was obtained for structures A and B, respectively.


Proceedings of SPIE | 2009

Large-format HgCdTe focal plane arrays for dual-band long-wavelength infrared detection

E. P. G. Smith; A. M. Gallagher; Thomas Kostrzewa; M. L. Brest; Roger W. Graham; C. L. Kuzen; E. T. Hughes; T. F. McEwan; G. M. Venzor; E. A. Patten; W. A. Radford

Raytheon Visions Systems (RVS) is furthering its capability to deliver state-of-the-art high performance large format HgCdTe focal plane arrays (FPAs) for dual-band long-wavelength infrared (LWIR) detection. Missile seekers are designed to acquire targets of interest at long ranges and discriminate targets from clutter. The use of dual-band long wavelength infrared detector technology provides the ability for these seekers to combine these operations into the same package with enhanced performance. Increasing the format size of dual-band longwavelength FPAs and tailoring the detector design for specific long-wavelength bands enables seekers to be designed for increased field-of-view, longer target acquisition ranges, and improved accuracy. This paper will review in further detail the aspects of detector design, MBE wafer growth, wafer fabrication, and detector characterization that are contributing to development and demonstration of high performance large format dual-band LWIR FPAs at RVS.


Proceedings of SPIE | 2011

Lateral diffusion of minority carriers in InAsSb-based nBn detectors

E. Plis; S. Myers; M. N. Kutty; J. Mailfert; E. P. G. Smith; S. M. Johnson; S. Krishna

We report on the investigation of lateral diffusion of minority carriers in InAsSb based photodetectors with the nBn design. Diffusion lengths (DL) were extracted from temperature dependent I-V measurements. The behavior of DL as a function of applied bias, temperature, and composition of the barrier layer was investigated. The obtained results suggest that lateral diffusion of minority carriers is not the limiting factor for InAsSb based nBn MWIR detector performance at high temperatures (> 200K). The detector with an As mole fraction of 10% in the barrier layer has demonstrated values of DL as low as 7 μm (Vb = 0.05V) at 240K.


Quantum sensing and nanophotonic devices. Conference | 2005

Status of HgCdTe/Si Technology for Large Format Infrared Focal Plane Arrays

S. M. Johnson; W. A. Radford; A. A. Buell; M. F. Vilela; J. M. Peterson; Jeffrey J. Franklin; R. E. Bornfreund; A. C. Childs; G. M. Venzor; M. D. Newton; E. P. G. Smith; Lee M. Ruzicka; Gregory K. Pierce; D. D. Lofgreen; Terence J. de Lyon; John E. Jensen

HgCdTe offers significant advantages over other semiconductors which has made it the most widely utilized variable-gap material in infrared focal plane array (FPA) technology. However, one of the main limitations of the HgCdTe materials system has been the size of lattice-matched bulk CdZnTe substrates, used for epitaxially-grown HgCdTe, which are 30 cm2 in size for production and have historically been difficult and expensive to scale in size. This limitation does not adequately support the increasing demand for larger FPA formats which now require sizes up to and beyond 2048 x 2048 and only a single die can be printed per wafer. Heteroepitaxial Si-based substrates offer a cost-effective technology that can be more readily scaled to large wafer sizes. Most of the effort in the IR community in the last 10 years has focused on growing HgCdTe directly on (112)Si substrates by MBE. At Raytheon we have scaled the MBE (112)HgCdTe/Si process originally developed at HRL for 3-in wafers, first to 4-in wafers and more recently to 6 in wafers. We have demonstrated a wide range of MWIR FPA formats up to 2560 x 512 in size and have found that their performance is comparable to arrays grown on bulk CdZnTe substrates by either MBE or LPE techniques. More recent work is focused on extending HgCdTe/Si technology to LWIR wavelengths. The goal of this paper is to review the current status of HgCdTe/Si technology both at Raytheon and the published work available from other organizations.

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S. Myers

University of New Mexico

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E. Plis

University of New Mexico

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S. Krishna

University of New Mexico

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