Pub Date : 1900-01-01DOI: 10.1109/IEDM.1992.307406
A. Miura, T. Yakihara, S. Kobayashi, S. Oka, A. Nonoyama, T. Fujita
We carried out sample fabrication of hybrid resonant tunneling bipolar transistors (RBT) by successive epitaxial growth of resonant tunneling diode (RTD) structures directly on the emitter of hetero bipolar transistors (HBTs). Strained layer superlattice RTD structures of In/sub 0.53/Ga/sub 0.47/As-AlAs-In/sub 0.53/Ga/sub 0.47/As-AlAs-In/sub 0.53/Ga/sub 0.47/As were used for the RTD portions. The HBT portions consisted of (In/sub 0.52/Al/sub 0.48/As)/sub 0.5/(In/sub 0.53/Ga/sub 0.47/As)/sub 0.5/-In/sub 0.53/Ga/sub 0.47/As HBT structures and their breakdown characteristics were considered. This hybrid RBT has a high concentration layer of 1 10/sup 19/ cm/sup -3/ between the emitter and the RTD which serves for the RTD lower electrode layer and the HBT emitter electrode as well. This enables the device to operate as an independent RTD or as an independent HBT, in addition to the operation as an RBT. In addition, since each of these devices can freely be designed separately without affecting each other, the degree of freedom in circuit design increases greatly. The hybrid RBTs that were trial-produced had good collector current peak-to-valley ratios of 20 at room temperatures, peak current density of 3*10/sup 4/A/cm/sup 2/, and current gain of 20. These devices also had very good breakdown and saturation characteristics that permit their use in digital circuit applications which require stable operation, reflecting the characteristics of the (In/sub 0.52/Al/sub 0.48/As)/sub 0.5/(In/sub 0.53/Ga/sub 0.47/As)/sub 0.5/-In/sub 0.53/Ga/sub 0.47/As HBT structure. These hybrid RBTs are expected to have the same speed of operation as the conventional RBTs. In addition to the above, since the speed of operation becomes faster than the conventional RBT in the independent mode of operation, these devices are extremely useful for optimal circuit design in terms of both new functions and high operation speed.<>
{"title":"Hybrid RBT with resonant-tunneling-diode and hetero-bipolar-transistor on InP substrate","authors":"A. Miura, T. Yakihara, S. Kobayashi, S. Oka, A. Nonoyama, T. Fujita","doi":"10.1109/IEDM.1992.307406","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307406","url":null,"abstract":"We carried out sample fabrication of hybrid resonant tunneling bipolar transistors (RBT) by successive epitaxial growth of resonant tunneling diode (RTD) structures directly on the emitter of hetero bipolar transistors (HBTs). Strained layer superlattice RTD structures of In/sub 0.53/Ga/sub 0.47/As-AlAs-In/sub 0.53/Ga/sub 0.47/As-AlAs-In/sub 0.53/Ga/sub 0.47/As were used for the RTD portions. The HBT portions consisted of (In/sub 0.52/Al/sub 0.48/As)/sub 0.5/(In/sub 0.53/Ga/sub 0.47/As)/sub 0.5/-In/sub 0.53/Ga/sub 0.47/As HBT structures and their breakdown characteristics were considered. This hybrid RBT has a high concentration layer of 1 10/sup 19/ cm/sup -3/ between the emitter and the RTD which serves for the RTD lower electrode layer and the HBT emitter electrode as well. This enables the device to operate as an independent RTD or as an independent HBT, in addition to the operation as an RBT. In addition, since each of these devices can freely be designed separately without affecting each other, the degree of freedom in circuit design increases greatly. The hybrid RBTs that were trial-produced had good collector current peak-to-valley ratios of 20 at room temperatures, peak current density of 3*10/sup 4/A/cm/sup 2/, and current gain of 20. These devices also had very good breakdown and saturation characteristics that permit their use in digital circuit applications which require stable operation, reflecting the characteristics of the (In/sub 0.52/Al/sub 0.48/As)/sub 0.5/(In/sub 0.53/Ga/sub 0.47/As)/sub 0.5/-In/sub 0.53/Ga/sub 0.47/As HBT structure. These hybrid RBTs are expected to have the same speed of operation as the conventional RBTs. In addition to the above, since the speed of operation becomes faster than the conventional RBT in the independent mode of operation, these devices are extremely useful for optimal circuit design in terms of both new functions and high operation speed.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121136101","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307333
H. Kinoshita, D. Kwong
The diffusion during rapid thermal annealing (RTA) of ion implanted boron and BF/sub 2/ was modeled by considering the reaction kinetics between point defects and boron. The diffusion model utilizes Monte Carlo generated point defect profiles, an extended defect model and a surface amorphization model for high dose implantation. Excellent simulation results have been achieved by using a single set of diffusion and kinetic parameters to model the enhanced diffusion of boron during RTA for a wide range of B and BF/sub 2/ implant doses.<>
{"title":"Physical model for the diffusion of ion implanted boron and BF/sub 2/ during rapid thermal annealing","authors":"H. Kinoshita, D. Kwong","doi":"10.1109/IEDM.1992.307333","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307333","url":null,"abstract":"The diffusion during rapid thermal annealing (RTA) of ion implanted boron and BF/sub 2/ was modeled by considering the reaction kinetics between point defects and boron. The diffusion model utilizes Monte Carlo generated point defect profiles, an extended defect model and a surface amorphization model for high dose implantation. Excellent simulation results have been achieved by using a single set of diffusion and kinetic parameters to model the enhanced diffusion of boron during RTA for a wide range of B and BF/sub 2/ implant doses.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125421905","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307337
A. Kersch, W. Morokoff, C. Werner, D. Restaino, B. Vollmer
The direct simulation Monte Carlo method is utilized to simulate the particle and energy distributions in a state of the art sputtering reactor used to deposit titanium films in small contact holes. The calculations provide information about particle and temperature distributions within the reactor, deposition rate profiles, and angular distributions of the atoms arriving at the substrate. The results agree quite well with experimental data.<>
{"title":"Modeling of a sputter reactor using the direct simulation Monte Carlo method","authors":"A. Kersch, W. Morokoff, C. Werner, D. Restaino, B. Vollmer","doi":"10.1109/IEDM.1992.307337","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307337","url":null,"abstract":"The direct simulation Monte Carlo method is utilized to simulate the particle and energy distributions in a state of the art sputtering reactor used to deposit titanium films in small contact holes. The calculations provide information about particle and temperature distributions within the reactor, deposition rate profiles, and angular distributions of the atoms arriving at the substrate. The results agree quite well with experimental data.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126749463","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307360
N. Shimizu, Y. Naito, Y. Itoh, Y. Shibata, K. Hashimoto, M. Nishio, A. Asai, K. Ohe, H. Umimoto, Y. Hirofuji
A new isolation technology, called PBR LOCOS (Poly Buffer Recessed LOCOS) process, has been developed for a 256Mbit DRAM with 0.72 mu m/sup 2/ cell. The features of the PBR LOCOS process are low bird's beak encroachment and defects free isolation, which are achieved by using shallow recess etching, buffer polysilicon, and silicon nitride sidewall. It is formed that the shallow recess etching provides high punch-through voltage of parasitic field transistors. The PBR LOCOS process allows the fabrication of 256Mbit DRAM cells.<>
{"title":"A poly-buffer recessed LOCOS process for 256 Mbit DRAM cells","authors":"N. Shimizu, Y. Naito, Y. Itoh, Y. Shibata, K. Hashimoto, M. Nishio, A. Asai, K. Ohe, H. Umimoto, Y. Hirofuji","doi":"10.1109/IEDM.1992.307360","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307360","url":null,"abstract":"A new isolation technology, called PBR LOCOS (Poly Buffer Recessed LOCOS) process, has been developed for a 256Mbit DRAM with 0.72 mu m/sup 2/ cell. The features of the PBR LOCOS process are low bird's beak encroachment and defects free isolation, which are achieved by using shallow recess etching, buffer polysilicon, and silicon nitride sidewall. It is formed that the shallow recess etching provides high punch-through voltage of parasitic field transistors. The PBR LOCOS process allows the fabrication of 256Mbit DRAM cells.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115985524","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307442
J. Campbell, K.-H. Li, C. Tsai
While numerous luminescence effects have been reported for Si-based materials, with few exceptions the efficiencies have been extremely low. Recent breakthroughs in this area such as the observation of strong, room temperature visible emission from porous Si have stimulated research on light emission from column IV materials. This paper reviews some of the accomplishments that may presage the development of Si-based light emitters.<>
{"title":"Luminescence from Si-based structures","authors":"J. Campbell, K.-H. Li, C. Tsai","doi":"10.1109/IEDM.1992.307442","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307442","url":null,"abstract":"While numerous luminescence effects have been reported for Si-based materials, with few exceptions the efficiencies have been extremely low. Recent breakthroughs in this area such as the observation of strong, room temperature visible emission from porous Si have stimulated research on light emission from column IV materials. This paper reviews some of the accomplishments that may presage the development of Si-based light emitters.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"226 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123001165","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307444
N. Hunt, E. Schubert, R. Logan, G. Zydzik
Resonant cavity light emitting diodes (RCLEDs) operating at 1.3 mu m and 1.5 mu m have been fabricated. The InGaAsP quantum well active region is positioned in the antinode of the optical resonance which is set up between an InP-InGaAsP distributed Bragg reflector (DBR) and a silver mirror. The resulting spontaneous emission through the substrate exhibits an enhancement of spectral power density and a reduction in linewidth by more than an order of magnitude compared to conventional devices. Such devices would be suitable for use in wavelength division multiplexing applications.<>
{"title":"Extremely narrow spectral widths from resonant cavity light-emitting diodes (RCLEDs) suitable for wavelength-division multiplexing at 1.3 mu m and 1.55 mu m","authors":"N. Hunt, E. Schubert, R. Logan, G. Zydzik","doi":"10.1109/IEDM.1992.307444","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307444","url":null,"abstract":"Resonant cavity light emitting diodes (RCLEDs) operating at 1.3 mu m and 1.5 mu m have been fabricated. The InGaAsP quantum well active region is positioned in the antinode of the optical resonance which is set up between an InP-InGaAsP distributed Bragg reflector (DBR) and a silver mirror. The resulting spontaneous emission through the substrate exhibits an enhancement of spectral power density and a reduction in linewidth by more than an order of magnitude compared to conventional devices. Such devices would be suitable for use in wavelength division multiplexing applications.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114608306","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307341
S. Begum, G. Scheitrum, B. Arfin
A three-dimensional nonlinear theory is being used to design and optimize the performance of a four cavity, 95 GHz harmonic gyroklystron amplifier. An efficiency of 19% with a gain of 37 dB was achieved for interaction between the pi mode of the vaned magnetron cavities and the fourth cyclotron harmonic of a 25 kV, 5 A axis encircling electron beam. The space charge forces in the beam and the losses in the cavity were neglected. A uniform magnetic field was assumed along the length of the device. It is expected that the magnetic field profiling will improve the efficiency to 21 to 24%.<>
{"title":"Large signal simulation and design of a 95 GHz harmonic gyroklystron amplifier","authors":"S. Begum, G. Scheitrum, B. Arfin","doi":"10.1109/IEDM.1992.307341","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307341","url":null,"abstract":"A three-dimensional nonlinear theory is being used to design and optimize the performance of a four cavity, 95 GHz harmonic gyroklystron amplifier. An efficiency of 19% with a gain of 37 dB was achieved for interaction between the pi mode of the vaned magnetron cavities and the fourth cyclotron harmonic of a 25 kV, 5 A axis encircling electron beam. The space charge forces in the beam and the losses in the cavity were neglected. A uniform magnetic field was assumed along the length of the device. It is expected that the magnetic field profiling will improve the efficiency to 21 to 24%.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117100541","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307445
F. Libsch
The threshold voltage instabilities in nitride/oxide dual gate dielectric hydrogenated amorphous silicon (a-Si:H) thin-film transistors are investigated as a function of stress time, stress temperature and stress bias. The obtained results are explained with a multiple trapping model, rather than weak bond breaking model. In our model, the injected carriers from the a-Si:H channel first thermalize in a broad distribution of localized band-tail states located at the a-Si:H/a-SiN/sub x/:H interface and in the a-SiN/sub x/:H transitional layer close to the interface, then move to deeper energies in amorphous silicon nitride at longer stress times, larger stress electric fields, or higher stress temperatures. The results of the model are consistent with the bias-stress-temperature data. Steady state (DC) as well as pulsed bias stress measurements have been employed to electrically characterize the instabilities in a-Si:H TFTs.<>
研究了氮/氧化物双栅介质氢化非晶硅(a- si:H)薄膜晶体管的阈值电压不稳定性与应力时间、应力温度和应力偏置的关系。所得结果用多重俘获模型而不是弱键断裂模型来解释。在我们的模型中，从a- si:H通道注入的载流子首先在a- si:H/a- sin /sub x/:H界面和靠近界面的a- sin /sub x/:H过渡层以广泛分布的局域带尾态热化，然后在更长的应力时间、更大的应力场或更高的应力温度下向非晶氮化硅中更深的能量移动。模型结果与偏应力-温度数据吻合较好。稳态(DC)和脉冲偏置应力测量已被用于表征a-Si:H tft的不稳定性。
{"title":"Steady state and pulsed bias stress induced degradation in amorphous silicon thin film transistors for active-matrix liquid crystal displays","authors":"F. Libsch","doi":"10.1109/IEDM.1992.307445","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307445","url":null,"abstract":"The threshold voltage instabilities in nitride/oxide dual gate dielectric hydrogenated amorphous silicon (a-Si:H) thin-film transistors are investigated as a function of stress time, stress temperature and stress bias. The obtained results are explained with a multiple trapping model, rather than weak bond breaking model. In our model, the injected carriers from the a-Si:H channel first thermalize in a broad distribution of localized band-tail states located at the a-Si:H/a-SiN/sub x/:H interface and in the a-SiN/sub x/:H transitional layer close to the interface, then move to deeper energies in amorphous silicon nitride at longer stress times, larger stress electric fields, or higher stress temperatures. The results of the model are consistent with the bias-stress-temperature data. Steady state (DC) as well as pulsed bias stress measurements have been employed to electrically characterize the instabilities in a-Si:H TFTs.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129086833","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307479
H. Sayama, S. Hara, H. Kimura, Y. Ohno, S. Satoh, M. Takai
A system for evaluation of soft-errors in Mbit DRAM was developed using 400 keV proton microprobes to reveal the correlation between an incident position of protons and susceptibility against soft-errors in a memory chip. A cell mode and a bit-line mode could be specified by incident positions of protons. Soft-errors were induced by the proton incidence within about 6 mu m around the memory cell, in particular easily induced within 4 mu m. Such regions in which soft-errors is induced by the proton incidence were found not to depend on the spot size of proton microprobes.<>
{"title":"Soft-error evaluation using proton microprobe for DRAMs","authors":"H. Sayama, S. Hara, H. Kimura, Y. Ohno, S. Satoh, M. Takai","doi":"10.1109/IEDM.1992.307479","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307479","url":null,"abstract":"A system for evaluation of soft-errors in Mbit DRAM was developed using 400 keV proton microprobes to reveal the correlation between an incident position of protons and susceptibility against soft-errors in a memory chip. A cell mode and a bit-line mode could be specified by incident positions of protons. Soft-errors were induced by the proton incidence within about 6 mu m around the memory cell, in particular easily induced within 4 mu m. Such regions in which soft-errors is induced by the proton incidence were found not to depend on the spot size of proton microprobes.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126913077","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 : 1900-01-01DOI: 10.1109/IEDM.1992.307336
K. Lucas, A. Strojwas
A new vector optical lithography simulator, METROPOLE, is presented. Rigorous simulations run quickly on a workstation for complex 2D regular and phase shifting masks, substrate bleaching, optical metrology and alignment problems. An analysis of a novel phase shifting techniques is undertaken to highlight the usefulness of the program.<>
{"title":"A new vector 2D photolithography simulation tool","authors":"K. Lucas, A. Strojwas","doi":"10.1109/IEDM.1992.307336","DOIUrl":"https://doi.org/10.1109/IEDM.1992.307336","url":null,"abstract":"A new vector optical lithography simulator, METROPOLE, is presented. Rigorous simulations run quickly on a workstation for complex 2D regular and phase shifting masks, substrate bleaching, optical metrology and alignment problems. An analysis of a novel phase shifting techniques is undertaken to highlight the usefulness of the program.<<ETX>>","PeriodicalId":287098,"journal":{"name":"1992 International Technical Digest on Electron Devices Meeting","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116191760","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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