Pub Date : 2002-08-07DOI: 10.1109/MIEL.2002.1003175
R. Kakanakov, L. Kassamakova-Kolaklieva, N. Hristeva, G. Lepoeva, Konstantinos Zekentes
Ti/Al/p-SiC and Ni/n-SiC ohmic contacts with improved electrical and thermal properties in respect to their application in high power and high temperature SiC devices are reported in this work. Contact resistivity as a function of annealing was investigated over the temperature range of 700/spl deg/C -950/spl deg/C. The lowest resistivity of 1.42/spl times/10/sup -5/ /spl Omega/.cm/sup 2/ for the Ti/Al contact was obtained after annealing at 900/spl deg/C while for the Ni contact the lowest resistivity of 4.9/spl times/10/sup -6/ /spl Omega/ cm/sup 2/ was achieved at 950/spl deg/C. The contact stability during prolonged ageing and at high operating temperatures and current density was studied as a criterion for their reliability. It was found that both contacts were thermally stable during ageing in an inert ambient (N/sub 2/) at high temperature of 600/spl deg/C for 100 hours as well as at operating temperatures up to 450/spl deg/C in air and at current density of 10/sup 3/ A/cm/sup 2/ passed through the contacts during the heating. The improved electrical and thermal properties of the Ti/Al/p-SiC and Ni/n-SiC ohmic contacts were demonstrated in the power p-n SiC diode developed.
{"title":"Thermally stable low resistivity ohmic contacts for high power and high temperature SiC device applications","authors":"R. Kakanakov, L. Kassamakova-Kolaklieva, N. Hristeva, G. Lepoeva, Konstantinos Zekentes","doi":"10.1109/MIEL.2002.1003175","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003175","url":null,"abstract":"Ti/Al/p-SiC and Ni/n-SiC ohmic contacts with improved electrical and thermal properties in respect to their application in high power and high temperature SiC devices are reported in this work. Contact resistivity as a function of annealing was investigated over the temperature range of 700/spl deg/C -950/spl deg/C. The lowest resistivity of 1.42/spl times/10/sup -5/ /spl Omega/.cm/sup 2/ for the Ti/Al contact was obtained after annealing at 900/spl deg/C while for the Ni contact the lowest resistivity of 4.9/spl times/10/sup -6/ /spl Omega/ cm/sup 2/ was achieved at 950/spl deg/C. The contact stability during prolonged ageing and at high operating temperatures and current density was studied as a criterion for their reliability. It was found that both contacts were thermally stable during ageing in an inert ambient (N/sub 2/) at high temperature of 600/spl deg/C for 100 hours as well as at operating temperatures up to 450/spl deg/C in air and at current density of 10/sup 3/ A/cm/sup 2/ passed through the contacts during the heating. The improved electrical and thermal properties of the Ti/Al/p-SiC and Ni/n-SiC ohmic contacts were demonstrated in the power p-n SiC diode developed.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125164873","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003158
J. van der Spiegel, R. Etienne-Cummings, M. Nishimura
The paper starts with a brief discussion of the biological vision system that serves as a model for the three types of vision sensors described later on. A retina-like CCD sensor whose computational properties are embedded in its structure is described first, followed by a CMOS tracking sensor that consists of a fovea for smooth pursuit and a periphery for saccadic motion control. This sensor incorporates logarithmic compression, edge detection, direction-of-motion detection and centroid localization. Finally, a CMOS sensor for the detection of image features is discussed. The sensor extracts lower-level features, such as line orientation, line stops, and intersections, in a hierarchical fashion, similar to what the simple and complex cells do in the biological system.
{"title":"Biologically inspired vision sensors","authors":"J. van der Spiegel, R. Etienne-Cummings, M. Nishimura","doi":"10.1109/MIEL.2002.1003158","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003158","url":null,"abstract":"The paper starts with a brief discussion of the biological vision system that serves as a model for the three types of vision sensors described later on. A retina-like CCD sensor whose computational properties are embedded in its structure is described first, followed by a CMOS tracking sensor that consists of a fovea for smooth pursuit and a periphery for saccadic motion control. This sensor incorporates logarithmic compression, edge detection, direction-of-motion detection and centroid localization. Finally, a CMOS sensor for the detection of image features is discussed. The sensor extracts lower-level features, such as line orientation, line stops, and intersections, in a hierarchical fashion, similar to what the simple and complex cells do in the biological system.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129352910","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003220
Vitezslav Benda, Zdenek Novak
This paper investigates the problem of evaluating the lifetime of a carrier measured by the OCVD (open circuit voltage decay) method on structures with a non-uniform carrier lifetime distribution. A simple model of two diodes connected in parallel (lumped charge approximation) has been used for evaluating the measured carrier lifetime. The theoretical analysis was experimentally verified.
{"title":"OCVD carrier lifetime measurements on an inhomogeneous diode structure","authors":"Vitezslav Benda, Zdenek Novak","doi":"10.1109/MIEL.2002.1003220","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003220","url":null,"abstract":"This paper investigates the problem of evaluating the lifetime of a carrier measured by the OCVD (open circuit voltage decay) method on structures with a non-uniform carrier lifetime distribution. A simple model of two diodes connected in parallel (lumped charge approximation) has been used for evaluating the measured carrier lifetime. The theoretical analysis was experimentally verified.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128558642","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003323
H. Wong, Y. Chan, S.W. Ma
In this work, we propose an improved switching scheme (called chaotic frequency modulation (CFM)) for switched-mode power supplies to suppress the electromagnetic interference (EMI) noise source. The basic principle of CFM is to use a chaotic signal to modulate the switching signal such that the harmonics of noise power is distributed evenly over the whole spectrum instead of concentrated at the switching frequency. When compared with the conventional pulse width modulation (PWM) scheme, significant improvements in both conducted and radiated EMI noise levels were found with CFM method. For conducted EMI, the peak noise level was reduced by 25 dB. For radiated EMI, we found that the noise was found mainly in the frequency range of 30 MHz to 230 MHz and the CFM scheme would help to reduce the peak noise level in this frequency range by 22 dB.
{"title":"Electromagnetic interference of switching mode power regulator with chaotic frequency modulation","authors":"H. Wong, Y. Chan, S.W. Ma","doi":"10.1109/MIEL.2002.1003323","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003323","url":null,"abstract":"In this work, we propose an improved switching scheme (called chaotic frequency modulation (CFM)) for switched-mode power supplies to suppress the electromagnetic interference (EMI) noise source. The basic principle of CFM is to use a chaotic signal to modulate the switching signal such that the harmonics of noise power is distributed evenly over the whole spectrum instead of concentrated at the switching frequency. When compared with the conventional pulse width modulation (PWM) scheme, significant improvements in both conducted and radiated EMI noise levels were found with CFM method. For conducted EMI, the peak noise level was reduced by 25 dB. For radiated EMI, we found that the noise was found mainly in the frequency range of 30 MHz to 230 MHz and the CFM scheme would help to reduce the peak noise level in this frequency range by 22 dB.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130085899","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003187
G. Popovic, A. Almansa, E. Chatzitheodoridis, D. Petrović, O. Del Medico, W. Brenner, F. Sumecz, H. Detter
The efforts to bring micro system technology (MST) closer to industrial production have been supported by the European network "handling and assembly of functionally adapted microcomponents" (HAFAM) under the EC programme "training and mobility of researchers". This paper presents some of the final results of the HAFAM network. Topics addressed in the paper are: adaptation of high precision positioning stages to the needs of handling and assembly of microparts; development of tools for handling and assembly and methods for automation; combination of different technologies in one fabrication process for batch assembly purposes; joining techniques; methods and devices for quality control and characterization of various MST structures during and after the assembly process; and finally, norms and standardisation.
{"title":"Handling and assembly in MST - final results of a European network","authors":"G. Popovic, A. Almansa, E. Chatzitheodoridis, D. Petrović, O. Del Medico, W. Brenner, F. Sumecz, H. Detter","doi":"10.1109/MIEL.2002.1003187","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003187","url":null,"abstract":"The efforts to bring micro system technology (MST) closer to industrial production have been supported by the European network \"handling and assembly of functionally adapted microcomponents\" (HAFAM) under the EC programme \"training and mobility of researchers\". This paper presents some of the final results of the HAFAM network. Topics addressed in the paper are: adaptation of high precision positioning stages to the needs of handling and assembly of microparts; development of tools for handling and assembly and methods for automation; combination of different technologies in one fabrication process for batch assembly purposes; joining techniques; methods and devices for quality control and characterization of various MST structures during and after the assembly process; and finally, norms and standardisation.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128710776","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003222
V. F. Mitin, V. V. Kholevchuk, R. Konakova, E. Venger, V. A. Odarich, O. Rudenko, M. Semen'ko, M. V. Khimenko
Structural, electrical and optical properties of Ge films on semi-insulating GaAs substrates have been investigated. Ge films were obtained using thermal evaporation in a vacuum onto semi-insulated GaAs(100) substrates. During the Ge deposition process the substrate temperature was varied from 120 to 450 /spl deg/C. The film thicknesses were varied from 0.8 up to 1.5 /spl mu/m. X-ray and electron diffraction, atomic force microscopy (AFM), multiangle ellipsometric and galvanomagnetic (Hall effect, resistance and magneto-resistance) measurements have been used for these investigations.
{"title":"Surface structure and electrical properties of Ge films on semi-insulating GaAs substrates","authors":"V. F. Mitin, V. V. Kholevchuk, R. Konakova, E. Venger, V. A. Odarich, O. Rudenko, M. Semen'ko, M. V. Khimenko","doi":"10.1109/MIEL.2002.1003222","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003222","url":null,"abstract":"Structural, electrical and optical properties of Ge films on semi-insulating GaAs substrates have been investigated. Ge films were obtained using thermal evaporation in a vacuum onto semi-insulated GaAs(100) substrates. During the Ge deposition process the substrate temperature was varied from 120 to 450 /spl deg/C. The film thicknesses were varied from 0.8 up to 1.5 /spl mu/m. X-ray and electron diffraction, atomic force microscopy (AFM), multiangle ellipsometric and galvanomagnetic (Hall effect, resistance and magneto-resistance) measurements have been used for these investigations.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128733461","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003150
G. Meijer, Li Xiujun
The paper reviews the architecture and design of low-cost high-performance sensor systems. These systems consist of a number of multiplexed sensor elements, sensor-specific front ends, modifiers and microcontroller or digital signal processors (DSPs). The object-oriented design approach is introduced as an approach to design low-cost high-performance systems. Constraints for the excitation signals of sensing elements are discussed and it is shown how a selective detection of the measurand can be obtained, with a high immunity for parasitic components, interfering signals and parameter drift. A set-up is presented in which the analog sensor signals are converted to analog signals in the time domain, using period-modulated oscillators. The A/D conversion of the time-domain signal can be implemented in the microcontroller or DSP. It is shown that, also in this case, the principles of the sigma-delta converters can be applied. Two case studies for systems designs are discussed: a universal sensor interface and a dynamic voltage processor.
{"title":"Smart sensor interface electronics","authors":"G. Meijer, Li Xiujun","doi":"10.1109/MIEL.2002.1003150","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003150","url":null,"abstract":"The paper reviews the architecture and design of low-cost high-performance sensor systems. These systems consist of a number of multiplexed sensor elements, sensor-specific front ends, modifiers and microcontroller or digital signal processors (DSPs). The object-oriented design approach is introduced as an approach to design low-cost high-performance systems. Constraints for the excitation signals of sensing elements are discussed and it is shown how a selective detection of the measurand can be obtained, with a high immunity for parasitic components, interfering signals and parameter drift. A set-up is presented in which the analog sensor signals are converted to analog signals in the time domain, using period-modulated oscillators. The A/D conversion of the time-domain signal can be implemented in the microcontroller or DSP. It is shown that, also in this case, the principles of the sigma-delta converters can be applied. Two case studies for systems designs are discussed: a universal sensor interface and a dynamic voltage processor.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124092823","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003305
Ping He, Wensong Chen, L. Tian, Litian Liu, Zhijian Li
Using the variational method, the two dimensional Poisson Equation is solved in the MOSFET device region including the gate oxide region, depletion region and buried oxide region (for SOI device). An analytical expression for the potential distribution together with a new natural gate length scale for MOSFET is derived. The 2-D effects in front gate dielectric, back gate dielectric and silicon film can all be taken into account in this derivation. The validity of electrical equivalent oxide thickness approximation is also investigated using this model. Comparison of the short channel effect for uniform channel doping bulk MOSFET, intrinsic channel doping bulk MOSFET, SOI MOSFET and double gated MOSFET is conducted using our model. The results are verified by 2D numerical simulation using the 2D device simulator MEDICI.
{"title":"Unified MOSFET scaling theory using variational method","authors":"Ping He, Wensong Chen, L. Tian, Litian Liu, Zhijian Li","doi":"10.1109/MIEL.2002.1003305","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003305","url":null,"abstract":"Using the variational method, the two dimensional Poisson Equation is solved in the MOSFET device region including the gate oxide region, depletion region and buried oxide region (for SOI device). An analytical expression for the potential distribution together with a new natural gate length scale for MOSFET is derived. The 2-D effects in front gate dielectric, back gate dielectric and silicon film can all be taken into account in this derivation. The validity of electrical equivalent oxide thickness approximation is also investigated using this model. Comparison of the short channel effect for uniform channel doping bulk MOSFET, intrinsic channel doping bulk MOSFET, SOI MOSFET and double gated MOSFET is conducted using our model. The results are verified by 2D numerical simulation using the 2D device simulator MEDICI.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117043325","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003183
Aleksandar Vujani, Robert Pavelka, Nadja Adamovi, Christoph Kment, Sladjan Miti, Werner Brenner, Gordana Popovi
In this paper we described briefly the activities done in the frame of development of a system for contactless detection of the vibrations of the middle ear ossicle. The system has been constructed in the form of a fiber-optic vibrometer, which can be used as the microphone of a totally implantable hearing aid. The current state of the art is described and the initial measurements are presented and commented upon.
{"title":"Development of a totally implantable hearing aid","authors":"Aleksandar Vujani, Robert Pavelka, Nadja Adamovi, Christoph Kment, Sladjan Miti, Werner Brenner, Gordana Popovi","doi":"10.1109/MIEL.2002.1003183","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003183","url":null,"abstract":"In this paper we described briefly the activities done in the frame of development of a system for contactless detection of the vibrations of the middle ear ossicle. The system has been constructed in the form of a fiber-optic vibrometer, which can be used as the microphone of a totally implantable hearing aid. The current state of the art is described and the initial measurements are presented and commented upon.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128541032","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 : 2002-08-07DOI: 10.1109/MIEL.2002.1003356
E. Atanassova, D. Spassov
Tantalum pentoxide thin layers (10-100 nm) obtained by thermal oxidation of rf sputtered Ta films on Si have been investigated with respect to their dielectric, structural and electrical properties. It is established that stoichiometric Ta/sub 2/O/sub 5/ detected at the surface of the layers is reduced to tantalum suboxides in their depth. The oxide parameters are discussed in terms of a presence of an unavoidable ultrathin SiO/sub 2/ between Si and Ta/sub 2/O/sub 5/ and bond defects in both the oxide and the interface transition region. Conditions which guarantee obtaining high quality tantalum oxide with a dielectric constant of 32 - 35 and a leakage current less than 10/sup -7/ - 10/sup -8/ A/cm/sup 2/ at 1.5 V (SiO/sub 2/ equivalent thickness of 2.5 - 3 nm) are established. These specifications make the layers obtained suitable alternative to SiO/sub 2/ for high density DRAMs application.
{"title":"Thermal Ta/sub 2/O/sub 5/ - alternative to SiO/sub 2/ for high density dynamic memories","authors":"E. Atanassova, D. Spassov","doi":"10.1109/MIEL.2002.1003356","DOIUrl":"https://doi.org/10.1109/MIEL.2002.1003356","url":null,"abstract":"Tantalum pentoxide thin layers (10-100 nm) obtained by thermal oxidation of rf sputtered Ta films on Si have been investigated with respect to their dielectric, structural and electrical properties. It is established that stoichiometric Ta/sub 2/O/sub 5/ detected at the surface of the layers is reduced to tantalum suboxides in their depth. The oxide parameters are discussed in terms of a presence of an unavoidable ultrathin SiO/sub 2/ between Si and Ta/sub 2/O/sub 5/ and bond defects in both the oxide and the interface transition region. Conditions which guarantee obtaining high quality tantalum oxide with a dielectric constant of 32 - 35 and a leakage current less than 10/sup -7/ - 10/sup -8/ A/cm/sup 2/ at 1.5 V (SiO/sub 2/ equivalent thickness of 2.5 - 3 nm) are established. These specifications make the layers obtained suitable alternative to SiO/sub 2/ for high density DRAMs application.","PeriodicalId":221518,"journal":{"name":"2002 23rd International Conference on Microelectronics. Proceedings (Cat. No.02TH8595)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131998724","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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