scholarly journals Negative Photoconductive Effects in Uncooled InAs Nanowire Photodetectors

2021 ◽  
Vol 9 ◽  
Author(s):  
Xingfei Zhang ◽  
Yiyun Zhang ◽  
Dong Pan ◽  
Xiaoyan Yi ◽  
Jianhua Zhao ◽  
...  
Keyword(s):  
Room Temperature ◽  
Narrow Band ◽  
Wide Spectrum ◽  
Carrier Dynamics ◽  
One Dimensional ◽  
Near Ir ◽  
Metal Semiconductor Metal ◽  
Decay Times ◽  
Inas Nanowires ◽  
Msm Structure

One-dimensional, direct, and narrow band gap indium arsenide (InAs) nanowires (NWs) have been emerging with great potentials for the next-generation wide-spectrum photodetectors. In this study, metal–semiconductor–metal (MSM) structure InAs NW-based photodetectors were fabricated by transferring MBE-grown NWs onto a sapphire substrate via a mechanical stamping method. These NW detectors exhibit strong negative photoconductive (NPC) effects, which are likely caused by the carrier dynamics in the “core-shell” structure of the NWs. Specifically, under the irradiation of a 405 nm violet laser, the maximum Idark/Ilight ratio reaches ∼102 and the NPC gain reaches 105 at a low bias voltage of 0.2 V. At room temperature, the rise and decay times of InAs NW devices are 0.005 and 2.645 s, respectively. These InAs NW devices with a high Idark/Ilight ratio and NPC gain can be potentially used in the field of vis/near-IR light communication in the future.

Crystal structure of the anticancer drug carmustine determined by X-ray powder diffraction

2021 ◽  
pp. 1-3
Author(s):  
Carina Schlesinger ◽  
Edith Alig ◽  
Martin U. Schmidt
Keyword(s):  
Crystal Structure ◽  
Anticancer Drug ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Commercial Sample ◽  
One Dimensional ◽  
X Ray ◽  
Hydrogen Bond Pattern

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P212121 with Z = 4. The lattice parameters are a = 19.6935(2) Å, b = 9.8338(14) Å, c = 4.63542(6) Å, V = 897.71(2) ų at 153 K, and a = 19.8522(2) Å, b = 9.8843(15) Å, c = 4.69793(6) Å, V = 921.85(2) ų at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.

A new one-dimensional CdIIcoordination polymer with a two-dimensional layered structure incorporating 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole and benzene-1,2-dicarboxylate ligands

2016 ◽  
Vol 72 (6) ◽  
pp. 480-484 ◽  
Author(s):  
Qiu-Ying Huang ◽  
Xiao-Yi Lin ◽  
Xiang-Ru Meng
Keyword(s):  
Layered Structure ◽  
Room Temperature ◽  
Weak Interactions ◽  
Coordination Geometry ◽  
Dimensional Chain ◽  
Two Dimensional ◽  
One Dimensional ◽  
Heterocyclic Ligand ◽  
Rich Variety ◽  
Solvent Molecules

The N-heterocyclic ligand 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and interesting properties. In the coordination polymercatena-poly[[cadmium(II)-bis[μ-benzene-1,2-dicarboxylato-κ4O1,O1′:O2,O2′]-cadmium(II)-bis{μ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole}-κ2N2:N3;κ2N3:N2] dimethylformamide disolvate], {[Cd(C8H4O4)(C11H10N4)]·C3H7NO}n, (I), each CdIIion exhibits an irregular octahedral CdO4N2coordination geometry and is coordinated by four O atoms from two symmetry-related benzene-1,2-dicarboxylate (1,2-bdic2−) ligands and two N atoms from two symmetry-related imb ligands. Two CdIIions are connected by two benzene-1,2-dicarboxylate ligands to generate a binuclear [Cd2(1,2-bdic)2] unit. The binuclear units are further connected into a one-dimensional chain by pairs of bridging imb ligands. These one-dimensional chains are further connected through N—H...O hydrogen bonds and π–π interactions, leading to a two-dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairsviaweak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.

Polar Optical Phonon Instability and Intervalley Transfer in Gallium Nitride

1998 ◽  
Vol 512 ◽  
Author(s):  
B. E. Foutz ◽  
S. K. O'leary ◽  
M. S. Shur ◽  
L. F. Eastman ◽  
B. L. Gelmont ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Analytical Model ◽  
Optical Phonon ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Polar Optical Phonon ◽  
Scattering Mechanism ◽  
Loss Mechanism ◽  
One Dimensional ◽  
Optical Phonon Scattering

ABSTRACTWe develop a simple, one-dimensional, analytical model, which describes electron transport in gallium nitride. We focus on the polar optical phonon scattering mechanism, as this is the dominant energy loss mechanism at room temperature. Equating the power gained from the field with that lost through scattering, we demonstrate that beyond a critical electric field, 114 kV/cm at T = 300 K, the power gained from the field exceeds that lost due to polar optical phonon scattering. This polar optical phonon instability leads to a dramatic increase in the electron energy, this being responsible for the onset of intervalley transitions. The predictions of our analytical model are compared with those of Monte Carlo simulations, and are found to be in satisfactory agreement.

scholarly journals Absorption and Emission Spectra for C60 Anions

1994 ◽  
Vol 14 (1-3) ◽  
pp. 155-160 ◽  
Author(s):  
Tatsuhisa Kato
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Theoretical Analysis ◽  
Room Temperature ◽  
Emission Spectra ◽  
Mirror Image ◽  
Ir Absorption ◽  
Near Ir ◽  
Laser Experiments ◽  
Ir Bands

Absorption spectra are detected for C60− and C602− produced electrolytically in solution at room temperature. Theoretical analysis of the spectrum of C60− by CNDO/S calculations gives an interpretation of the characteristic near-IR bands, the weak visible bands, and the strong bands in the UV region. The emission spectrum of C60− is a mirror image of the near-IR absorption band, and the detection of the emission reconfirms our original assignment of the absorption spectrum. The nature of the spectrum of C602− is characterized by a similar orbital picture to that of C60−. Further laser experiments of significance are proposed.

One-dimensional narrow-band conductors

2021 ◽  
Vol 47 (9) ◽  
pp. 715-739
Author(s):  
L. A. Pastur ◽  
V. V. Slavin ◽  
A. A. Krivchikov
Keyword(s):  
Narrow Band ◽  
One Dimensional

Full-Spectrum k-Distribution Model for Radiation in Gas Based on Multi-Group Methods

2014 ◽  
Vol 1008-1009 ◽  
pp. 839-845
Author(s):  
Yue Zhou ◽  
Qiang Wang ◽  
Hai Yang Hu
Keyword(s):  
Narrow Band ◽  
Wide Band ◽  
Distribution Model ◽  
Full Spectrum ◽  
Distribution Method ◽  
One Dimensional ◽  
Group Methods ◽  
Monotonically Increasing Function ◽  
Homogeneous Media ◽  
Increasing Function

The k-distribution method applied in narrow band and wide band is extended to the full spectrum based on spectroscopic datebase HITEMP, educing the full-spectrum k-distribution model. Absorption coefficents in this model are reordered into a smooth,monotonically increasing function such that the intensity calculations are performed only once for each absorption coefficent value and the resulting computations are immensely more efficent.Accuracy of this model is examined for cases ranging from homogeneous one-dimensional carbon dioxide to inhomogeneous ones with simultaneous variations in temperature. Comparision with line-by-line calculations (LBL) and narrow-band k-distribution (NBK) method as well as wide-band k-distribution (WBK) method shows that the full-spectrum k-distribution model is exact for homogeneous media, although the errors are greater than the other two models. After dividing the absorption coefficients into several groups according to their temperature dependence, the full-spectrum k-distribution model achieves line-by-line accuracy for gases inhomogeneous in temperature, accompanied by lower computational expense as compared to NBK model or WBK model. It is worth noting that a new grouping scheme is provided in this paper.

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