scholarly journals Ultra-slow dynamic annealing of neutron-induced defects in n-type silicon: role of charge carriers

2020 ◽  
Vol 135 (10) ◽  
Author(s):  
Ying Zhang ◽  
Yang Liu ◽  
Hang Zhou ◽  
Ping Yang ◽  
Jie Zhao ◽  
...  
Keyword(s):  
Charge Carriers ◽  
Slow Dynamic ◽  
Type Silicon ◽  
Induced Defects

Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

1993 ◽  
Vol 58 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
Abd El-Aziz A. Said
Keyword(s):  
Active Sites ◽  
Isopropyl Alcohol ◽  
Oxide Catalyst ◽  
Flow System ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

scholarly journals WHY SCREENING EFFECTS DO NOT INFLUENCE THE CASIMIR FORCE

2009 ◽  
Vol 24 (08n09) ◽  
pp. 1721-1742 ◽  
Author(s):  
V. M. MOSTEPANENKO ◽  
R. S. DECCA ◽  
E. FISCHBACH ◽  
B. GEYER ◽  
G. L. KLIMCHITSKAYA ◽  
...  
Keyword(s):  
Casimir Force ◽  
Charge Carriers ◽  
Reflection Coefficients ◽  
Dispersion Forces ◽  
Physical Reason ◽  
Lifshitz Theory ◽  
Third Law Of Thermodynamics ◽  
Applicability Condition ◽  
And Diffusion

The Lifshitz theory of dispersion forces leads to thermodynamic and experimental inconsistencies when the role of drifting charge carriers is included in the model of the dielectric response. Recently modified reflection coefficients were suggested that take into account screening effects and diffusion currents. We demonstrate that this theoretical approach leads to a violation of the third law of thermodynamics (Nernst's heat theorem) for a wide class of materials and is excluded by the data from two recent experiments. The physical reason for its failure is explained by the violation of thermal equilibrium, which is the fundamental applicability condition of the Lifshitz theory, in the presence of drift and diffusion currents.

scholarly journals Peculiarities of time-dependent-dielectric breakdown characteristics of pure and doped Ta2O5 stacks

2013 ◽  
Vol 26 (3) ◽  
pp. 281-296
Author(s):  
E. Atanassova ◽  
A. Paskaleva
Keyword(s):  
Dielectric Breakdown ◽  
Interface Layer ◽  
Time Dependent ◽  
Relative Impact ◽  
Time Dependent Dielectric Breakdown ◽  
Breakdown Mechanism ◽  
Number Of Factors ◽  
High K ◽  
Induced Defects

The effect of both the process-induced defects and the dopant on the time-dependent-dielectric breakdown in Ta2O5 stacks is discussed. The breakdown degradation is analyzed in terms of specific properties of high-k stacks which make their dielectric breakdown mechanism completely different from that of classical SiO2. The relative impact of a number of factors constituting the reliability issues in Ta2O5-based capacitors (trapping in pre-existing traps, stress-induced new traps generation, the presence of interface layer at Si and the role of the dopant) is clarified.

Review of the Synthetic Chemistry Involved in the Production of Core/Shell Semiconductor Nanocrystals

2007 ◽  
Vol 60 (7) ◽  
pp. 457 ◽  
Author(s):  
Joel van Embden ◽  
Jacek Jasieniak ◽  
Daniel E. Gómez ◽  
Paul Mulvaney ◽  
Michael Giersig
Keyword(s):  
Semiconductor Nanocrystals ◽  
Critical Role ◽  
Charge Carriers ◽  
Core Shell ◽  
Synthetic Chemistry ◽  
Shell Material ◽  
Growth Processes ◽  
Passivating Layer ◽  
Spectral Shifts

Passivation of CdSe semiconductor nanocrystals can be achieved by overcoating the particles with a homogeneous shell of a second semiconductor. Shell layers are grown in monolayer steps to ensure homogeneous growth of the shell. The relative band edges of the two materials determine the photoreactiveity of the resultant core-shell nanocrystals. The critical role of ligands in minimizing nucleation of the shell material during the growth of the passivating layer is emphasized. The delocalization of charge carriers into the shell layers can be followed spectroscopically during the growth processes. The relative spectral shifts are directly correlated to the relative energies of the band edges.

Revisiting the chevrel phase: Impact of dispersion corrections on the properties of Mo6S8 for cathode applications

2021 ◽  
Author(s):  
Katharina Helmbrecht ◽  
Holger Euchner ◽  
Axel Gross
Keyword(s):  
Cathode Material ◽  
Diffusion Mechanism ◽  
Charge Carrier Mobility ◽  
Charge Carriers ◽  
Dispersion Forces ◽  
Chevrel Phase ◽  
Connected Cluster ◽  
Ion Size ◽  
The Impact

While the Mo6S8 chevrel phase is frequently used as cathode material in Mg--ion batteries, theoretical studies on this material are comparatively scarce. The particular structure of the Mo6S8 phase, with rather loosely connected cluster entities, points to the important role of dispersion forces in this material. However, so far this aspect has been completely neglected in the discussion of Mo6S8 as cathode material for mono- and multivalent-ion batteries. In this work we therefore have studied the impact of dispersion forces on stability and kinetics of Mo6S8 intercalation compounds. For this purpose, a series of charge carriers (Li, Na, K, Mg, Ca, Zn, Al) has been investigated. Interestingly, dispersion forces are observed to only slightly affect the lattice spacing of the chevrel phase, nevertheless having a significant impact on insertion voltage and in particular on the charge carrier mobility in the material. Moreover, upon varying the charge carriers in the chevrel phase, their diffusion barriers are observed to scale linearly with the ion size, almost independent of the charge of the considered ions. This indicates a rather unique and geometry dominated diffusion mechanism in the chevrel phase. The consequences of these findings for the ion mobility in the chevrel phase will be carefully discussed.

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