High-resolution Photoinduced Transient Spectroscopy of Defect Centers in Undoped Semi-Insulating 6H-SiC

2008 ◽  
Vol 1069 ◽  
Author(s):  
Pawel Kaminski ◽  
Roman Kozlowski ◽  
Marcin Miczuga ◽  
Michal Pawlowski ◽  
Michal Kozubal ◽  
...  
Keyword(s):  
High Resolution ◽  
Emission Rate ◽  
Thermal Emission ◽  
Charge Compensation ◽  
New Approach ◽  
Defect Centers ◽  
The Laplace Transform ◽  
Temperature Dependences ◽  
Transient Spectroscopy ◽  
Induced Changes

ABSTRACTHigh-resolution photoinduced transient spectroscopy (HRPITS) has been applied to studying defect centers controlling the charge compensation in semi-insulating (SI), vanadium-free, bulk 6H- SiC. The photocurrent relaxation waveforms were digitally recorded in the temperature range of 50 − 750 K and a new approach to extract the parameters of defect centers from the temperature-induced changes in the time constants of the waveforms has been implemented. It is based on a two-dimensional analysis using the numerical inversion of the Laplace transform. As a result, the images of spectral fringes depicting the temperature dependences of the emission rate of charge carriers for defect centers are created. Using the new procedure for the analysis of the photocurrent relaxation waveforms and the new way of the visualization of the thermal emission rate dependences, a number of shallow and deep defect levels ranging from 80 to 1900 meV have been detected. The obtained results indicate that defect structure of undoped SI bulk 6H-SiC is very complex and the material properties are affected by various point defects occupying the hexagonal and quasi-cubic lattice sites.

Compensating defect centres in semi-insulating 6H-SiC

2009 ◽  
Vol 17 (1) ◽  
pp. 1-7 ◽  
Author(s):  
P. Kamiński ◽  
R. Kozłowski ◽  
M. Miczuga ◽  
M. Pawłowski ◽  
M. Kozubal ◽  
...  
Keyword(s):  
Point Defects ◽  
Emission Rate ◽  
Thermal Emission ◽  
Charge Compensation ◽  
Charge Carriers ◽  
Two Dimensional ◽  
New Approach ◽  
Temperature Dependences ◽  
Transient Spectroscopy ◽  
Defect Centres

AbstractPhotoinduced transient spectroscopy (PITS) has been applied to study electronic properties of point defects associated with charge compensation in semi-insulating (SI) 6H-SiC substrates. The photocurrent relaxation waveforms were digitally recorded in a wide temperature range of 20–800 K and in order to extract the parameters of defect centres, a two-dimensional analysis of the waveforms as a function of time and temperature has been implemented. As a result, the processes of thermal emission of charge carriers from defect centres were seen on the spectral surface as the folds, whose ridgelines depicted the temperature dependences of emission rate for detected defect centres. The new approach was used to compare the defect levels in vanadium-doped and vanadium-free (undoped) SI 6H-SiC wafers.

Application of Computational Intelligence to Investigation of Defect Centers in Semi-Insulating Materials by Photoinduced Transient Spectroscopy

2007 ◽  
Vol 994 ◽  
Author(s):  
Pawel Kaminski ◽  
Stanislaw Jankowski ◽  
Roman Kozlowski ◽  
Janusz Bedkowski
Keyword(s):  
Computational Intelligence ◽  
Emission Rate ◽  
Thermal Emission ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Inverse Laplace Transform ◽  
Model Complexity ◽  
Support Vector ◽  
Defect Centers ◽  
Temperature Dependences

AbstractA computational intelligence algorithm has been applied to extracting trap parameters from the photocurrent relaxation waveforms recorded at the temperature range of 20-320 K for semi-insulating (SI) InP samples. Using the inverse Laplace transform procedure, the spectral surfaces, visualized in the three dimensional space as functions of temperature and emission rate, are calculated. The processes of thermal emission of charge carriers from defect centers manifest themselves as the sharp folds on the spectral surface. Using a set of Gaussian functions, the approximating surface is created and the ridgelines of the folds, giving the temperature dependences of the emission rate for the detected traps, are determined. The approximation is performed using the support vector machine (SVM) algorithm which allows for trading off between the model complexity and fitting accuracy. The new approach is exemplified by comparing the defect structure of SI InP wafers after annealing in iron phosphide and pure phosphorous atmospheres.

High-resolution photoinduced transient spectroscopy of defect centers in vanadium-doped semi-insulating SiC

2008 ◽  
Vol 19 (S1) ◽  
pp. 224-228 ◽  
Author(s):  
Paweł Kamiński ◽  
Roman Kozłowski ◽  
Marcin Miczuga ◽  
Michał Pawłowski ◽  
Michał Kozubal ◽  
...  
Keyword(s):  
High Resolution ◽  
Defect Centers ◽  
Transient Spectroscopy

Non-Contact, No Wafer Preparation Deep Level Transient Spectroscopy (DlTS) Based on Surface Photovoltage (SPV)

1992 ◽  
Vol 261 ◽  
Author(s):  
Jacek Lagowski ◽  
Piotr Edelman ◽  
Mark Dexter
Keyword(s):  
Emission Rate ◽  
Thermal Emission ◽  
Deep Level ◽  
Surface States ◽  
Deep Level Defect ◽  
Recombination Lifetime ◽  
Experimental Implementation ◽  
Transient Spectroscopy ◽  
Rate Window ◽  
Minority Carriers

ABSTRACTThis work reports on the theoretical modeling and experimental investigation of isothermal SPV-DLTS based on the rate window concept. Experimental implementation of the technique is done using computer analysis of the SPV transients after ceasing the illumination. The transient involves two processes – a recombination of excess minority carriers and a thermal emission of carriers trapped by surface states and bulk defects. The later process is the key one for deep level defect determination.The upper limit for the measurable deep level emission rate is provided by the recombination lifetime. This limit often exceeds, by orders of magnitude, the standard 103 s−1 limit in capacitance DLTS. The sensitivity of SPV-DLTS is of the same order as that of optical capacitance DLTS.

Tailoring the Electrical Properties of Undoped GaP

2011 ◽  
Vol 178-179 ◽  
pp. 410-415 ◽  
Author(s):  
Pawel Kaminski ◽  
Roman Kozlowski ◽  
Stanislawa Strzelecka ◽  
Andrzej Hruban ◽  
Elzbieta Jurkiewicz-Wegner ◽  
...  
Keyword(s):  
Deep Level ◽  
Experimental Studies ◽  
Charge Compensation ◽  
Shallow Donor ◽  
Residual Concentration ◽  
Charge Neutrality ◽  
Shallow Acceptor ◽  
Acceptor Concentration ◽  
Defect Centers ◽  
Transient Spectroscopy

The charge compensation in undoped GaP single crystals is investigated by modeling the Fermi level position for various concentrations of shallow and deep donors and acceptors. The model is based on the numerical solution of the charge neutrality equation and allows for calculating the Fermi energy in the temperature range of 1 –1000 K. The experimental studies of the electronic properties and concentrations of grown-in defect centers are performed by the high-resolution photoinduced transient spectroscopy (HRPITS). We show that at the shallow acceptor concentration below 1x1015 cm-3 and the concentration of deep-level defects ~3x1015 cm-3 obtaining undoped GaP with the semi-insulating (SI) properties is possible by substantial reducing the residual concentration of shallow donor impurities.

scholarly journals High-resolution neutron imaging: a new approach to characterize water in anodic aluminum oxides

2020 ◽  
Vol 8 ◽  
pp. 100121
Author(s):  
Noémie Ott ◽  
Claudia Cancellieri ◽  
Pavel Trtik ◽  
Patrik Schmutz
Keyword(s):  
High Resolution ◽  
Neutron Imaging ◽  
Aluminum Oxides ◽  
New Approach ◽  
Anodic Aluminum

Point Defects in 4H-SiC Epilayers Introduced by 4.5 MeV Electron Irradiation and their Effect on Power JBS SiC Diode Characteristics

2013 ◽  
Vol 205-206 ◽  
pp. 451-456 ◽  
Author(s):  
Pavel Hazdra ◽  
Vít Záhlava ◽  
Jan Vobecký
Keyword(s):  
Electron Irradiation ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Radiation Defects ◽  
Electrical Parameters ◽  
Power Diodes ◽  
Defect Centers ◽  
Measurement Results ◽  
Transient Spectroscopy ◽  
State Resistance

Electronic properties of radiation damage produced in 4H-SiC by electron irradiation and its effect on electrical parameters of Junction Barrier Schottky (JBS) diodes were investigated. 4H‑SiC N‑epilayers, which formed the low‑doped N-base of JBS power diodes, were irradiated with 4.5 MeV electrons with fluences ranging from 1.5x1014 to 5x1015 cm-2. Radiation defects were then characterized by capacitance deep-level transient spectroscopy and C-V measurement. Results show that electron irradiation introduces two defect centers giving rise to acceptor levels at EC‑0.39 and EC‑0.60 eV. Introduction rate of these centers is 0.24 and 0.65 cm‑1, respectively. These radiation defects have a negligible effect on blocking and dynamic characteristics of irradiated diodes, however, the acceptor character of introduced deep levels and their high introduction rates deteriorate diode’s ON-state resistance already at fluences higher than 1x1015 cm‑2.

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