scholarly journals Tunneling-assisted thermalization and recombination of nonequilibrium carriers in localized states: Application to the frequency-resolved drift mobility in amorphous silicon

2001 ◽  
Vol 64 (12) ◽  
Author(s):  
K. Hattori ◽  
T. Hirao ◽  
Y. Musa ◽  
H. Okamoto
Keyword(s):  
Amorphous Silicon ◽  
Drift Mobility ◽  
Localized States ◽  
Nonequilibrium Carriers

Determination of Density of Localized States in Amorphous Silicon Alloys From the Low Field Conductance of Thin N-I-N Diodes

1985 ◽  
Vol 49 ◽  
Author(s):  
Michael Shur ◽  
Michael Hack
Keyword(s):  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Bulk Density ◽  
Density Of States ◽  
Energy Gap ◽  
Localized States ◽  
New Technique ◽  
Silicon Alloys ◽  
Low Field ◽  
Density Of Localized States

AbstractWe describe a new technique to determine the bulk density of localized states in the energy gap of amorphous silicon alloys from the temperature dependence of the low field conductance of n-i-n diodes. This new technique allows us to determine the bulk density of states in the centre of a device, and is very straightforward, involving fewer assumptions than other established techniques. Varying the intrinsic layer thickness allows us to measure the,density of states within approximately 400 meV of midgap.We measured the temperature dependence of the low field conductance of an amorphous silicon alloy n-i-n diode with an intrinsic layer thjckness of 0.45 microns and deduced the density of localised states to be 3xlO16cm−3 eV−1 at approximately 0.5 eV below the bottom of the conduction band. We have also considered the high bias region (the space charge limited current regime) and proposed an interpolation formula which describes the current-voltage characteristics of these structures at all biases and agrees well with our computer simulation based on the solution of the complete system of transport equations.

scholarly journals Modulated photoconductivity study of electron drift mobility in amorphous silicon

2000 ◽  
Vol 87 (6) ◽  
pp. 2901-2909 ◽  
Author(s):  
K. Hattori ◽  
M. Iida ◽  
T. Hirao ◽  
H. Okamoto
Keyword(s):  
Amorphous Silicon ◽  
Drift Mobility ◽  
Electron Drift ◽  
Electron Drift Mobility

Analytical Determination of Generation-Recombination Rate In Amorphous Silicon

1986 ◽  
Vol 70 ◽  
Author(s):  
Jože Furlan ◽  
Slavko Amon
Keyword(s):  
Analytical Solution ◽  
Amorphous Silicon ◽  
Cross Sections ◽  
Recombination Rate ◽  
Exponential Model ◽  
Localized States ◽  
Analytical Determination ◽  
Capture Cross ◽  
Capture Cross Sections

ABSTRACTA general expression for generation-recombination rate in a-Si based on classical SRH theory including different electron and hole capture cross-sections for donor-like and acceptor-like centers inside the mobility gap is derived. Applying appropriate approximations and two-exponential model for localized states distribution two methods of analytical solution are presented and discussed.

Luminescent Amorphous Silicon Layers

1997 ◽  
Vol 486 ◽  
Author(s):  
G. Allan ◽  
C. Delerue ◽  
M. Lannoo
Keyword(s):  
Electronic Structure ◽  
Amorphous Silicon ◽  
Radiative Recombination ◽  
Crystalline Silicon ◽  
Tight Binding ◽  
Blue Shift ◽  
Localized States ◽  
Structure Model ◽  
Radiative Recombination Rate ◽  
Tight Binding Approximation

AbstractThe electronic structure of amorphous silicon layers has been calculated within the empirical tight binding approximation using the Wooten-Winer-Weaire atomic structure model. We predict an important blue shift due to the confinement for layer thickness below 3 nm and we compare with crystalline silicon layers. The radiative recombination rate is enhanced by the disorder and the confinement but remains quite small. The comparison of our results with experimental results shows that the density of defects and localized states in the studied samples must be quite small.

Density of Deep Bandgap States in Amorphous Silicon From the Temperature Dependence of Thin Film Transistor Current

1994 ◽  
Vol 336 ◽  
Author(s):  
T. Globus ◽  
H. C. Slade ◽  
M. Shur ◽  
M. Hack
Keyword(s):  
Thin Film ◽  
Activation Energy ◽  
Amorphous Silicon ◽  
Conduction Band ◽  
Energy Gap ◽  
Localized States ◽  
Flat Band ◽  
Gate Bias ◽  
Density Of Localized States ◽  
Wide Range

ABSTRACTWe have measured the current-voltage characteristics of amorphous silicon thin film transistors (a-Si TFTs) over a wide range of temperatures (20 to 160°C) and determined the activation energy of the channel current as a function of gate bias with emphasis on the leakage current and subthreshold regimes. We propose a new method for estimating the density of localized states (DOS) from the dependence of the derivative of activation energy with respect to gate bias. This differential technique does not require knowledge of the flat-band voltage (VFB) and does not incorporate integration over gate bias. Using this Method, we have characterized the density of localized states with energies in the range 0.15–1.2 eV from the bottom of the conduction band and have found a wide peak in the DOS in the range of 0.8–0.95 eV below the conduction band. We have also observed that the DOS peak in the lower half of the bandgap increases in magnitude and shifts towards the conduction band as a result of thermal and bias stress. We also measured an overall increase in the DOS in the upper half of the energy gap and an additional peak, centered at 0.2 eV below the conduction band, which appear due to the applied stress. These results are in qualitative agreement with the defect pool Model [1,2].

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.

Charge transport through localized states in sputtered amorphous silicon suboxides

2001 ◽  
Vol 666 ◽  
Author(s):  
J.J. van Hapert ◽  
N. Tomozeiu ◽  
E.E. van Faassen ◽  
A.M. Vredenberg ◽  
F.H.P.M. Habraken
Keyword(s):  
Amorphous Silicon ◽  
Defect Density ◽  
Rf Magnetron Sputtering ◽  
Quantitative Information ◽  
Thin Layers ◽  
Localized States ◽  
Variable Range Hopping ◽  
Defect States ◽  
Variable Range ◽  
Spin Resonance

ABSTRACTUsing an RF magnetron sputtering technique, thin layers (∼500 nm) of amorphous silicon suboxides (a-SiOx) were deposited, with oxygen/silicon ratios x ranging from 0 to 1.8. These layers contain a large density (1020−1021 cm−3) of, mostly silicon dangling bond, defect states. The level of conduction decreases several orders of magnitude with increasing x. The temperature dependence of the DC conductivity showed that the variable range hopping conduction mechanism is dominant for all x, over the temperature range 30- 330 K. In this mechanism the extent of localization and density of states around the Fermi level determine the conductance. We conclude that the decrease in conductance with increasing oxygen content must, for a large part, be due to a variation in the localization, since Electron Spin Resonance (ESR) measurements showed no decrease in defect density with increasing x. We performed DC conduction measurements at both low and high electric field strengths, showing phenomena, which are consistently desribed within the variable range hopping (VRH) model. These measurements allow the extraction of quantitative information, concerning both the localization and the density of the states involved in the hopping process.

Wide coulomb gap in localized states of 3d-metals in amorphous silicon

1987 ◽  
Vol 90 (1-3) ◽  
pp. 111-114 ◽  
Author(s):  
A.V. Dvurechenskii ◽  
I.A. Ryazantsev ◽  
A.I. Yakimov ◽  
V.A. Dravin
Keyword(s):  
Amorphous Silicon ◽  
Localized States ◽  
Coulomb Gap ◽  
3D Metals
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