Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:19955132
B. Tillack, J. Schlote, G. Ritter, D. Krüger, G. Morgenstern, P. Gaworzewski
Sharp profiles of boron were prepared by Low Pressure (Rapid Thermal) Chemical Vapor Deposition (LP(RT)CVD). Two different approaches for the delta doping were used. In the first case the dopants were incorporated into the growing film. The process was kinetically controlled. By this way B-delta-layers with a steepness of 1.7 nm/decade were measured by Secondary ion mass spectrometry (SIMS) for the profiles prepared. In the second case the doping was performed during an interruption of layer growth. The process was controlled by the surface adsorption equilibrium of dopants. Using this regime B-delta-layers of 1 monolayer and with a steepness of 1.4 nm/decade were obtained in SiGe. The values of the estimated steepness represent an extremely sharp profile for a CVD process. Structural properties of the delta-doped layers were investigated using cross sectional transmission electron microscopy (XTEM). The steepness estimated by SIMS was compared with high depth resolution spreading resistance (SR) measurements which detect the electrical active boron only.
{"title":"Delta Doping in Si and SiGe by LP(RT)CVD","authors":"B. Tillack, J. Schlote, G. Ritter, D. Krüger, G. Morgenstern, P. Gaworzewski","doi":"10.1051/JPHYSCOL:19955132","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:19955132","url":null,"abstract":"Sharp profiles of boron were prepared by Low Pressure (Rapid Thermal) Chemical Vapor Deposition (LP(RT)CVD). Two different approaches for the delta doping were used. In the first case the dopants were incorporated into the growing film. The process was kinetically controlled. By this way B-delta-layers with a steepness of 1.7 nm/decade were measured by Secondary ion mass spectrometry (SIMS) for the profiles prepared. In the second case the doping was performed during an interruption of layer growth. The process was controlled by the surface adsorption equilibrium of dopants. Using this regime B-delta-layers of 1 monolayer and with a steepness of 1.4 nm/decade were obtained in SiGe. The values of the estimated steepness represent an extremely sharp profile for a CVD process. Structural properties of the delta-doped layers were investigated using cross sectional transmission electron microscopy (XTEM). The steepness estimated by SIMS was compared with high depth resolution spreading resistance (SR) measurements which detect the electrical active boron only.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78902979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995535
C. Bisch, Y. Wang, F. Teyssandier
The formation of thin films in the conventional thermally activated chemical vapour deposition process is based on heterogeneous reactions involved in surface nucleation and growth. Nevertheless, the influence of homogeneous reactions has often been underestimated, and the intermediate species that are formed from homogeneous reactions may have a great influence on the deposition mechanism. In order to study the formation of these species, a specific reactor has been designed, in which the effects of gas-phase and surface reactions can be separated and so clearly identified. In order to limit the influence of surface phenomena, a so called wall-less reactor has been developed. In such a reactor, the reactive gas mixture is heated by mixing with a hot inert gas. Two basic configurations have preliminary been optimized by simulation modelling using the Si-H chemical system. A reactor has been designed according to these calculations. Comparison of the calculated flow pattern with that visualized by the laser sheet method shows an excellent agreement, that partially validates our model. The reactor is coupled with Raman spectroscopy, that allows both the determination of the local temperature of the gas phase and the detection of gaseous species.
{"title":"Wall-Less Like Reactor : Simulation and Experimental Results","authors":"C. Bisch, Y. Wang, F. Teyssandier","doi":"10.1051/JPHYSCOL:1995535","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995535","url":null,"abstract":"The formation of thin films in the conventional thermally activated chemical vapour deposition process is based on heterogeneous reactions involved in surface nucleation and growth. Nevertheless, the influence of homogeneous reactions has often been underestimated, and the intermediate species that are formed from homogeneous reactions may have a great influence on the deposition mechanism. In order to study the formation of these species, a specific reactor has been designed, in which the effects of gas-phase and surface reactions can be separated and so clearly identified. In order to limit the influence of surface phenomena, a so called wall-less reactor has been developed. In such a reactor, the reactive gas mixture is heated by mixing with a hot inert gas. Two basic configurations have preliminary been optimized by simulation modelling using the Si-H chemical system. A reactor has been designed according to these calculations. Comparison of the calculated flow pattern with that visualized by the laser sheet method shows an excellent agreement, that partially validates our model. The reactor is coupled with Raman spectroscopy, that allows both the determination of the local temperature of the gas phase and the detection of gaseous species.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90898548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995599
A. G. Dias, J. Breda, P. Moretto, J. Ordelman
The engineering of conventional TiN coatings to attain hardness of the order of ultrahard coatings (e.g. c-BN) by a controlled incorporation of silicon atoms in the titanium nitride lattice leading to the formation of a TiN-Si 3 N 4 composite material is discussed. An a-priori thermodynamic approach complemented by thermochemical equilibrium calculations was used to evaluate convenient precursors and processing parameters for the production of this novel coating material. The multiphase nature of preliminary test samples deposited by PACVD is confirmed by X-ray diffraction, IR spectroscopy and EPMA analysis. The films are made up of TiN nanocrystallites embedded in an amorphous Si 3 N 4 tissue with small amounts of free Si, as predicted by previous Ti-Si-N phase diagram calculations.
{"title":"Development of TiN-Si3N4 Nano Composite Coatings for Wear Resistance Applications","authors":"A. G. Dias, J. Breda, P. Moretto, J. Ordelman","doi":"10.1051/JPHYSCOL:1995599","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995599","url":null,"abstract":"The engineering of conventional TiN coatings to attain hardness of the order of ultrahard coatings (e.g. c-BN) by a controlled incorporation of silicon atoms in the titanium nitride lattice leading to the formation of a TiN-Si 3 N 4 composite material is discussed. An a-priori thermodynamic approach complemented by thermochemical equilibrium calculations was used to evaluate convenient precursors and processing parameters for the production of this novel coating material. The multiphase nature of preliminary test samples deposited by PACVD is confirmed by X-ray diffraction, IR spectroscopy and EPMA analysis. The films are made up of TiN nanocrystallites embedded in an amorphous Si 3 N 4 tissue with small amounts of free Si, as predicted by previous Ti-Si-N phase diagram calculations.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78848040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:19955125
S. Motojima, I. Hasegawa, H. Iwanaga
Micro-coiled fibers of carbon, SiC, Si 3 N 4 , TiC, ZrC and HfC were prepared by a metal-impurity activated chemical vapor deposition or vapour phase metallizing of the coiled carbon fibers. The growth conditions, morphology, growth mechanism and some properties were examined. The double-coiled carbon fibers were prepared using acetylene as a carbon source and various powders or plates of transition metals, metal carbides, MoS 2 , Ti 2 O 3 , and Ni single crystal plate as a catalyst at 650-850°C. The triple-coiled SiC fibers were prepared using coked rice husks and/or SiO as a Si-source and Ni, Cr or Fe as a catalyst at 1400-1500°C. The double-coiled TiC fibers were prepared by the PC1 3 activated CVD process on a graphite substrate using a Pt+Si or Pd+Si mixed catalyst at 1050-1250°C.
{"title":"Vapour Growth of Micro-Coiled Ceramic Fibers and their Properties","authors":"S. Motojima, I. Hasegawa, H. Iwanaga","doi":"10.1051/JPHYSCOL:19955125","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:19955125","url":null,"abstract":"Micro-coiled fibers of carbon, SiC, Si 3 N 4 , TiC, ZrC and HfC were prepared by a metal-impurity activated chemical vapor deposition or vapour phase metallizing of the coiled carbon fibers. The growth conditions, morphology, growth mechanism and some properties were examined. The double-coiled carbon fibers were prepared using acetylene as a carbon source and various powders or plates of transition metals, metal carbides, MoS 2 , Ti 2 O 3 , and Ni single crystal plate as a catalyst at 650-850°C. The triple-coiled SiC fibers were prepared using coked rice husks and/or SiO as a Si-source and Ni, Cr or Fe as a catalyst at 1400-1500°C. The double-coiled TiC fibers were prepared by the PC1 3 activated CVD process on a graphite substrate using a Pt+Si or Pd+Si mixed catalyst at 1050-1250°C.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78911439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995501
V. Hlavácek, J. Thiart, D. Orlicki
The paper reports on three major aspects of CVD reactor simulation: 1) Modeling of transport phenomena in conventional CVD and their effect on the film growth; 2) Modeling of plasma enhanced CVD and deposition of thin films; 3) Modeling of film growth and analysis of stability and morphology case studies. Case studies involve deposition of boron on W wire, deposition of Si-H and morphology development for a typical CVD reaction. Numerical methods of simulation are discussed in detail for each category mentioned above.
{"title":"Morphology and Film Growth in CVD Reactions","authors":"V. Hlavácek, J. Thiart, D. Orlicki","doi":"10.1051/JPHYSCOL:1995501","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995501","url":null,"abstract":"The paper reports on three major aspects of CVD reactor simulation: 1) Modeling of transport phenomena in conventional CVD and their effect on the film growth; 2) Modeling of plasma enhanced CVD and deposition of thin films; 3) Modeling of film growth and analysis of stability and morphology case studies. Case studies involve deposition of boron on W wire, deposition of Si-H and morphology development for a typical CVD reaction. Numerical methods of simulation are discussed in detail for each category mentioned above.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"195 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76862796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:19955100
A. Sassella, A. Borghesi, S. Rojas, L. Zanotti
Optical characterization of dielectric films used in integrated circuit device manufacturing can give information on their optical behavior as well as on their structural properties and composition. The results obtained on several undoped and doped silicon oxides, silicon oxynitrides, and silicon nitrides usually employed for microelectronic applications both in the ultraviolet-visible and infrared spectral ranges are illustrated.
{"title":"Optical Properties of CVD-Deposited Dielectric Films for Microelectronic Devices","authors":"A. Sassella, A. Borghesi, S. Rojas, L. Zanotti","doi":"10.1051/JPHYSCOL:19955100","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:19955100","url":null,"abstract":"Optical characterization of dielectric films used in integrated circuit device manufacturing can give information on their optical behavior as well as on their structural properties and composition. The results obtained on several undoped and doped silicon oxides, silicon oxynitrides, and silicon nitrides usually employed for microelectronic applications both in the ultraviolet-visible and infrared spectral ranges are illustrated.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90947621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995573
G. Beshkov, D. Dimitrov, S. Georgiev, T. Dimitrova
In this work the properties of PECVD-carbon films before and after Rapid Thermal Annealing (RTA) are presented. The thickness of the investigated films is in the range 50 - 6000A. The layers are annealed at 1400°C for different times of 1s to 3 min in vacuum 5 x 10 -5 Torr. Raman investigation has been performed before and after annealing.
{"title":"Deposition and Properties of Thin PECVD Carbon Films After Rapid Thermal Annealing","authors":"G. Beshkov, D. Dimitrov, S. Georgiev, T. Dimitrova","doi":"10.1051/JPHYSCOL:1995573","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995573","url":null,"abstract":"In this work the properties of PECVD-carbon films before and after Rapid Thermal Annealing (RTA) are presented. The thickness of the investigated films is in the range 50 - 6000A. The layers are annealed at 1400°C for different times of 1s to 3 min in vacuum 5 x 10 -5 Torr. Raman investigation has been performed before and after annealing.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84227051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995505
M. Hierlemann, H. Simka, K. Jensen, M. Utz
Very limited experimental data are available on thermal decomposition of germane in the gas phase. Recent developments in theoretical quantum chemistry techniques such as ab initio Hartree-Fock and density functional methods have made accurate determination of molecular properties possible. Systematic development of a detailed gas-phase decomposition mechanism for germane using ab initio molecular orbital calculations is described in this work. A decomposition pathway for germane and higher germanes is proposed and the relevant reaction rates are calculated using transition state theory combined with unimolecular and chemical activation treatments. The decomposition model is implemented into a realistic thermal-fluid simulation.
{"title":"Kinetic Modeling of the Gas Phase Decomposition of Germane by Computational Chemistry Techniques","authors":"M. Hierlemann, H. Simka, K. Jensen, M. Utz","doi":"10.1051/JPHYSCOL:1995505","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995505","url":null,"abstract":"Very limited experimental data are available on thermal decomposition of germane in the gas phase. Recent developments in theoretical quantum chemistry techniques such as ab initio Hartree-Fock and density functional methods have made accurate determination of molecular properties possible. Systematic development of a detailed gas-phase decomposition mechanism for germane using ab initio molecular orbital calculations is described in this work. A decomposition pathway for germane and higher germanes is proposed and the relevant reaction rates are calculated using transition state theory combined with unimolecular and chemical activation treatments. The decomposition model is implemented into a realistic thermal-fluid simulation.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"81 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82084574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995502
S. Berg, Claes Nender
Modeling of reactive sputter deposition processes is a very important tool for fast and inventive process development. A short review with some new results is given for a set of previously presented reactive sputtering models that has been successfull in describing and predicting the processes. Examples are given for each case of reactive sputtering with one target and one reactive gas, reactive compound- and co-sputtering as well as reactive sputtering using two reactive gases. The importance of process control in order to control the inherent instabilities and composition, is emphasized.
{"title":"Modeling of Mass Transport and Gas Kinetics of the Reactive Sputtering Process","authors":"S. Berg, Claes Nender","doi":"10.1051/JPHYSCOL:1995502","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995502","url":null,"abstract":"Modeling of reactive sputter deposition processes is a very important tool for fast and inventive process development. A short review with some new results is given for a set of previously presented reactive sputtering models that has been successfull in describing and predicting the processes. Examples are given for each case of reactive sputtering with one target and one reactive gas, reactive compound- and co-sputtering as well as reactive sputtering using two reactive gases. The importance of process control in order to control the inherent instabilities and composition, is emphasized.","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"177 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79865369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-06-01DOI: 10.1051/JPHYSCOL:1995562
K. Fröhlich, J. Šouc, D. Machajdík, A. Kobzev, F. Weiss, J. Sénateur, K. Dahmen
We have examined the properties of thin epitaxial CeO 2 films prepared by aerosol MOCVD. The films were deposited on (1102) sapphire at deposition temperatures between 500 °C and 900°C. The best properties were observed for the film grown at high deposition temperatures. The films have thickness ∼ 0.2 μm and the full width at half maximum of the rocking curve 0.3° - 0.4°. The minimal yield measured by backscattering spectrometry in the channeling mode was 5.5%, confirming high preferred orientation of the deposited films. The epitaxial character of the CeO 2 films was revealed by the measurement of the φ-scan. The aerosol MOCVD CeO 2 films were found to be suitable as a buffer layer for a preparation of superconducting high-T c films. YBa 2 Cu 3 O 1 superconducting films deposited on the CeO 2 /(1102) sapphire exhibit superconducting transition temperature T 0(R=0) = 86 K
研究了气溶胶MOCVD法制备的ceo2外延薄膜的性能。在500 ~ 900℃的沉积温度下，薄膜被沉积在(1102)蓝宝石上。在高沉积温度下生长的薄膜具有最佳的性能。膜的厚度为~ 0.2 μm，全宽为0.3°~ 0.4°。在通道模式下，后向散射光谱测量的最小产率为5.5%，证实了沉积膜的高择优取向。通过φ-扫描测量，揭示了ceo2薄膜的外延特性。发现气溶胶MOCVD ceo2薄膜适合作为制备超导高温度c薄膜的缓冲层。在ceo2 /(1102)蓝宝石上沉积的YBa 2 Cu 3 O 1超导薄膜表现出超导转变温度t0 (R=0) = 86 K
{"title":"Properties of Thin Epitaxial Aerosol MOCVD CeO2 Films Grown on (1102) Sapphire","authors":"K. Fröhlich, J. Šouc, D. Machajdík, A. Kobzev, F. Weiss, J. Sénateur, K. Dahmen","doi":"10.1051/JPHYSCOL:1995562","DOIUrl":"https://doi.org/10.1051/JPHYSCOL:1995562","url":null,"abstract":"We have examined the properties of thin epitaxial CeO 2 films prepared by aerosol MOCVD. The films were deposited on (1102) sapphire at deposition temperatures between 500 °C and 900°C. The best properties were observed for the film grown at high deposition temperatures. The films have thickness ∼ 0.2 μm and the full width at half maximum of the rocking curve 0.3° - 0.4°. The minimal yield measured by backscattering spectrometry in the channeling mode was 5.5%, confirming high preferred orientation of the deposited films. The epitaxial character of the CeO 2 films was revealed by the measurement of the φ-scan. The aerosol MOCVD CeO 2 films were found to be suitable as a buffer layer for a preparation of superconducting high-T c films. YBa 2 Cu 3 O 1 superconducting films deposited on the CeO 2 /(1102) sapphire exhibit superconducting transition temperature T 0(R=0) = 86 K","PeriodicalId":17944,"journal":{"name":"Le Journal De Physique Colloques","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"1995-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76584274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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