Pub Date : 1993-08-02DOI: 10.1109/CORNEL.1993.303114
T. Winslow, A. Morris, R. Trew
A gate breakdown model for MESFETs is presented. The model is based on quantum tunneling initiated avalanche ionization. The breakdown model is incorporated into a physics based MESFET model. Forward and reverse gate conduction an shown to be the main factors in determining the power and efficiency of MESFET amplifiers.<>
{"title":"An improved gate breakdown model for studying high efficiency MESFET operation","authors":"T. Winslow, A. Morris, R. Trew","doi":"10.1109/CORNEL.1993.303114","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303114","url":null,"abstract":"A gate breakdown model for MESFETs is presented. The model is based on quantum tunneling initiated avalanche ionization. The breakdown model is incorporated into a physics based MESFET model. Forward and reverse gate conduction an shown to be the main factors in determining the power and efficiency of MESFET amplifiers.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121189839","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303113
J. Sheridan, B. Nechay, D. Bloom, P. Solomon, Y. Pao
We report the fabrication of a 1 /spl mu/m photoconductive gap voltage step generator with constant output voltage of 0.10 V for 100 ps and a 2 ps rise time. The photoconductor is fabricated on GaAs/AlGaAs MODFET material and uses the two-dimensional electron gas in the FET channel as the conductive medium. It is fully process-compatible with MODFETs. In devices with standard ohmic contacts, the output current stayed constant for up to 50 ps, even though the electric field in the gap is expected to collapse in less than 1 ps. Two-dimensional device simulations show that, although the field in the gap does collapse on the expected time scale, the current is initially determined by the contacts. A new photoconductor design, in which the ohmic contacts are laterally recessed from the etched gap region, further delayed field collapse, extending constant voltage operation to 100 ps.<>
{"title":"Delay of field collapse in photoconductive gaps fabricated on GaAs/AlGaAs MODFET material","authors":"J. Sheridan, B. Nechay, D. Bloom, P. Solomon, Y. Pao","doi":"10.1109/CORNEL.1993.303113","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303113","url":null,"abstract":"We report the fabrication of a 1 /spl mu/m photoconductive gap voltage step generator with constant output voltage of 0.10 V for 100 ps and a 2 ps rise time. The photoconductor is fabricated on GaAs/AlGaAs MODFET material and uses the two-dimensional electron gas in the FET channel as the conductive medium. It is fully process-compatible with MODFETs. In devices with standard ohmic contacts, the output current stayed constant for up to 50 ps, even though the electric field in the gap is expected to collapse in less than 1 ps. Two-dimensional device simulations show that, although the field in the gap does collapse on the expected time scale, the current is initially determined by the contacts. A new photoconductor design, in which the ohmic contacts are laterally recessed from the etched gap region, further delayed field collapse, extending constant voltage operation to 100 ps.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130265102","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303099
J. L. Huber, M. Reed, G. Kramer, M. Adams, C. Fernando, W. Frensley
We have realized a series InAs/AlSb/GaSb tunneling structures in which both interband and intraband tunneling occur, dependent on injection energy. The baseline structure consists of a single InAs well with GaSb barriers which serve as quantum wells for interband tunneling and barriers for intraband tunneling. At low biases, interband tunneling occurs through a coupled double well structure in the GaSb valence bands. At higher biases, intraband tunneling occurs through the InAs quantum well. The addition of a thin AlSb barrier at different points in the structure changes both the strength and number of peaks in the I-V/G-V characteristics.<>
{"title":"Resonant interband and intraband tunneling in InAs/AlSb/GaSb double barrier diodes","authors":"J. L. Huber, M. Reed, G. Kramer, M. Adams, C. Fernando, W. Frensley","doi":"10.1109/CORNEL.1993.303099","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303099","url":null,"abstract":"We have realized a series InAs/AlSb/GaSb tunneling structures in which both interband and intraband tunneling occur, dependent on injection energy. The baseline structure consists of a single InAs well with GaSb barriers which serve as quantum wells for interband tunneling and barriers for intraband tunneling. At low biases, interband tunneling occurs through a coupled double well structure in the GaSb valence bands. At higher biases, intraband tunneling occurs through the InAs quantum well. The addition of a thin AlSb barrier at different points in the structure changes both the strength and number of peaks in the I-V/G-V characteristics.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132153024","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303070
Z. Abid, S. Mcalister, W. Mckinnon
GaInP/GaAs/GaInP double heterostructure bipolar transistors, emitter area of 50/spl times/50 (/spl mu/m)/sup 2/, with a DC gain of 445 and breakdown voltage (V/sub CBO/) of more than 17 V have been fabricated. The Gummel plots give an ideality factor of 1.01 for the collector current and 1.1 for the base current, and the devices show gain down to collector currents of 10/sup -9/A. A higher gain, more than 800, was recorded for a smaller device, 20/spl times/50 (/spl mu/m)/sup 2/ emitter, but the breakdown voltages were lower.<>
{"title":"GaInP/GaAs heterostructure bipolar transistors with high gain and high breakdown voltages","authors":"Z. Abid, S. Mcalister, W. Mckinnon","doi":"10.1109/CORNEL.1993.303070","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303070","url":null,"abstract":"GaInP/GaAs/GaInP double heterostructure bipolar transistors, emitter area of 50/spl times/50 (/spl mu/m)/sup 2/, with a DC gain of 445 and breakdown voltage (V/sub CBO/) of more than 17 V have been fabricated. The Gummel plots give an ideality factor of 1.01 for the collector current and 1.1 for the base current, and the devices show gain down to collector currents of 10/sup -9/A. A higher gain, more than 800, was recorded for a smaller device, 20/spl times/50 (/spl mu/m)/sup 2/ emitter, but the breakdown voltages were lower.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132222446","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303098
W. Chen, G. Munns, D. Knightly, J. East, G. Haddad
Resonant tunneling bipolar transistors (RTBT's) have been systematically studied using chemical beam epitaxy (CBE) for the first time. The RTBT structure studied is a InP-based transistor, consisting of single or multiple AlAs/In/sub 0.75/Ga/sub 0.25/As/AlAs RTD's in the emitter layer of a conventional heterojunction bipolar transistor (HBT) and an InGaAs or InGaAsP collector layer. Using the InGaAsP collector layer, the RTBT showed an improvement of breakdown voltage from 4 V to 10 V. The averaged DC /spl beta/'s are around 10 and 20 at 300 K and 77 K, respectively. In the transfer I-V characteristics, the RTBT showed 1 to 4 negative differential transconductance (NDT) peaks with peak-to-valley current ratios of 1.5 to 5.28 at 300 K. Using such NDT peaks, several RTBT digital functions were demonstrated at room temperature, including a frequency multiplier and exclusive NOR gate.<>
{"title":"InGaAs/AlAs/InGaAsP resonant tunneling bipolar transistors grown by chemical beam epitaxy","authors":"W. Chen, G. Munns, D. Knightly, J. East, G. Haddad","doi":"10.1109/CORNEL.1993.303098","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303098","url":null,"abstract":"Resonant tunneling bipolar transistors (RTBT's) have been systematically studied using chemical beam epitaxy (CBE) for the first time. The RTBT structure studied is a InP-based transistor, consisting of single or multiple AlAs/In/sub 0.75/Ga/sub 0.25/As/AlAs RTD's in the emitter layer of a conventional heterojunction bipolar transistor (HBT) and an InGaAs or InGaAsP collector layer. Using the InGaAsP collector layer, the RTBT showed an improvement of breakdown voltage from 4 V to 10 V. The averaged DC /spl beta/'s are around 10 and 20 at 300 K and 77 K, respectively. In the transfer I-V characteristics, the RTBT showed 1 to 4 negative differential transconductance (NDT) peaks with peak-to-valley current ratios of 1.5 to 5.28 at 300 K. Using such NDT peaks, several RTBT digital functions were demonstrated at room temperature, including a frequency multiplier and exclusive NOR gate.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133980561","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303084
Manisha Ramesh Deshpande, N.H. Dekker, J. Sleight, J. L. Huber, E.S. Hornbeck, M. Reed, R. Matyi, Y. Kao, C. Fernando, W. Frensley
A novel pre-resonant conductance structure is observed in single and double well GaAs/Ga/sub x/Al/sub 1-x/As resonant tunneling heterostructures. This structure is attributed to single electron tunneling through donor bound states in the quantum well as they cross the Fermi level. Peaks in conductance are observed in devices as large as (64/spl mu/)/sup 2/. We observe for the first time donor binding energies in quantum wells as large as 35 meV, which is probably due to the formation of a donor complex. An impressive impurity tunneling conductance structure is observed in double quantum well structures with conductance peak heights varying over 3 orders of magnitude. Conductance peaks are observed before and after the main resonant current peak which are attributed to tunneling of electrons through impurities in one quantum well and the quantum state in the other well.<>
{"title":"Observation of novel conductance structure in GaAs/Ga/sub x/Al/sub 1-x/As resonant tunneling heterostructures","authors":"Manisha Ramesh Deshpande, N.H. Dekker, J. Sleight, J. L. Huber, E.S. Hornbeck, M. Reed, R. Matyi, Y. Kao, C. Fernando, W. Frensley","doi":"10.1109/CORNEL.1993.303084","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303084","url":null,"abstract":"A novel pre-resonant conductance structure is observed in single and double well GaAs/Ga/sub x/Al/sub 1-x/As resonant tunneling heterostructures. This structure is attributed to single electron tunneling through donor bound states in the quantum well as they cross the Fermi level. Peaks in conductance are observed in devices as large as (64/spl mu/)/sup 2/. We observe for the first time donor binding energies in quantum wells as large as 35 meV, which is probably due to the formation of a donor complex. An impressive impurity tunneling conductance structure is observed in double quantum well structures with conductance peak heights varying over 3 orders of magnitude. Conductance peaks are observed before and after the main resonant current peak which are attributed to tunneling of electrons through impurities in one quantum well and the quantum state in the other well.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130958083","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303124
W. Schaff, K. Hur, L. Eastman, R. Compton, P. Mandeville
The growth of pseudomorphic MODFET structures on a patterned substrate was investigated as a means of increasing the critical layer thickness of strained layers. Prior to growth, semi-insulating GaAs substrates were patterned and etched using chemically assisted ion beam etching to define a series of mesas. Double-doped pseudomorphic MODFET layers were then grown on the substrates by molecular beam epitaxy. To fabricate MODFETs on the resulting non-planar wafer, a new fabrication technique has been developed.<>
{"title":"Strained layer device epitaxy on patterned substrates [MODFETs]","authors":"W. Schaff, K. Hur, L. Eastman, R. Compton, P. Mandeville","doi":"10.1109/CORNEL.1993.303124","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303124","url":null,"abstract":"The growth of pseudomorphic MODFET structures on a patterned substrate was investigated as a means of increasing the critical layer thickness of strained layers. Prior to growth, semi-insulating GaAs substrates were patterned and etched using chemically assisted ion beam etching to define a series of mesas. Double-doped pseudomorphic MODFET layers were then grown on the substrates by molecular beam epitaxy. To fabricate MODFETs on the resulting non-planar wafer, a new fabrication technique has been developed.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131010739","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303075
K. Lipka, B. Splingart, U. Erben, E. Kohn
LT-GaAs MISFETs had been realized indicating a record 2.7 W/mm RF power handling capability. To optimize such LT-GaAs power MISFET structures, the MIS system containing a LT-GaAs insulator and an AlAs interfacial diffusion barrier to the channel has been analyzed. A noticeable parallel conductance was found in the insulator which is thought to be one of the key parameters to realize high gate to drain breakdown voltages. This conductivity however leads also to a g/sub m/-dispersion in the MHz range. Locus-curves of this system demonstrate a higher resistivity in the AlAs layer than in the LT-GaAs layer, indicating that the simple model of a single lossy capacitance does not describe the MIS diode completely. An extended electronic equivalent circuit for use in the FET model has been established.<>
{"title":"LT-GaAs-MIS-diode characteristics and equivalent circuit model","authors":"K. Lipka, B. Splingart, U. Erben, E. Kohn","doi":"10.1109/CORNEL.1993.303075","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303075","url":null,"abstract":"LT-GaAs MISFETs had been realized indicating a record 2.7 W/mm RF power handling capability. To optimize such LT-GaAs power MISFET structures, the MIS system containing a LT-GaAs insulator and an AlAs interfacial diffusion barrier to the channel has been analyzed. A noticeable parallel conductance was found in the insulator which is thought to be one of the key parameters to realize high gate to drain breakdown voltages. This conductivity however leads also to a g/sub m/-dispersion in the MHz range. Locus-curves of this system demonstrate a higher resistivity in the AlAs layer than in the LT-GaAs layer, indicating that the simple model of a single lossy capacitance does not describe the MIS diode completely. An extended electronic equivalent circuit for use in the FET model has been established.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114492016","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303108
A. Morris, R. Trew, C. T. Kelley, G. J. Hayes
Heterojunction bipolar transistors (HBTs) show promise as a high speed and high power density device for many circuit applications. However the quasi-static models found in standard circuit simulation tools can not treat fast transients in HBTs properly. This leads to inaccurate simulations at high frequency and of strongly non-linear operation. To properly account for the charge in transit through the device, non-quasi-static (NQS) models must be used. This work presents a model for the bipolar transistor formed from regional modules. Each module is a NQS solution to a specific region of the transistor and uses material and geometry inputs. These modules are solved for physical consistency during non-linear circuit simulation. The modularization allows appropriate approximations for each region to yield analytic solutions. The input parameters for the model reflect the physical structure of the device as much as possible to provide intuitive results and verifiability. This allows direct device optimization since all parameters are either uncorrelated or their correlations can be derived from process parameters. Thus the device can be optimized in its circuit environment. The model provides for many effects which previously required numerical simulation for accurate results. These include forward and reverse Early, Webster/Rittner, and Kirk/quasisaturation effects. By following the modular modeling scheme, these effects are simply the result of varying boundary conditions on each of the regional solutions. The modular model provides much of the physical insight of numerical models but with computational requirements on the same order as conventional circuit models.<>
{"title":"A non-quasi-static modular model for HBTs","authors":"A. Morris, R. Trew, C. T. Kelley, G. J. Hayes","doi":"10.1109/CORNEL.1993.303108","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303108","url":null,"abstract":"Heterojunction bipolar transistors (HBTs) show promise as a high speed and high power density device for many circuit applications. However the quasi-static models found in standard circuit simulation tools can not treat fast transients in HBTs properly. This leads to inaccurate simulations at high frequency and of strongly non-linear operation. To properly account for the charge in transit through the device, non-quasi-static (NQS) models must be used. This work presents a model for the bipolar transistor formed from regional modules. Each module is a NQS solution to a specific region of the transistor and uses material and geometry inputs. These modules are solved for physical consistency during non-linear circuit simulation. The modularization allows appropriate approximations for each region to yield analytic solutions. The input parameters for the model reflect the physical structure of the device as much as possible to provide intuitive results and verifiability. This allows direct device optimization since all parameters are either uncorrelated or their correlations can be derived from process parameters. Thus the device can be optimized in its circuit environment. The model provides for many effects which previously required numerical simulation for accurate results. These include forward and reverse Early, Webster/Rittner, and Kirk/quasisaturation effects. By following the modular modeling scheme, these effects are simply the result of varying boundary conditions on each of the regional solutions. The modular model provides much of the physical insight of numerical models but with computational requirements on the same order as conventional circuit models.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124017267","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 : 1993-08-02DOI: 10.1109/CORNEL.1993.303085
A. Sarangan, Wei-Ping Huang
In this paper, a coupled mode theory for electron wave directional couplers is presented. The theory includes the dephasing effect on electrons due to temporally random phase destroying collisions. Using this scheme, the switching characteristics of the electron wave directional coupler is studied.<>
{"title":"A coupled mode theory for electron wave directional couplers","authors":"A. Sarangan, Wei-Ping Huang","doi":"10.1109/CORNEL.1993.303085","DOIUrl":"https://doi.org/10.1109/CORNEL.1993.303085","url":null,"abstract":"In this paper, a coupled mode theory for electron wave directional couplers is presented. The theory includes the dephasing effect on electrons due to temporally random phase destroying collisions. Using this scheme, the switching characteristics of the electron wave directional coupler is studied.<<ETX>>","PeriodicalId":129440,"journal":{"name":"Proceedings of IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132235681","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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