The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Chihaya Adachi - One of the best experts on this subject based on the ideXlab platform.
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degradation mechanisms of solution processed planar perovskite solar cells Thermally Stimulated Current measurement for analysis of carrier traps
Advanced Materials, 2016Co-Authors: Toshinori Matsushima, Takashi Fujihara, William J Potscavage, Chihaya AdachiAbstract:: Degradation mechanisms of CH3 NH3 PbI3 -based planar perovskite solar cells (PSCs) are investigated using a Thermally Stimulated Current technique. Hole traps lying above the valence-band edge of the CH3 NH3 PbI3 are detected in PSCs degraded by continuous simulated solar illumination. One source of the hole traps is the photodegradation of CH3 NH3 PbI3 in the presence of water.
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evaluating carrier accumulation in degraded bulk heterojunction organic solar cells by a Thermally Stimulated Current technique
Advanced Functional Materials, 2009Co-Authors: Kenji Kawano, Chihaya AdachiAbstract:Here, the initial photo-degradation of encapsulated P3HT:PCBM bulk heterojunction organic solar cells is investigated. The degraded device is recovered by thermal annealing treatment. Thermally Stimulated Current measurements reveal that the cause of photo-degradation is carrier accumulation and that the degraded organic solar cell has two broad trap levels, of 0.71 and 0.81 eV. These traps are independent of the thickness of the photoactive layers, the mixing ratio of the photoactive materials and the cathode materials. In addition, it is confirmed that there is a close relationship between the degree of degradation and the amount of accumulated charge carriers.
H Ozkan - One of the best experts on this subject based on the ideXlab platform.
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estimation of Thermally Stimulated Current in as grown tlgases layered single crystals by multilayered perceptron neural network
Expert Systems With Applications, 2011Co-Authors: Ilker Kucuk, Tacettin Yildirim, N M Gasanly, H OzkanAbstract:Research highlights? Thermally Stimulated Current estimation in TlGaSeS layered single crystal. ? The model is fast and more accurately and easily estimated the TSC in TlGaSeS. ? The ANN approach can be useful tool for researcher to assess the traps distribution. This paper presents an artificial neural network approach to compute Thermally Stimulated Current (TSC) in as-grown TlGaSeS layered single crystals. The experimental data have been obtained from TSC measurements. The network has been trained by a genetic algorithm (GA). The results confirmed that the proposed model could provide an accurate computation of the TSC.
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determination of trapping center parameters of tl2ingas4 layered crystals by Thermally Stimulated Current measurements
Journal of Alloys and Compounds, 2006Co-Authors: Nader A P Mogaddam, N M Gasanly, N S Yuksek, H OzkanAbstract:Abstract We have carried out Thermally Stimulated Current measurements on as-grown Tl 2 InGaS 4 -layered single crystals in the low temperature range 10–60 K with different heating rates. We found experimental evidence for the presence of two shallow hole trapping centers with activation energies of 4 and 10 meV. We have determined the trap parameters using various methods of analysis, and these agree with each other. Their capture cross-sections have been found to be 6.5 × 10 −26 and 4.0 × 10 −25 cm 2 , respectively, and their concentrations are 2.1 × 10 12 and 6.5 × 10 12 cm −3 , respectively. It is concluded that in these centers retrapping is negligible, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.
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Thermally Stimulated Current analysis of shallow levels in tlgas2 layered single crystals
Semiconductor Science and Technology, 2003Co-Authors: N S Yuksek, N M Gasanly, H OzkanAbstract:We have carried out Thermally Stimulated Current measurements on as-grown TlGaS2 layered single crystals in the temperature range of 10–60 K with various heating rates. We found experimental evidence for the presence of three trapping centres in TlGaS2, located at 6, 12 and 26 meV. We have determined the trap parameters using various methods of analysis, and these agree well with each other. The retrapping process is negligible for these levels, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.
N M Gasanly - One of the best experts on this subject based on the ideXlab platform.
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estimation of Thermally Stimulated Current in as grown tlgases layered single crystals by multilayered perceptron neural network
Expert Systems With Applications, 2011Co-Authors: Ilker Kucuk, Tacettin Yildirim, N M Gasanly, H OzkanAbstract:Research highlights? Thermally Stimulated Current estimation in TlGaSeS layered single crystal. ? The model is fast and more accurately and easily estimated the TSC in TlGaSeS. ? The ANN approach can be useful tool for researcher to assess the traps distribution. This paper presents an artificial neural network approach to compute Thermally Stimulated Current (TSC) in as-grown TlGaSeS layered single crystals. The experimental data have been obtained from TSC measurements. The network has been trained by a genetic algorithm (GA). The results confirmed that the proposed model could provide an accurate computation of the TSC.
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Thermally Stimulated Current measurements in as grown tlgases layered single crystals
Current Applied Physics, 2009Co-Authors: Tacettin Yildirim, N M GasanlyAbstract:Abstract Charge carrier traps in as-grown TlGaSeS layered single crystals were studied using Thermally Stimulated Current measurements. The investigations were performed in temperatures ranging from 10 to 100 K. The experimental evidences were found for the presence of one shallow hole trapping center in TlGaSeS, located at 12 meV from the valence band. The trap parameters have been calculated using various methods of analysis, and these agree well with each other. Its capture cross-section and concentration have been found to be 8.9 × 10 −26 cm 2 and 2.0 × 10 14 cm −3 , respectively. Analysis of the Thermally Stimulated Current data at different light excitation temperatures leads to a value of 19 meV/decade for the shallow hole traps distribution.
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Determination of trapping center parameters in Tl2In2S3Se layered single crystals by Thermally Stimulated Current measurements
Physica B-condensed Matter, 2009Co-Authors: I. Guler, N M GasanlyAbstract:Abstract As-grown Tl2In2S3Se layered single crystals were studied by Thermally Stimulated Current measurements in the temperature range of 10–170 K with different heating rates. Experimental data were analyzed according to various methods such as curve fitting and initial rise. The analysis of Thermally Stimulated Current spectra registered at light excitation temperature T0=10 K revealed the trap level located at 30 meV. Attempt-to-escape frequency, concentration and capture cross section of the traps were determined as 4.2 s−1, 2.4×109 cm−3 and 1.7×10−24 cm2, respectively. It was concluded that slow retrapping (monomolecular condition) occurs for the traps in Tl2In2S3Se crystals. By the analysis of Thermally Stimulated Current data at different light excitation temperatures, the value of 39 meV/decade was obtained for traps distribution.
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determination of trapping center parameters of tl2ingas4 layered crystals by Thermally Stimulated Current measurements
Journal of Alloys and Compounds, 2006Co-Authors: Nader A P Mogaddam, N M Gasanly, N S Yuksek, H OzkanAbstract:Abstract We have carried out Thermally Stimulated Current measurements on as-grown Tl 2 InGaS 4 -layered single crystals in the low temperature range 10–60 K with different heating rates. We found experimental evidence for the presence of two shallow hole trapping centers with activation energies of 4 and 10 meV. We have determined the trap parameters using various methods of analysis, and these agree with each other. Their capture cross-sections have been found to be 6.5 × 10 −26 and 4.0 × 10 −25 cm 2 , respectively, and their concentrations are 2.1 × 10 12 and 6.5 × 10 12 cm −3 , respectively. It is concluded that in these centers retrapping is negligible, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.
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Thermally Stimulated Current analysis of shallow levels in tlgas2 layered single crystals
Semiconductor Science and Technology, 2003Co-Authors: N S Yuksek, N M Gasanly, H OzkanAbstract:We have carried out Thermally Stimulated Current measurements on as-grown TlGaS2 layered single crystals in the temperature range of 10–60 K with various heating rates. We found experimental evidence for the presence of three trapping centres in TlGaS2, located at 6, 12 and 26 meV. We have determined the trap parameters using various methods of analysis, and these agree well with each other. The retrapping process is negligible for these levels, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.
Colette Lacabanne - One of the best experts on this subject based on the ideXlab platform.
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Thermally Stimulated Current spectroscopy of amorphous and semi-crystalline polymers
Journal of Thermal Analysis and Calorimetry, 1999Co-Authors: C. Bacharan, A. Bernes, C. Dessaux, Colette LacabanneAbstract:Thermally Stimulated Current (TSC) spectrometry has been applied to the characterization of polymeric materials. The study of a series of amorphous polymers having different physical structures has shown that the compensation parameters are independent of physical aging; contrarily, the activation enthalpy distribution reflects the evolution of the heterogeneity of the amorphous phase.
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Thermally Stimulated Current Spectroscopy of Amorphous and Semi-Crystalline Polymers
Journal of Thermal Analysis and Calorimetry, 1999Co-Authors: C. Bacharan, A. Bernes, C. Dessaux, Colette LacabanneAbstract:Thermally Stimulated Current (TSC) spectrometry has been applied to the characterization of polymeric materials. The study of a series of amorphous polymers having different physical structures has shown that the compensation parameters are independent of physical aging; contrarily, the activation enthalpy distribution reflects the evolution of the heterogeneity of the amorphous phase. In copolymers, TSC allows us to identify segregated amorphous phases. In semi-crystalline polymers, with semi-rigid chains, we have shown the existence of an amorphous crystalline interphase characterized by a plateau in the temperature distribution of activation enthalpy.
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Thermally Stimulated Current changes of irradiated skin
Journal of Materials Science: Materials in Medicine, 1996Co-Authors: S. Mezghani, A. Lamure, Dan L. Bader, Colette LacabanneAbstract:Radiation effects on collagen and skin have been characterized by means of Thermally Stimulated Current (TSC) spectroscopy. X-rays, β-rays and UV radiation have similar effects on the molecular mobility of dermal collagen and skin. They induce a decrease of intra and intermolecular mobility. The restriction of molecular movement can be explained by an increase of collagen cross-links.
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Study by Thermally Stimulated Current spectroscopy of radiation damage to skin
Proceedings of 8th International Symposium on Electrets (ISE 8), 1994Co-Authors: S. Mezghani, A. Lamure, Colette LacabanneAbstract:The purpose of this study is to characterize the effects of radiation on collagen and skin by Thermally Stimulated Current (TSC) spectroscopy. X-rays, /spl beta/-rays and UV radiation have similar effects on the molecular mobility of dermal collagen and skin. They induce the decrease of magnitude of the intra and intermolecular mobilities. The restriction of the molecular movements can be explained by an increase of collagen cross links.
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Transitions of crystalline 1,3,5-trichloro-2,4,6-trimethylbenzene by Thermally Stimulated Current
Proceedings of 8th International Symposium on Electrets (ISE 8), 1994Co-Authors: A. Bennis, A. Lamure, N. Hitmi, Colette LacabanneAbstract:The present paper reports the results of Thermally Stimulated Current TSC spectroscopy on 1,3,5-trichloro-2,4,6-trimethylbenzene (TCTMB). We have investigated the relaxation phenomena between liquid nitrogen temperature and 80/spl deg/C covering the two stable solid phases III and IV. The phase behaviour of TCTMB is very complicated because the phase transitions are dependent both on temperature and on time in addition to the thermal history of the specimen. A series of TSC complex spectra corresponding to different thermal history has been performed. Results are discussed in relation to the corresponding structure as determined by X-ray diffraction and are compared with differential scanning calorimetry data reported in the literature.
Z.-q. Fang - One of the best experts on this subject based on the ideXlab platform.
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Thermally Stimulated Current spectroscopy of high-purity semi-insulating 4H-SiC substrates
Journal of Electronic Materials, 2005Co-Authors: Z.-q. Fang, D.c. Look, B. Claflin, L. Polenta, W. C. MitchelAbstract:High-purity semi-insulating (HPSI) 4H-SiC has been widely used as a substrate material for AlGaN/GaN high electron-mobility transistors because of its fairly good lattice match with GaN and its high thermal conductivity. To control material quality, it is important to understand the nature of the deep traps. For this purpose, we have successfully applied Thermally Stimulated Current (TSC) spectroscopy to investigate deep traps in two HPSI 4H-SiC samples grown by physical vapor transport (PVT) and high-temperature chemical vapor deposition (HTCVD), respectively. Fundamentals of TSC spectroscopy, typical TSC spectra obtained on the two samples, and theoretical fittings of a boron-related trap (peaked at ∼ 150 K) will be presented. Based on literature data for deep traps in conductive 4H-SiC, the impurity and point-defect nature of several commonly observed TSC traps, peaked at ∼105 K (0.22 eV), ∼150 K (0.29 eV), ∼175 K (∼0.33 eV), ∼260 K (∼0.53 eV), ∼305 K (∼0.63 eV), and ∼360 K (0.91 eV), in the HPSI 4H-SiC will be discussed.
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identification of electron irradiation defects in semi insulating gaas by normalized Thermally Stimulated Current measurements
Physical Review B, 1997Co-Authors: David C Look, Z.-q. Fang, Joseph W Hemsky, P KengkanAbstract:Primary defects induced by 1 MeV electron irradiation have been quantitatively studied in semi-insulating (SI) GaAs by using normalized Thermally Stimulated Current spectroscopy, a new technique. Defects identical to (or similar to) those known in the Thermally Stimulated Current literature as T{sub 6}{sup {asterisk}}(0.13 eV), T{sub 5}(0.34 eV), and T{sub 4}(0.31 eV) are produced at rates 0.70, 0.08, and 0.23 cm{sup {minus}1}, respectively; T{sub 5} is also a strong trap in unirradiated SI GaAs. The defects T{sub 6}{sup {asterisk}} and T{sub 4} correspond closely to the irradiation-induced traps E2(0.14 eV) and E3(0.30 eV), studied extensively by deep-level transient spectroscopy and Hall-effect measurements and assigned to the As vacancy. We thus infer that traps T{sub 6}{sup {asterisk}} and T{sub 4} (and probably also T{sub 5}) in SI GaAs have As-vacancy character. {copyright} {ital 1997} {ital The American Physical Society}
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Thermally Stimulated Current trap in gan
Applied Physics Letters, 1996Co-Authors: David C Look, Z.-q. Fang, O Aktas, A Botchkarev, A Salvador, H MorkocAbstract:A Thermally Stimulated Current peak, occurring at 100 K for a heating rate of 0.4 K/s, has been found in semi‐insulating GaN grown by molecular beam epitaxy. This peak has contributions from two traps, with the main trap described by the following parameters: emission thermal activation energy E≂90±2 meV, effective capture cross‐section σ≂3±1×10−22 cm−2, and Nμτ≂3±1 × 1014 cm−1 V −1, where N is the trap concentration, μ the mobility, and τ the free‐carrier lifetime. This trap is much deeper than the typical shallow donors in conducting GaN, but shallower than any of the centers reported in recent deep level transient spectroscopy measurements.
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Point defects in undoped semi-insulating GaAs: correlation between Thermally Stimulated Current and positron annihilation spectroscopies
Proceedings of Semiconducting and Semi-Insulating Materials Conference, 1996Co-Authors: Z.-q. Fang, D.c. Look, S. Kuisma, K. Saarinen, P. HautojarviAbstract:Point defects and the main electron traps in undoped semi-insulating GaAs grown by vertical gradient freeze and high- and low-pressure liquid encapsulated Czochralski techniques have been studied by positron annihilation (PAS) and Thermally Stimulated Current (TSC) spectroscopies, respectively. We find good correlations between the concentrations of the TSC traps T/sub 2/ (0.63 eV) and T/sub 5/ (0.35 eV), and the PAS identified-defects As/sub Ga/ and V/sub As/, respectively. A good correlation between the concentration of intrinsic acceptors (V/sub Ga/ and Ga/sub As/) measured by PAS, and the total acceptor concentration measured by infrared absorption, is also found.
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traps in semi insulating inp studied by Thermally Stimulated Current spectroscopy
Applied Physics Letters, 1992Co-Authors: Z.-q. Fang, David C Look, J.h. ZhaoAbstract:Traps in Fe‐doped semi‐insulating InP samples have been studied by Thermally Stimulated Current spectroscopy with IR (hν≤1.12 eV) excitation at 81 K. The possible involvement of native defects in determining the compensation mechanisms is suggested based on the observation of other than the usual 0.64 eV Fe‐related activation energy for the dark Current in one of the four samples supplied from different sources. A metastable behavior of traps in another sample was found and explained by a charge‐controlled defect reaction model. Three out of the six traps observed are suggested to be electron traps and one among the other three traps is believed to be a hole trap.