Determination of the Density of States in a-SiC:H from Transient Photoconductivity

1996 ◽  
Vol 420 ◽  
Author(s):  
R. Brüggemann ◽  
C. Maint ◽  
M. Rösch ◽  
D. P. Webb
Keyword(s):  
Density Of States ◽  
Spectroscopic Technique ◽  
Drift Mobility ◽  
Wide Energy Range ◽  
Tail Region ◽  
Hydrogenated Silicon ◽  
Transient Photoconductivity ◽  
Amorphous Hydrogenated Silicon ◽  
Wide Energy ◽  
The Fourier Transform

AbstractIn order to fill the gap of little knowledge about their details, the density of states distributions (DOS) in the upper half of the band gap were determined for a series of wellcharacterised amorphous hydrogenated silicon carbide samples with Tauc gaps between 1.78 and 1.94 eV. A DOS spectroscopic technique, based on the Fourier transform of time-sampled transient photocurrents, allowed the DOS determination on an absolute scale for a wide energy range. The DOS increases in the band tail region with carbon content. It exhibits a minimum at about 0.5 eV which is followed by a defect structure at deeper energies, the density of which also increases with C-content. We find a decreasing time-dependent drift mobility for larger C-content consistent with the lower transit time-determined drift mobility in time-of-flight.

The density of states in the mobility gap of amorphous hydrogenated silicon doped with erbium

2005 ◽  
Vol 39 (3) ◽  
pp. 351-353 ◽  
Author(s):  
A. V. Biryukov ◽  
A. G. Kazanskii ◽  
E. I. Terukov ◽  
K. Yu. Khabarova
Keyword(s):  
Density Of States ◽  
Hydrogenated Silicon ◽  
Amorphous Hydrogenated Silicon ◽  
Silicon Doped ◽  
Mobility Gap

scholarly journals Density of Defect States and Spectra of Defect Absorption in a-Si:H

2019 ◽  
Vol 64 (4) ◽  
pp. 315
Author(s):  
R. G. Ikramov ◽  
M. A. Nuriddinova ◽  
R. M. Jalalov
Keyword(s):  
Absorption Coefficient ◽  
Density Of States ◽  
Spectral Characteristics ◽  
Localized States ◽  
Defect States ◽  
Hydrogenated Silicon ◽  
Principal Role ◽  
Electron Transitions ◽  
Amorphous Hydrogenated Silicon ◽  
Density Of Defect States

Spectral characteristics of the coefficient of defect absorption in amorphous hydrogenated silicon have been studied. The characteristics are determined, by analyzing the electron transitions occurring with the participation of the energy states of dangling bonds. It is shown that the principal role in the formation of the defect absorption coefficient value is played by the electron transitions between defect and non-localized states. It is also shown that the spectral characteristics are mainly determined by the distribution function of the electron density of states in the valence or conduction band. It is found that the maxima in the spectrum of the defect absorption coefficient are observed only if there are pronounced maxima in the density of states at the edges of allowed bands.

Determination of the hydrogen density of states in amorphous hydrogenated silicon

1998 ◽  
Vol 227-230 ◽  
pp. 143-147 ◽  
Author(s):  
W.B Jackson ◽  
A.J Franz ◽  
H.-C Jin ◽  
J.R Abelson ◽  
J.L Gland
Keyword(s):  
Density Of States ◽  
Hydrogenated Silicon ◽  
Hydrogen Density ◽  
Amorphous Hydrogenated Silicon

HIGH FIELD TRANSPORT IN a-Si:H

1993 ◽  
Vol 07 (05) ◽  
pp. 1207-1258 ◽  
Author(s):  
C.E. NEBEL ◽  
R.A. STREET
Keyword(s):  
Electric Field ◽  
High Field ◽  
Nearest Neighbor ◽  
Dispersive Transport ◽  
Ballistic Capture ◽  
Hydrogenated Silicon ◽  
Transient Photoconductivity ◽  
Boron Doped ◽  
Amorphous Hydrogenated Silicon ◽  
Hopping Model

Electric field dependent DC-dark and transient photoconductivity data measured over a broad temperature (10 K ≤T≤300 K ) and field regime (102 V/cm ≤F≤6×105 V/cm ) in phosphorus and boron doped and intrinsic amorphous hydrogenated silicon (a-Si:H) are described. The data demonstrate the strong influence of the electric field on carrier propagation. Enhancements over 6 orders of magnitude in conductivity (σ) are achieved for fields greater than 105 V/cm , which changes a-Si:H films from highly insulating to very conductive at low temperatures. The field dependence is described empirically by a power law a~Fy with y in the range 10≤y≤17. The enhancement and y depend on doping level with significant differences between electron and hole currents. These results are confirmed by transient photoconductivity experiments on intrinsic a-Si:H from which the carrier mobility (μ D ) and the μτ-product are deduced. The drift mobility is enhanced by many orders of magnitude up to values of μ D >10−2 cm 2/ Vs and is identified as parameter which dominates high field transport. The increase in mobility is comparable to the increase in conductivity and shows a time- and thickness dependence indicative of dispersive transport. The data is interpreted introducing a field-enhanced nearest neighbor hopping model which is governed by ballistic capture and field induced re-emission.

Pulsed ruby laser accelerated degradation of amorphous hydrogenated silicon

1993 ◽  
Vol 164-166 ◽  
pp. 235-238 ◽  
Author(s):  
O. Klíma ◽  
O. Štika ◽  
Ho Tha Ha ◽  
S. Fouad Abdel Hamied ◽  
J. Stuchlík ◽  
...  
Keyword(s):  
Ruby Laser ◽  
Hydrogenated Silicon ◽  
Accelerated Degradation ◽  
Amorphous Hydrogenated Silicon

scholarly journals Variety Identification of Orchids Using Fourier Transform Infrared Spectroscopy Combined with Stacked Sparse Auto-Encoder

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2506 ◽  
Author(s):  
Yunfeng Chen ◽  
Yue Chen ◽  
Xuping Feng ◽  
Xufeng Yang ◽  
Jinnuo Zhang ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Principal Component ◽  
Fourier Transform Infrared ◽  
Spectroscopic Technique ◽  
Variety Identification ◽  
Support Vector ◽  
K Nearest Neighbors ◽  
Discriminant Models ◽  
The Fourier Transform ◽  
Better Than

The feasibility of using the fourier transform infrared (FTIR) spectroscopic technique with a stacked sparse auto-encoder (SSAE) to identify orchid varieties was studied. Spectral data of 13 orchids varieties covering the spectral range of 4000–550 cm−1 were acquired to establish discriminant models and to select optimal spectral variables. K nearest neighbors (KNN), support vector machine (SVM), and SSAE models were built using full spectra. The SSAE model performed better than the KNN and SVM models and obtained a classification accuracy 99.4% in the calibration set and 97.9% in the prediction set. Then, three algorithms, principal component analysis loading (PCA-loading), competitive adaptive reweighted sampling (CARS), and stacked sparse auto-encoder guided backward (SSAE-GB), were used to select 39, 300, and 38 optimal wavenumbers, respectively. The KNN and SVM models were built based on optimal wavenumbers. Most of the optimal wavenumbers-based models performed slightly better than the all wavenumbers-based models. The performance of the SSAE-GB was better than the other two from the perspective of the accuracy of the discriminant models and the number of optimal wavenumbers. The results of this study showed that the FTIR spectroscopic technique combined with the SSAE algorithm could be adopted in the identification of the orchid varieties.

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