Carrier Transport Through Grain Boundaries in Hydrogenated Microcrystalline Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
S. Grebner ◽  
F. Wang ◽  
R. Schwarz
Keyword(s):  
Activation Energy ◽  
Grain Boundaries ◽  
Carrier Transport ◽  
Structural Information ◽  
Dark Conductivity ◽  
Microcrystalline Silicon ◽  
X Ray ◽  
Fermi Level Pinning ◽  
X Ray Scattering ◽  
Three Phase

ABSTRACTTo analyse the influence of the grain boundaries (gb) on the transport of carriers in hydrogenated microcrystalline silicon (μC-Si:H) the ambipolar diffusion length (LLMB) was measured by SSPG. In addition, the films were characterised by photo-conductivity, dark conductivity activation energy, Urbach energy (determined by CPM), hydrogen effusion, Raman spectroscopy, X-ray scattering and optical transmission.The sample series was prepared by PECVD of SiH4 diluted with increasing H2 content. Taking the structural information by Raman spectra and X-ray into account, we explain our optical and activation energy measurements within a three-phase-model (amorphous phase, crystalline phase, gb) and a Fermi level pinning in μc-Si:H.

The Meyer-Neldel Rule in Conductivity of Microcrystalline Silicon

2002 ◽  
Vol 715 ◽  
Author(s):  
Sanjay K. Ram ◽  
Satyendra Kumar ◽  
P. Rocai Cabarrocas
Keyword(s):  
Activation Energy ◽  
Grain Boundary ◽  
Film Thickness ◽  
Fermi Level ◽  
Carrier Transport ◽  
Dark Conductivity ◽  
Localized States ◽  
Microcrystalline Silicon ◽  
Thermally Activated ◽  
Density Of Localized States

AbstractThe dark conductivity (σd) has been measured from 300 to 440K on undoped hydrogenated microcrystalline silicon (μc-Si:H) films having different thicknesses. The carrier transport is found to be thermally activated with single activation energy (Ea) in all the samples. The Ea increases as the film thickness decreases. At the same time logarithmic of dark conductivity prefactor (σo) is found to follow a linear relation with activation energy, known as the Meyer-Neldel rule (MNR). Results are explained in terms of increased degree of disorder in thinner samples. Thus change in Ea with the film thickness is directly related to the density of localized states at the Fermi level in grain boundary (GB). Therefore varying the film thickness and, hence, the exponential density of states induces a statistical shift of Fermi level which gives rise to the observed MNR.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

scholarly journals SAXS Merge: an automated statistical method to merge SAXS profiles using Gaussian processes

2013 ◽  
Vol 21 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Yannick G. Spill ◽  
Seung Joong Kim ◽  
Dina Schneidman-Duhovny ◽  
Daniel Russel ◽  
Ben Webb ◽  
...  
Keyword(s):  
Statistical Method ◽  
High Throughput ◽  
Gaussian Processes ◽  
Small Angle ◽  
Structural Information ◽  
Linear Interpolation ◽  
High Quality ◽  
X Ray ◽  
X Ray Scattering ◽  
Specific Order

Small-angle X-ray scattering (SAXS) is an experimental technique that allows structural information on biomolecules in solution to be gathered. High-quality SAXS profiles have typically been obtained by manual merging of scattering profiles from different concentrations and exposure times. This procedure is very subjective and results vary from user to user. Up to now, no robust automatic procedure has been published to perform this step, preventing the application of SAXS to high-throughput projects. Here,SAXS Merge, a fully automated statistical method for merging SAXS profiles using Gaussian processes, is presented. This method requires only the buffer-subtracted SAXS profiles in a specific order. At the heart of its formulation is non-linear interpolation using Gaussian processes, which provides a statement of the problem that accounts for correlation in the data.

scholarly journals Structure and oligomerization state of the C-terminal region of the Middle East respiratory syndrome coronavirus nucleoprotein

2019 ◽  
Vol 75 (1) ◽  
pp. 8-15 ◽  
Author(s):  
Thi Hong Van Nguyen ◽  
Julie Lichière ◽  
Bruno Canard ◽  
Nicolas Papageorgiou ◽  
Sarah Attoumani ◽  
...  
Keyword(s):  
Middle East ◽  
Structural Information ◽  
Respiratory Illness ◽  
Middle East Respiratory Syndrome ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Nucleoprotein N ◽  
High Degree ◽  
Genome Encapsidation

Middle East respiratory syndrome coronavirus (MERS-CoV) is a human pathogen responsible for a severe respiratory illness that emerged in 2012. Structural information about the proteins that constitute the viral particle is scarce. In order to contribute to a better understanding of the nucleoprotein (N) in charge of RNA genome encapsidation, the structure of the C-terminal domain of N from MERS-CoV obtained using single-crystal X-ray diffraction is reported here at 1.97 Å resolution. The molecule is present as a dimer in the crystal structure and this oligomerization state is confirmed in solution, as measured by additional methods including small-angle X-ray scattering measurements. Comparisons with the structures of the C-terminal domains of N from other coronaviruses reveals a high degree of structural conservation despite low sequence conservation, and differences in electrostatic potential at the surface of the protein.

scholarly journals 20 YEARS OF LEPTIN: Insights into signaling assemblies of the leptin receptor

2014 ◽  
Vol 223 (1) ◽  
pp. T9-T23 ◽  
Author(s):  
Frank Peelman ◽  
Lennart Zabeau ◽  
Kedar Moharana ◽  
Savvas N Savvides ◽  
Jan Tavernier
Keyword(s):  
Electron Microscopy ◽  
Energy Homeostasis ◽  
Leptin Receptor ◽  
Structural Information ◽  
Cell Types ◽  
Activation Mechanism ◽  
Peripheral Cell ◽  
X Ray ◽  
X Ray Crystallography ◽  
X Ray Scattering

Leptin plays a central role in the control of body weight and energy homeostasis, but is a pleiotropic cytokine with activities on many peripheral cell types. In this review, we discuss the interaction of leptin with its receptor, and focus on the structural and mechanistic aspects of the extracellular aspects of leptin receptor (LR) activation. We provide an extensive overview of all structural information that has been obtained for leptin and its receptor via X-ray crystallography, electron microscopy, small-angle X-ray scattering, homology modeling, and mutagenesis studies. The available knowledge is integrated into putative models toward a recapitulation of the LR activation mechanism.

scholarly journals X-Ray Cross-Correlation Analysis of Disordered Ensembles of Particles: Potentials and Limitations

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
R. P. Kurta ◽  
M. Altarelli ◽  
I. A. Vartanyants
Keyword(s):  
Correlation Analysis ◽  
Disordered Systems ◽  
Cross Correlation ◽  
Structural Information ◽  
Three Dimensional ◽  
X Ray ◽  
X Ray Scattering ◽  
Cross Correlation Analysis ◽  
2D And 3D ◽  
Ray Scattering

Angular X-ray cross-correlation analysis (XCCA) is an approach to study the structure of disordered systems using the results of X-ray scattering experiments. In this paper we summarize recent theoretical developments related to the Fourier analysis of the cross-correlation functions. Results of our simulations demonstrate the application of XCCA to two- and three-dimensional (2D and 3D) disordered ensembles of particles. We show that the structure of a single particle can be recovered using X-ray data collected from a 2D disordered system of identical particles. We also demonstrate that valuable structural information about the local structure of 3D systems, inaccessible from a standard small-angle X-ray scattering experiment, can be resolved using XCCA.

Anomalous X-ray Scattering for Determination of Nanostructured Alloy Formation and Site-specific Chemistry of Bragg Peak

2002 ◽  
Vol 740 ◽  
Author(s):  
G.M. Chow
Keyword(s):  
Grain Boundaries ◽  
Volume Ratio ◽  
Alloy Formation ◽  
Nanostructured Films ◽  
X Ray ◽  
Surface And Interface ◽  
X Ray Scattering ◽  
Interphase Interface ◽  
Composition Structure ◽  
Ray Scattering

ABSTRACTThe properties of nanostructured films can be tailored by many factors such as composition, structure, preferred orientation, microstructure, interphase interface and grain boundaries. Compositional control of magnetic properties of recording media depends on the miscibility of constituent elements. However, for nanostructured materials with a large surface-to-volume ratio of atoms, the miscibility at the nanoscale may not necessarily follow the prediction of conventional phase diagram that does not consider the effects of surface and interface. This limitation further complicates the prediction of phase separation at grain boundaries and interphase interface. Using anomalous x-ray scattering, the alloying and composition of a specific long range order of textured nanostructured films has been investigated. Such information may not be readily available from conventional characterization techniques.

Determination of activation energy for crystallization in metallic glass by small angle X-ray scattering

1992 ◽  
Vol 144 ◽  
pp. 308-311
Author(s):  
Chaofu Meng ◽  
Shong-yan Chen ◽  
Ming-yong Qiao ◽  
Zhen-jie Shao
Keyword(s):  
Activation Energy ◽  
Metallic Glass ◽  
Small Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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