Transport Measurements in LPCVD Amorphous Silicon Obtained from Disilane.

1986 ◽  
Vol 70 ◽  
Author(s):  
C. Manfredotti ◽  
G. Gervino ◽  
L. Montaldi ◽  
U. Nastasi ◽  
R. Murri ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Amorphous Silicon ◽  
Energy Shift ◽  
State Distribution ◽  
Mobility Edge ◽  
Temperature Conductivity ◽  
Exponential Factor ◽  
Tail State ◽  
A Value

ABSTRACTMeasurements of high temperature conductivity on a-Si:H obtained by LPCVD from Si2H6 at temperatures between 450 and 500 °C indicate clearly a change on the activation energy from 0.9 - 1.0 eV to 0.55 - 0.6 eV around 600 °K.The results are not strongly different from those obtained in GD a- SiH4:however, the coefficent of the energy shift of the mobility edge with temperature is greater by a factor of 2, while the average extension of the tail state distribution at T= 0 °K is roughly a factor 1.5 larger. The main discrepancy concerns the pre-exponential factor, which is one or two orders of magnitude larger, giving a product (NcukT)of the order of 1021 cm-1 s-1. By assuming a conduction mobility two orders of magnitude larger than the maesured Hall mobility one obtains a value for N which is only a factor four times larger than what currently assumed for a-Si:H.

Comments on Electron and Hole Transport in the Band Tail States of Amorphous Silicon at Low Temperatures

1989 ◽  
Vol 149 ◽  
Author(s):  
M. Silver ◽  
W. E. Spear
Keyword(s):  
Amorphous Silicon ◽  
Drift Mobility ◽  
Hole Transport ◽  
Experimental Results ◽  
Exponential Tail ◽  
Band Tail ◽  
State Distribution ◽  
Temperature Drift ◽  
Model Calculations ◽  
Tail State

ABSTRACTRecent experimental results on the low temperature drift mobility in amorphous silicon are examined on the basis of the approach to hopping transport developed by Silver and Bässler. It is shown on general grounds that the main features of the experimental results cannot be explained by a purely exponential tail state distribution, but are consistent with the distribution used by Spear and Cloude (1988) in model calculations.

Hot Working of the ZEK200 Magnesium Alloy

2008 ◽  
Vol 604-605 ◽  
pp. 212-222 ◽  
Author(s):  
S. Spigarelli ◽  
Mohamad El Mehtedi ◽  
P. Ricci
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Magnesium Alloy ◽  
Direct Chill ◽  
Equivalent Strain ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Torsion Testing ◽  
A Value ◽  
Complete Recrystallization

The high temperature workability of the ZEK200 Mg-alloy produced by Direct Chill casting (DC) was investigated by torsion testing between 200 and 450°C. The alloy exhibited a higher strength and a slightly lower equivalent strain to fracture than AZ31 and ZM21 produced by DC. The calculation of the constitutive equation gave a value of the activation energy for high temperature deformation close to 175 kJ/mol, in line with those calculated by following the same procedure in AZ31 and ZM21. Partial or complete recrystallization of the deformed structure was observed at 350 and 400°C respectively. Grain growth occurred after recrystallization in the samples tested at 450°C.

Kinetics of Desulfuration Product Sulphoaluminate Calcium

2010 ◽  
Vol 113-116 ◽  
pp. 1814-1817 ◽  
Author(s):  
Hui Ling Guo ◽  
Jun Lin Xie
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Formation Rate ◽  
Experimental Investigations ◽  
Exponential Factor ◽  
First Order ◽  
First Order Kinetics ◽  
Formation Kinetics ◽  
Competitive Reactions ◽  
Kinetics Of

The formation kinetics of sulphoaluminate calcium was studied by variations of sulfur release with time from SC-132 based on competitive reactions, the generation of sulphoaluminate calcium and the decomposition of CaSO4. Experimental investigations and theoretical derivations show that the formation rate of sulphoaluminate calcium can be described as first-order kinetics at high temperature, and it belongs to the mechanism of random nucleus growth. The apparent activation energy is 456.37 KJ•mol-1 and pre-exponential factor is 1.545×1012.

Metastable Activation in Rapid Thermal Annealed Arsenic Implanted Silicon

1985 ◽  
Vol 52 ◽  
Author(s):  
Avid Kamgar ◽  
F. A. Baiocchi
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Thermal Treatment ◽  
A Value ◽  
High Temperature Short Time ◽  
Defective Layer ◽  
Rate Of Increase ◽  
Time Observation ◽  
Short Time ◽  
First Time

ABSTRACTLow temperature (600–800&C) thermal treatment subsequent to high temperature short time anneal of As implanted Si has resulted in significant clustering of As atoms in Si. Si wafers implanted with As at a variety of doses and energies were subjected to single and multiple thermal anneals using incoherent tungsten radiation. Sheet resistance (R▩ ), and Rutherford backscattering (RBS) and channeling measurements were carried out on the wafers. The metastable behavior observed in the activation of As was attributed to electrical deactivation of As atoms caused by clustering. From the temperature dependence of the rate of increase in R▩ we extracted a value of 1.1 eV for the activation energy of electronic deactivation of As atoms in agreement with the value obtained earlier for the activation of As clustering. We also report, for the first time, observation of a structure in the Si RBS spectrum which represents a defective layer in Si caused by the clustering As atoms.

Kinetic Study on Pyrolysis of Gentamicin Residue

2014 ◽  
Vol 955-959 ◽  
pp. 2803-2808
Author(s):  
Ren Ping Liu ◽  
Rui Yao ◽  
Hui Li
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Thermochemical Conversion ◽  
Pyrolysis Kinetics ◽  
Heating Rates ◽  
Exponential Factor ◽  
Thermogravimetric Analyzer ◽  
Basic Work ◽  
Mechanism Function ◽  
Kinetics Of

Gentamicin bacteria residue contains high organic compound. The technology of thermochemical conversion can effectively solve the problem of bulk gentamicin residue disposal, research on pyrolysis kinetics of the reaction is the basic work for thermochemical conversion . In this paper, Pyrolysis experiments were carried out in a thermogravimetric analyzer under inert conditions and operated at different heating rates (5, 10, 20 K/min).Two different kinetic models, the iso-conversional Ozawa–Flynn–Wall (Ozawa) models and Satava method were applied on TGA data of gentamicin residue to calculate the kinetic parameters including activation energy, pre-exponential factor and Mechanism function. The results showed that: gentamicin bacteria residue lost most weight of it between 100-650 °C , about 74.23% of the whole sample can decompose under high temperature. The pyrolysis function for gentamicin residue should be G(α) =[-ln(1-α)]3.

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 %.

Microscopic Interpretation of Arrhenius Parameters

2018 ◽  
Author(s):  
Niels Engholm Henriksen ◽  
Flemming Yssing Hansen
Keyword(s):  
Activation Energy ◽  
Transition State ◽  
Transition State Theory ◽  
Average Energy ◽  
Zero Point ◽  
State Theory ◽  
Exponential Factor ◽  
Quantum Tunnelling ◽  
Microscopic Interpretation ◽  
The Difference

This chapter reviews the microscopic interpretation of the pre-exponential factor and the activation energy in rate constant expressions of the Arrhenius form. The pre-exponential factor of apparent unimolecular reactions is, roughly, expected to be of the order of a vibrational frequency, whereas the pre-exponential factor of bimolecular reactions, roughly, is related to the number of collisions per unit time and per unit volume. The activation energy of an elementary reaction can be interpreted as the average energy of the molecules that react minus the average energy of the reactants. Specializing to conventional transition-state theory, the activation energy is related to the classical barrier height of the potential energy surface plus the difference in zero-point energies and average internal energies between the activated complex and the reactants. When quantum tunnelling is included in transition-state theory, the activation energy is reduced, compared to the interpretation given in conventional transition-state theory.

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