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Bolingbrook, IL, United States

Itsuno A.M.,University of Michigan | Phillips J.D.,University of Michigan | Velicu S.,EPIR Technologies, Inc.
Applied Physics Letters | Year: 2012

A unipolar, barrier-integrated HgCdTe nBn photodetector with all n-type doping and a type-I band lineup is experimentally demonstrated. Planar mid-wave infrared (MWIR) nBn devices exhibit current-voltage (I-V) characteristics that are consistent with band inversion in reverse bias, indicating a barrier-influenced behavior. Dark current saturation is observed beyond a reverse bias of approximately -0.8 V. Bias-dependent photoresponse is observed in the mid-wave infrared with a cut-off wavelength around 5.7 m. Numerical modeling based on experimental results predicts an internal peak quantum efficiency of approximately 66%. © 2012 American Institute of Physics.

Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 149.99K | Year: 2012

To satisfy the Army"s needs for the detection and identification of chemical and biological compounds and agents present in improvised explosive devices, we propose to develop a miniaturized infrared (IR) imaging spectrometer consisting of a HgCdTe-based IR focal plane array (IRFPA) coupled with a Fabry-Perot interferometer, by combining microelectromechanical systems (MEMS) technology with HgCdTe IR detector technologies. MEMS technology will be used to tune the sensor wavelength, allowing for multiple wavelength detection. All IRFPA pixels are tuned to specific wavelengths and a hyperspectral image cube is obtained by capturing an image at each wavelength of interest. During Phase I of the project we will perform optical, electronic and system studies and will develop pattern recognition algorithms for quantitative spectral decomposition and compound identification. We will design the interferometer cavity, study the materials for Bragg reflectors and perform finite element modeling of the mechanical displacements. We will study various beam structures, simulate the electrostatic actuation and determine the optimal actuation voltages. We will build a characterization set-up to assess the sensitivity, selectivity, false positive rates and probability of detection of the sensor. These figures of merit will be compared with those obtained in standard Fourier transform setups

Agency: Department of Defense | Branch: Defense Advanced Research Projects Agency | Program: SBIR | Phase: Phase II | Award Amount: 1.50M | Year: 2015

We propose the development of a near infrared/short wavelength infrared (NIR/SWIR) sensor based on molecular beam epitaxy (MBE) mercury cadmium telluride (HgCdTe) designed for room-temperature operation in the 0.4 to 1.3 micron spectral range for the next generation of night vision goggles (NVGs), weapon sights, and handheld or airborne systems. The sensor will compete as a low cost and high performance alternative to NIR InGaAs-based cameras by providing reduced fabrication costs. This proposed effort will fabricate HgCdTe NIR/SWIR sensors on silicon substrates with room-temperature spectral response down to 0.4 micron wavelength after the removal of the Si substrates. The potential benefit to DARPA of the proposed program will be a low cost camera technology that can be used in NVGs required by SOCOM, the Marines and the Army. EPIRs proprietary MBE processes offer another advantage, namely they will allow for the fabrication of in situ double sided passivated structures. Such structures are needed by DRS Technologies, a major DoD manufacturer of NVGs and other infrared products. They can be used in the DRS high density vertically integrated photodiode (HDVIP) process to fabricate 640x480 format, 12 micron pitch and 1280x960 format, 6 micron pitch FPA products for many applications.

Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase II | Award Amount: 779.97K | Year: 2010

The proposed Phase II effort will focus on the fabrication and testing of high performance 640x512 long wavelength infrared (LWIR) type-II strained layer superlattice detector arrays. The effort will start with the modeling of devices and arrays, followed by improving the understanding of bulk defects to enhance carrier lifetimes. Passivation studies will continue based on the Phase I foundation, with an emphasis on stacked passivation layers with enhanced robustness. Molecular beam epitaxial growth and fabrication of nBn structures with low dark currents and high operating temperatures will be undertaken. The dry etching of small features appropriate for short pixel pitches (15 µm) will be carried out to study etch uniformity and surface morphologies, which will be of great benefit to the realization of high performance, large format arrays. The fabricated arrays will hybridized to read out integrated circuits suitable for 15 µm pixel pitches and LWIR detectors. The focal plane arrays will be tested and characterized in-house and by our collaborator L3-Com.

Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase II | Award Amount: 429.22K | Year: 2012

The overall goal of this project is to develop a 100 degrees C temperature ALD CdTe passivation process capable of conformally passivating high aspect ratio surfaces of HgCdTe infrared detectors. The effort is comprised of first establishing the low temperature ALD process, next in fully characterizing the resulting CdTe, then implementing in-situ sample surface preparation, and finally in passivating high aspect ratio HgCdTe samples.

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