Terahertz-Emitting Silicon-Germanium Devices

2002 ◽  
Vol 744 ◽  
Author(s):  
Ralph T. Troeger ◽  
Thomas N. Adam ◽  
Samit K. Ray ◽  
Pengcheng Lv ◽  
Ulrike Lehmann ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Far Infrared ◽  
Infrared Emission ◽  
X Ray Diffraction ◽  
Wide Range ◽  
Spectral Peaks ◽  
Current Densities ◽  
Ftir Spectrometer ◽  
Lock In ◽  
Good Agreement

ABSTRACTIn this paper we report on far-infrared emission in the 1–12 THz frequency range from strained SiGe structures. Pseudomorphic superlattices were grown by Molecular Beam Epitaxy (MBE) at the relatively low substrate temperature of 400°C to prevent germanium segregation. Layer thicknesses, composition, and crystallinity were confirmed by high-resolution X-ray diffraction. Devices were designed to produce confined hole states with various energy separations. Mesa devices were etched in a reactive-ion etching system and tested for edge emission over a wide range of drive currents using an FTIR spectrometer in step-scan mode. THz emission was observed in pulsed mode at current densities as low as 50 A/cm2 and at temperatures as high as 50 K, using a liquid-helium-cooled silicon bolometer detector with a lock-in amplifier. Emission spectral peaks occurred at 7.9 and 9.36 THz for two different samples, in good agreement with k·p calculations.

X-ray Diffraction Study of Amorphous NixZr(100-x)-Alloys Prepared by Melt-Spinning

1991 ◽  
Vol 46 (11) ◽  
pp. 947-950
Author(s):  
W.-M. Kuschke ◽  
P. Lamparter ◽  
S. Steeb
Keyword(s):  
Melt Spinning ◽  
Pair Correlation ◽  
Nickel Concentration ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
Wide Range ◽  
Good Agreement

AbstractAmorphous Ni-Zr-alloys can be prepared by melt-spinning within a wide range of composition. Studies by X-ray diffraction yielded structure factors, pair correlation functions, total coordination numbers and atomic distances in dependence on the nickel concentration in the range of 25 up to 45 atomic percent. The change of the total coordination number and atomic distances turned out to be linear with the composition in this range. This is in good agreement with the linear composition dependence of the superconducting transition temperature, magnetic susceptibility, crystallization temperature, and electrical resistivity in the investigated range of composition.

scholarly journals Microwave-Assisted Preparation of Zinc-Doped β-Tricalcium Phosphate for Orthopedic Applications

2020 ◽  
Author(s):  
Ali Taha Saleh ◽  
Dheyaa Alameri
Keyword(s):  
Tricalcium Phosphate ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Assisted ◽  
Ftir Spectrometer ◽  
Diffraction Peaks ◽  
Orthopedic Applications ◽  
The Degree Of Crystallinity ◽  
Good Agreement

A novel two-step methodology delivering zinc into the structure of β-tricalcium phosphate (β-TCP) has been investigated. Incorporating wet precipitation of calcium-deficient apatite [Ca9-xZnx(HPO4)(PO4)5(OH)] (x = 0.00–1.00 mol) using a microwave-assisted process followed by two-hour calcination at 1000 °C has been conducted to generate a ratio of 1.48 of Zn doped β-TCP. The products were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectrometer, and field emission scanning electron microscope (FESEM). Our results confirmed that the product was crystalline Zn2+-doped β-tricalcium phosphate. The incorporation of Zn+2 into the β-TCP lattice resulted in a shifting of diffraction peaks to higher 2θ values, which were attributed to the substitution of larger-sized Ca+2 ions with smaller-sized Zn2+ ions. A reduction in the intensity of the XRD peaks was also observed due to the reduction in the degree of crystallinity of the samples. Lattice parameters along the a and c-axis showed a gradual decrease in length with an increase in the amount of Zn2+ doping. This decrease was attributed to the replacement of Ca+2 ion by the smaller-sized Zn2+ ions. The microstructure of the powders consisted of microscale aggregates fused together. EDX analysis of all samples showed that the Zn2+ doping had successfully taken place and the amount of Zn2+ present in the samples was in good agreement with the theoretical values.

Silicon germanium quantum cascade heterostructures for far-infrared emission

2002 ◽  
Author(s):  
Robert W. Kelsall ◽  
Zoran Ikonic ◽  
Paul Harrison ◽  
Stephen A. Lynch ◽  
Robert Bates ◽  
...  
Keyword(s):  
Silicon Germanium ◽  
Far Infrared ◽  
Infrared Emission ◽  
Quantum Cascade

Solubility of Niobium(V) under Cementitious Conditions: Importance of Ca-niobate

2004 ◽  
Vol 824 ◽  
Author(s):  
Caterina Talerico ◽  
Michael Ochs ◽  
Eric Giffaut
Keyword(s):  
Solid Phase ◽  
Empirical Relation ◽  
Oxide Phase ◽  
X Ray Diffraction ◽  
Ph Values ◽  
Wide Range ◽  
Ph Conditions ◽  
Predicted Values ◽  
Ph Range ◽  
Good Agreement

AbstractThe solubility of niobium was investigated for Ca and pH conditions relevant for cementequilibrated solutions. For the pH range considered (9.5-13.2), the dissolved Nb concentration decreases with increasing pH. Overall, experiments lead to Nb concentrations between 2·10-5 M and 2·10-9 M. For all pH values, the dissolved Nb concentration also decreases systematically with increasing Ca concentration. X-ray diffraction measurements of selected experiments confirmed the presence of a solid Ca-Nb-oxide phase, with CaNb4O11·8H2O (hochelagaite) being the most likely composition. On the basis of these findings an empirical regression model for the prediction of Nb solubility data as a function of pH and Ca concentration was derived. This empirical relation is consistent with the presence of a solubility limiting Ca-Nb solid phase and permits to predict aqueous Nb solubility values in cementitious environments over a relatively wide range of conditions. Predicted values are in good agreement with independent experimental results.

Scanning Tunneling Optical Resonance Microscopy (STORM)

2002 ◽  
Vol 738 ◽  
Author(s):  
R.P. Raffaelle ◽  
T. Gennett ◽  
J. E. Lau ◽  
P. Jenkins ◽  
S.L. Castro ◽  
...  
Keyword(s):  
Spatial Light Modulator ◽  
Tunneling Current ◽  
Scanning Tunneling ◽  
X Ray Diffraction ◽  
Light Modulator ◽  
Optical Resonance ◽  
X Ray ◽  
Lock In ◽  
Good Agreement

ABSTRACTThe ability to determine the in-situ optoelectronic behavior of semiconductor materials has become especially important as the size of device architectures is reduced and the development of complex microsystems has increased. Scanning Tunneling Optical Resonance Microscopy or STORM has the ability to interrogate the optical bandgap as a function of position within a semiconductor microstructure. This technique uses a tunable solid-state Ti sapphire laser whose output is “chopped” using a spatial light modulator and is coupled by a fiber optic to a scanning tunneling microscope in order to illuminate the tip-sample junction. The photoenhanced portion of the tunneling current is spectroscopically measured using a lock-in technique. The capabilities of this technique were verified using semiconductor microstructure calibration standards that were grown by organometallic vapor phase epitaxy (OMVPE) at the NASA Glenn Research Center. Bandgaps characterized by STORM measurements were found to be in good agreement with the bulk values determined by transmission spectroscopy, photoluminescence, and with the theoretical values that were based on x-ray diffraction results.

scholarly journals The case for thermalization as a contributor to the [C ii] deficit

2021 ◽  
Vol 503 (1) ◽  
pp. 911-919
Author(s):  
Jessica Sutter ◽  
Daniel A Dale ◽  
Karin Sandstrom ◽  
J D T Smith ◽  
Alberto Bolatto ◽  
...  
Keyword(s):  
Far Infrared ◽  
Infrared Emission ◽  
Continuum Emission ◽  
H Ii Regions ◽  
Observable Universe ◽  
Star Forming ◽  
Star Forming Regions ◽  
Wide Range ◽  
Nearby Galaxies ◽  
Selection Of

ABSTRACT The [C ii] deficit, which describes the observed decrease in the ratio of [C ii] 158 μm emission to continuum infrared emission in galaxies with high star formation surface densities, places a significant challenge to the interpretation of [C ii] detections from across the observable universe. In an attempt to further decode the cause of the [C ii] deficit, the [C ii] and dust continuum emission from 18 Local Volume galaxies has been split based on conditions within the interstellar medium where it originated. This is completed using the Key Insights in Nearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH) and Beyond the Peak (BtP) surveys and the wide-range of wavelength information, from UV to far-infrared emission lines, available for a selection of star-forming regions within these samples. By comparing these subdivided [C ii] emissions to isolated infrared emission and other properties, we find that the thermalization (collisional de-excitation) of the [C ii] line in H ii regions plays a significant role in the deficit observed in our sample.

Structure and Properties Research of Multi-Antibacterial Polyamide Fibers

2011 ◽  
Vol 331 ◽  
pp. 179-183
Author(s):  
Wei Wei Sun ◽  
Hua Zhang ◽  
Yong Kai Zhou
Keyword(s):  
Antibacterial Effect ◽  
Far Infrared ◽  
Infrared Emission ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ions ◽  
Polyamide Fibers ◽  
Scanning Electron ◽  
Structure Properties

To explore the effect of multi-antibacterial powders on the polyamide fibers, we analyzed the structure and properties of the polyamide fibers in this paper, which have features of antibacterial, far-infrared emission and negative oxygen ions emission. The effects of adding multi-antibacterial power were tested by Scanning Electron Microscopy and spectrum tests, X-ray diffraction, thermal analysis and infrared spectroscopy. Our data indicated that multi-antibacterial polyamide fibers have excellent antibacterial effect, good far-infrared emission and the negative oxygen ions emission features, while have little affect on polyamide fibers’ structure properties.

scholarly journals Dust in and around galaxies: dust in cluster environments and its impact on gas cooling

2019 ◽  
Vol 487 (4) ◽  
pp. 4870-4883 ◽  
Author(s):  
Mark Vogelsberger ◽  
Ryan McKinnon ◽  
Stephanie O’Neil ◽  
Federico Marinacci ◽  
Paul Torrey ◽  
...  
Keyword(s):  
High Temperature ◽  
Far Infrared ◽  
Infrared Emission ◽  
Metal Line ◽  
Wide Range ◽  
Dust Mass ◽  
Gas Cooling ◽  
Hydrodynamical Simulations ◽  
Ion Collision ◽  
Dust Evolution

Abstract Simulating the dust content of galaxies and their surrounding gas is challenging due to the wide range of physical processes affecting the dust evolution. Here we present cosmological hydrodynamical simulations of a cluster of galaxies, $M_\text{200,crit}=6 \times 10^{14}{\, \rm M_\odot }$, including a novel dust model for the moving mesh code arepo. This model includes dust production, growth, supernova-shock-driven destruction, ion-collision-driven thermal sputtering, and high-temperature dust cooling through far-infrared reradiation of collisionally deposited electron energies. Adopting a rather low thermal sputtering rate, we find, consistent with observations, a present-day overall dust-to-gas ratio of ∼2 × 10−5, a total dust mass of ${\sim } 2\times 10^9{\, \rm M_\odot }$, and a dust mass fraction of ∼3 × 10−6. The typical thermal sputtering time-scales within ${\sim } 100\, {\rm kpc}$ are around ${\sim } 10\, {\rm Myr}$, and increase towards the outer parts of the cluster to ${\sim } 10^3\, {\rm Myr}$ at a cluster-centric distance of $1\, {\rm Mpc}$. The condensation of gas-phase metals into dust grains reduces high-temperature metal-line cooling, but also leads to additional dust infrared cooling. The additional infrared cooling changes the overall cooling rate in the outer parts of the cluster, beyond ${\sim } 1\, {\rm Mpc}$, by factors of a few. This results in noticeable changes of the entropy, temperature, and density profiles of cluster gas once dust formation is included. The emitted dust infrared emission due to dust cooling is consistent with observational constraints.

Effect of Tourmaline-Doped on the Far Infrared Emission of Iron Ore Tailings Ceramics

2016 ◽  
Vol 16 (4) ◽  
pp. 3777-3780 ◽  
Author(s):  
Jie Liu ◽  
Junping Meng ◽  
Jinsheng Liang ◽  
Hongchen Zhang ◽  
Xiaoyang Gu
Keyword(s):  
Production Cost ◽  
Iron Ore ◽  
Lattice Strain ◽  
Far Infrared ◽  
Infrared Emission ◽  
Infrared Emissivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Ore Tailings ◽  
The World

Iron ore tailings as secondary resources have been of great importance to many countries in the world. Their compositions are similar to that of infrared emission ceramics, but there are few reports about it. In addition, tourmaline has high infrared emission properties due to its unique structure. With the purpose of expanding functional utilization of iron ore tailings, as well as reducing the production cost of far infrared ceramics, a new kind of far infrared emission ceramics was prepared by using iron ore tailings, calcium carbonate, silica, and natural tourmaline. The ceramics powders were characterized by Fourier transform infrared spectroscope, X-ray diffraction and scanning electron microscopy, respectively. The results show that after being sintered at 1065 °C, the percentage of pseudobrookite and lattice strain of samples increased with increasing the elbaite content. Furthermore, the added tourmaline was conducive to the densification sintering of ceramics. The appearance of Li–O vibration at 734.73 cm−1, as well as the strengthened Fe–O vibration at 987.68 cm−1 were attributed to the formation of Li0.375Fe1.23Ti1.4O5 solid solution, which led the average far infrared emissivity of ceramics increase from 0.861 to 0.906 within 8–14 μm.

scholarly journals Separate Universe calibration of the dependence of halo bias on cosmic web anisotropy

2020 ◽  
Vol 499 (3) ◽  
pp. 4418-4431 ◽  
Author(s):  
Sujatha Ramakrishnan ◽  
Aseem Paranjape
Keyword(s):  
Dark Matter ◽  
High Precision ◽  
Gaussian Distribution ◽  
Initial Perturbation ◽  
Analytical Framework ◽  
Web Environment ◽  
Wide Range ◽  
Galaxy Assembly ◽  
Very High ◽  
Good Agreement

ABSTRACT We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias b1 and b2 on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed mass and cosmic web tidal anisotropy α to an infinite wavelength initial perturbation. We augment our measurements with an analytical framework developed in earlier work that exploits the near-lognormal shape of the distribution of α and results in very high precision calibrations. We present convenient fitting functions for the dependence of b1 and b2 on α over a wide range of halo mass for redshifts 0 ≤ z ≤ 1. Our calibration of b2(α) is the first demonstration to date of the dependence of non-linear bias on the local web environment. Motivated by previous results that showed that α is the primary indicator of halo assembly bias for a number of halo properties beyond halo mass, we then extend our analytical framework to accommodate the dependence of b1 and b2 on any such secondary property that has, or can be monotonically transformed to have, a Gaussian distribution. We demonstrate this technique for the specific case of halo concentration, finding good agreement with previous results. Our calibrations will be useful for a variety of halo model analyses focusing on galaxy assembly bias, as well as analytical forecasts of the potential for using α as a segregating variable in multitracer analyses.

Sign in / Sign up

Export Citation Format

Share Document