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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.
IEEE Transactions on Electron Devices | Year: 2011

Infrared detectors require cryogenic operation to suppress dark current, which is typically limited by Auger processes in narrow-band-gap semiconductor materials. Device structures designed to reduce carrier density under nonequilibrium reverse-bias operation provide a means to suppress Auger generation and to reduce dark current and subsequent cryogenic cooling requirements. This study closely examines mercury cadmium telluride (HgCdTe) p+nu/n+device structures exhibiting Auger suppression, comparing the simulated device behavior and performance metrics to those obtained for conventional HgCdTe p+/nudetector structures. Calculated detectivity values of high-operating-temperature and double-layer planar heterojunction devices demonstrate consistently higher background limited performance (BLIP) temperatures over a range of cutoff wavelengths. BLIP temperature improvements of Δ TBLIP ∼ 48\K and 43 K were extracted from simulations for midwavelength infrared and long wavelength infrared devices, respectively. These studies predict that Auger-suppressed detectors provide a significant advantage over conventional detectors with an increased operating temperature of approximately 40 K for equivalent performance for devices with cutoff wavelength in the range of 512 μm. © 2006 IEEE. Source

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. Source

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

A method of forming a diode comprises the steps of forming an extraction region of a first conductivity type, forming an active region of a second conductivity type that is opposite the first conductivity type, and forming an exclusion region of the second conductivity type to be adjacent the active region. The active region is formed to be adjacent to the extraction region and along a reverse bias path of the extraction region and the exclusion region does not resupply minority carriers while removing majority carriers. At least one of the steps of forming the exclusion region and forming the extraction region includes the additional step of forming a barrier that substantially reduces the flow of the carriers that flow toward the active region, but does not rely on a diffusion length of the carriers to block the carriers.

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.

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