Time-Resolved Switching Studies in a-Si:H and Related Films

2003 ◽  
Vol 762 ◽  
Author(s):  
P. Stradins ◽  
W. B. Jackson ◽  
H. M. Branz ◽  
J. Hu ◽  
C.L. Perkins ◽  
...  
Keyword(s):  
Local Heating ◽  
Charge Trapping ◽  
Atomic Diffusion ◽  
Latency Time ◽  
Time Resolved ◽  
Wide Bandgap Material ◽  
Precursor Phase ◽  
Two Phases ◽  
Pulse Polarity ◽  
Ag Contact

AbstractSwitching in a-Si:H and a-Si:HNx layers is investigated by pulse current transient and Auger scanning microspectroscopy measurements. Switching in a-Si:H with Ag and Cr contacts exhibits 2 different regimes depending on the voltage pulse polarity. With a positive top Ag contact, switching occurs in nanoseconds after a certain latency time, which depends on voltage exponentially. For a negative Ag contact, there is no latency time provided the voltage exceeds a certain critical value. This might be related to interface effects on contact properties or field-assisted metal diffusion. Scanning Auger element micromaps reveal metallic filaments in the switched films. They contain both Ag and Cr throughout the film thickness. Two phases of the filament formation are suggested – a precursor phase and a post-switching phase characterized by local heating and atomic diffusion. Soft and hard switching are observed in a-Si:HNx films simultaneously and their rates depend strongly on the contact material and applied voltage. Soft switching might be related to the charge trapping in this wide bandgap material.

Formation of Pt decorated Ni–Pt nanocubes through low temperature atomic diffusion – time-resolved elemental analysis of nanoparticle formation

Nanoscale ◽  
2015 ◽  
Vol 7 (21) ◽  
pp. 9927-9934 ◽  
Author(s):  
A. Nagao ◽  
K. Higashimine ◽  
J. L. Cuya Huaman ◽  
T. Iwamoto ◽  
T. Matsumoto ◽  
...  
Keyword(s):  
Low Temperature ◽  
Elemental Analysis ◽  
Diffusion Time ◽  
Atomic Diffusion ◽  
Pt Catalysts ◽  
Time Resolved ◽  
Nanoparticle Formation ◽  
The Core ◽  
Temperature Diffusion

Low temperature diffusion of Pt atoms from the core to the corners and edges of the Ni cube results in the preparation of potential novel cage-structured Pt catalysts.

scholarly journals Time-Resolved Spectroscopic Investigation of Charge Trapping in Carbon Nitrides Photocatalysts for Hydrogen Generation

2017 ◽  
Vol 139 (14) ◽  
pp. 5216-5224 ◽  
Author(s):  
Robert Godin ◽  
Yiou Wang ◽  
Martijn A. Zwijnenburg ◽  
Junwang Tang ◽  
James R. Durrant
Keyword(s):  
Spectroscopic Investigation ◽  
Hydrogen Generation ◽  
Charge Trapping ◽  
Time Resolved ◽  
Carbon Nitrides

Possible physical explanation of the intrinsic Ep,i-“intensity” correlation commonly used to “standardize” GRBs

2016 ◽  
Vol 25 (05) ◽  
pp. 1630014 ◽  
Author(s):  
Filippo Frontera ◽  
Lorenzo Amati ◽  
Ruben Farinelli ◽  
Simone Dichiara ◽  
Cristiano Guidorzi ◽  
...  
Keyword(s):  
Thermal Bath ◽  
Time Resolved ◽  
Peak Energy ◽  
Inverse Compton ◽  
Energy Formula ◽  
Two Phases ◽  
Photospheric Model ◽  
Photospheric Radius ◽  
Prompt Emission ◽  
Broad Energy

It is recognized that very likely the correlation between peak energy [Formula: see text] and bolometric intensity is intrinsic to GRBs. However, its physical origin is still debated. In this paper, we will discuss a possible interpretation of the correlation in the light of a GRB prompt emission spectral model, grbcomp, proposed in [L. Titarchuk, R. Farinelli, F. Frontera and L. Amati, Astrophys. J. 752 (2012) 116]. grbcomp is essentially a photospheric model for the prompt emission of GRBs. Its main ingredients are a thermal bath of soft seed photons and a subrelativistically expanding outflow plasma, consequence of the star explosion. The emerging spectrum is the result of two phases: first, up to the photospheric radius, Comptonization of a subrelativistic electron outflow with thermal bath of soft photons, then, convolution of the Comptonized photons in the first phase with a Green function. The result of this convolution is consistent with different physical processes, in particular Inverse Compton. grbcomp has been successfully tested using a significant sample of GRB time resolved spectra in the broad energy band from 2[Formula: see text]keV to 2[Formula: see text]MeV [F. Frontera, L. Amati, R. Farinelli, S. Dichiara, C. Guidorzi, R. Landi and L. Titarchuk, Astrophys. J. 779 (2013) 175].

scholarly journals Unraveling the varied nature and roles of defects in hybrid halide perovskites with time-resolved photoemission electron microscopy

2021 ◽  
Author(s):  
Sofiia Kosar ◽  
Andrew J. Winchester ◽  
Tiarnan A. S. Doherty ◽  
Stuart Macpherson ◽  
Christopher E. Petoukhoff ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Charge Trapping ◽  
Time Resolved ◽  
Photoemission Electron Microscopy ◽  
Halide Perovskites ◽  
Photoemission Electron

Hybrid halide perovskites are found to contain multiple types of nanoscale defects that play varied roles in charge trapping – from highly detrimental to relatively benign.

The Role and Implications of Bassanite as a Stable Precursor Phase to Gypsum Precipitation

Science ◽  
2012 ◽  
Vol 336 (6077) ◽  
pp. 69-72 ◽  
Author(s):  
A. E. S. Van Driessche ◽  
L. G. Benning ◽  
J. D. Rodriguez-Blanco ◽  
M. Ossorio ◽  
P. Bots ◽  
...  
Keyword(s):  
Self Assembly ◽  
Calcium Sulfate ◽  
Water Desalination ◽  
The Self ◽  
Industrial Processes ◽  
Time Resolved ◽  
Gypsum Precipitation ◽  
Precursor Phase ◽  
Stage Process ◽  
High Resolution Microscopy

Calcium sulfate minerals such as gypsum play important roles in natural and industrial processes, but their precipitation mechanisms remain largely unexplored. We used time-resolved sample quenching and high-resolution microscopy to demonstrate that gypsum forms via a three-stage process: (i) homogeneous precipitation of nanocrystalline hemihydrate bassanite below its predicted solubility, (ii) self-assembly of bassanite into elongated aggregates co-oriented along their c axis, and (iii) transformation into dihydrate gypsum. These findings indicate that a stable nanocrystalline precursor phase can form below its bulk solubility and that in the CaSO4 system, the self-assembly of nanoparticles plays a crucial role. Understanding why bassanite forms prior to gypsum can lead to more efficient anti-scaling strategies for water desalination and may help to explain the persistence of CaSO4 phases in regions of low water activity on Mars.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Electron Channeling Patterns

1977 ◽  
Vol 35 ◽  
pp. 12-13
Author(s):  
David C. Joy
Keyword(s):  
Electron Diffraction ◽  
Incidence Angle ◽  
Photographic Plate ◽  
Diffraction Effect ◽  
Angle Of Incidence ◽  
Bulk Single Crystal ◽  
Time Resolved ◽  
Electron Channeling ◽  
Spatially Resolved ◽  
Large Bulk

Electron channeling patterns (ECP) were first found by Coates (1967) while observing a large bulk, single crystal of silicon in a scanning electron microscope. The geometric pattern visible was shown to be produced as a result of the changes in the angle of incidence, between the beam and the specimen surface normal, which occur when the sample is examined at low magnification (Booker, Shaw, Whelan and Hirsch 1967).A conventional electron diffraction pattern consists of an angularly resolved intensity distribution in space which may be directly viewed on a fluorescent screen or recorded on a photographic plate. An ECP, on the other hand, is produced as the result of changes in the signal collected by a suitable electron detector as the incidence angle is varied. If an integrating detector is used, or if the beam traverses the surface at a fixed angle, then no channeling contrast will be observed. The ECP is thus a time resolved electron diffraction effect. It can therefore be related to spatially resolved diffraction phenomena by an application of the concepts of reciprocity (Cowley 1969).

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