Bandgap-Engineering of HgCdTe for Two-Color Ir Detector Arrays BY Movpe

1997 ◽  
Vol 484 ◽  
Author(s):  
P. Mitra ◽  
F. C. Case ◽  
S. L. Barnes ◽  
M. B. Reine ◽  
P. O'Dette ◽  
...  
Keyword(s):  
Depth Profile ◽  
Bandgap Engineering ◽  
Iodine Doping ◽  
Etch Pits ◽  
Ir Detector ◽  
Double Crystal ◽  
Detector Arrays ◽  
Long Wavelength ◽  
Double Heterojunction

AbstractRecent results on MOVPE growth of multilayer two-color HgCdTe detectors, for simultaneous and independent detection of medium wavelength (MW, 3–5 μm) and long wavelength (LW, 8–12 μm) bands, are reported. The structures are grown in situ on lattice matched (100) CdZnTe in the double-heterojunction p-n-N-P configuration. A barrier layer is placed between the LW and MW absorber layers to prevent diffusion of MW photocarriers into the LW junction and thereby eliminate spectral crosstalk. X-ray double crystal rocking curve widths are ∼ 45 arc-secs, indicating good epitaxial quality. SIMS depth profile measurements of these 28 μm thick structures show well-defined alloy compositions, and arsenic and iodine doping. SIMS data on a series of thirteen films show that good run-to-run repeatability is obtained on thicknesses, compositions, and dopant levels with values close to the device design targets. Depth profile of etch pits through the thickness of the films show etch pit densities in the range of 8×105-5×106 cm−2.

SUPERLATTICE MATERIALS FOR THE NEXT GENERATION OF LONG WAVELENGTH INFRARED DETECTORS

2000 ◽  
Vol 10 (01) ◽  
pp. 47-53
Author(s):  
G. J. BROWN ◽  
F. SZMULOWICZ ◽  
K. MAHALINGAM ◽  
A. SAXLER ◽  
R. LINVILLE ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Infrared Imaging ◽  
Infrared Detector ◽  
High Sensitivity ◽  
Next Generation ◽  
Ir Detector ◽  
Detector Arrays ◽  
Long Wavelength ◽  
Detector Materials ◽  
Long Wavelength Infrared

New infrared (IR) detector materials with high sensitivity, multi-spectral capability, improved uniformity and lower manufacturing costs are required for numerous space-based infrared imaging applications. To meet these stringent requirements, new materials must be designed and grown using semiconductor heterostructures, such as quantum wells and superlattices, to tailor new optical and electrical properties unavailable in the current generation of materials. One of the most promising materials is a strained layer supperlattice (SLS) composed of thin InAs and GaInSb layers. While this material shows theoretical and early experimental promise, there are still several materials growth and processing issues to be addressed before this material can be transitioned to the next generation of infrared detector arrays. Our research is focused on addressing the basic materials design, growth, optical properties, and electronic transport issue of these superlattices.

scholarly journals Introduction

1995 ◽  
Vol 167 ◽  
pp. 3-7
Author(s):  
A. G. Davis Philip
Keyword(s):  
Large Field ◽  
Direct Imaging ◽  
Ir Detector ◽  
New Developments ◽  
Detector Arrays ◽  
Array Detectors ◽  
Poster Sessions ◽  
Array Technology ◽  
The Subject ◽  
Scientific Results

A short introduction to the subject of the meeting, IAU Symposium No. 167, New Developments in Array Technology and Applications is given. CCD and Array detectors have become the detectors of choice at optical observatories all over the world. Direct imaging, photometry and spectroscopy are all vastly improved as a result. Thirteen IAU Commissions joined in sponsoring this meeting which indicates the wide interest in this subject. In the five days of the symposium the following topics were discussed: New Developments in CCD Technology, New Developments in IR Detector Arrays, Direct Imaging with CCDs and Other Arrays, Spectroscopy with CCDs and Other Arrays and Large Field Imaging with Array Mosaics. A few papers concerning Astrometry with CCDs were given in the poster sessions. Scientific results were also presented in the poster sessions.

scholarly journals Sulfur bacteria promote dissolution of authigenic carbonates at marine methane seeps

2021 ◽  
Author(s):  
Dalton J. Leprich ◽  
Beverly E. Flood ◽  
Peter R. Schroedl ◽  
Elizabeth Ricci ◽  
Jeffery J. Marlow ◽  
...  
Keyword(s):  
Carbonate Rocks ◽  
Sulfur Oxidation ◽  
Methane Seeps ◽  
Etch Pits ◽  
Active Dissolution ◽  
Authigenic Carbonates ◽  
Sulfur Bacteria ◽  
Sulfur Oxidizing ◽  
Sulfur Oxidizing Bacteria

AbstractCarbonate rocks at marine methane seeps are commonly colonized by sulfur-oxidizing bacteria that co-occur with etch pits that suggest active dissolution. We show that sulfur-oxidizing bacteria are abundant on the surface of an exemplar seep carbonate collected from Del Mar East Methane Seep Field, USA. We then used bioreactors containing aragonite mineral coupons that simulate certain seep conditions to investigate plausible in situ rates of carbonate dissolution associated with sulfur-oxidizing bacteria. Bioreactors inoculated with a sulfur-oxidizing bacterial strain, Celeribacter baekdonensis LH4, growing on aragonite coupons induced dissolution rates in sulfidic, heterotrophic, and abiotic conditions of 1773.97 (±324.35), 152.81 (±123.27), and 272.99 (±249.96) μmol CaCO3 • cm−2 • yr−1, respectively. Steep gradients in pH were also measured within carbonate-attached biofilms using pH-sensitive fluorophores. Together, these results show that the production of acidic microenvironments in biofilms of sulfur-oxidizing bacteria are capable of dissolving carbonate rocks, even under well-buffered marine conditions. Our results support the hypothesis that authigenic carbonate rock dissolution driven by lithotrophic sulfur-oxidation constitutes a previously unknown carbon flux from the rock reservoir to the ocean and atmosphere.

Eigenstructure approach to directions-of-arrival estimation in IR detector arrays

1987 ◽  
Vol 26 (2) ◽  
pp. 199 ◽  
Author(s):  
Daniel Spielman ◽  
A. Paulraj ◽  
Thomas Kailath
Keyword(s):  
Ir Detector ◽  
Detector Arrays

Investigation of Magnetic Order in Iron Oxide-Nickel Oxide Superlattices with Modulation Wavelength Less Than 80 Å

1991 ◽  
Vol 231 ◽  
Author(s):  
S. D. Berry ◽  
D. M. Lind ◽  
G. Chern ◽  
H. Mathias ◽  
L. R. Testardi
Keyword(s):  
Magnetic Order ◽  
Spontaneous Magnetization ◽  
X Ray Diffraction ◽  
High Crystalline Quality ◽  
X Ray ◽  
Long Wavelength ◽  
Saturation Moment ◽  
Very High ◽  
Modulation Wavelength

AbstractWe have investigated the magnetic order, using SQUID magnetometry, for short modulation wavelength Fe3O4/NiO superlattices, grown on single crystal MgO. Ferrimagnetic Fe3O4 has a saturation moment of ~500 emu/cm3 at 0 K and a Curie temperature of 858 K, while bulk NiO is antiferromagnetic with a NMel temperature of 525 K. Very high crystalline quality with little interdiffusion is indicated by X-ray diffraction, SEM, optical microscopy, and in-situ RHEED, and the samples show highly anisotropic electrical conductivity which also indicates the strong modulation present. Long wavelength samples (Amod > 200 Å) have a behavior only slightly different from that expected from bulk Fe3O4, but for Amod<80 Å, spontaneous magnetization is replaced by paramagnetism, with weak temperature dependence (not I/T) from 5 K to 400 K.

scholarly journals Vibration measurements of high-heat-load monochromators for DESY PETRA III extension

2015 ◽  
Vol 22 (4) ◽  
pp. 879-885 ◽  
Author(s):  
Paw Kristiansen ◽  
Jan Horbach ◽  
Ralph Döhrmann ◽  
Joachim Heuer
Keyword(s):  
Measurement Techniques ◽  
High Heat ◽  
Direct Drive ◽  
Double Crystal ◽  
Relative Pitch ◽  
Double Crystal Monochromator ◽  
Synchrotron Beam ◽  
High Heat Load ◽  
Low Emittance

The requirement for vibrational stability of beamline optics continues to evolve rapidly to comply with the demands created by the improved brilliance of the third-generation low-emittance storage rings around the world. The challenge is to quantify the performance of the instrument before it is installed at the beamline. In this article, measurement techniques are presented that directly and accurately measure (i) the relative vibration between the two crystals of a double-crystal monochromator (DCM) and (ii) the absolute vibration of the second-crystal cage of a DCM. Excluding a synchrotron beam, the measurements are conducted underin situconditions, connected to a liquid-nitrogen cryocooler. The investigated DCM utilizes a direct-drive (no gearing) goniometer for the Bragg rotation. The main causes of the DCM vibration are found to be the servoing of the direct-drive goniometer and the flexibility in the crystal cage motion stages. It is found that the investigated DCM can offer relative pitch vibration down to 48 nrad RMS (capacitive sensors, 0–5 kHz bandwidth) and absolute pitch vibration down to 82 nrad RMS (laser interferometer, 0–50 kHz bandwidth), with the Bragg axis brake engaged.

In Situ Fabrication of 3D Octahedral g-C3 N4 /BiFeWO x Double-Heterojunction for Highly Selective CO2 Photoreduction to CO Under Visible Light

ChemCatChem ◽  
2018 ◽  
Vol 10 (20) ◽  
pp. 4578-4585 ◽  
Author(s):  
Yanan Wang ◽  
Yiqing Zeng ◽  
Shipeng Wan ◽  
Wei Cai ◽  
Fujiao Song ◽  
...  
Keyword(s):  
Visible Light ◽  
Co2 Photoreduction ◽  
In Situ Fabrication ◽  
Double Heterojunction

scholarly journals Twistable electronics with dynamically rotatable heterostructures

Science ◽  
2018 ◽  
Vol 361 (6403) ◽  
pp. 690-693 ◽  
Author(s):  
Rebeca Ribeiro-Palau ◽  
Changjian Zhang ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
James Hone ◽  
...  
Keyword(s):  
Rotation Angle ◽  
Electronic Devices ◽  
Long Wavelength ◽  
New Class ◽  
On Demand ◽  
Device Architecture ◽  
Two Dimensional Materials ◽  
Electronic Response ◽  
Small Rotation

In heterostructures of two-dimensional materials, electronic properties can vary dramatically with relative interlayer angle. This effect makes it theoretically possible to realize a new class of twistable electronics in which properties can be manipulated on demand by means of rotation. We demonstrate a device architecture in which a layered heterostructure can be dynamically twisted in situ. We study graphene encapsulated by boron nitride, where, at small rotation angles, the device characteristics are dominated by coupling to a long-wavelength moiré superlattice. The ability to investigate arbitrary rotation angle in a single device reveals features of the optical, mechanical, and electronic response in this system not captured in static rotation studies. Our results establish the capability to fabricate twistable electronic devices with dynamically tunable properties.

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