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Endoscopic trans-esophageal submucosal tunneling surgery:A new therapeutic approach for diseases located around the aorta ventralis 预览
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作者 Ying Xiong Qian-Qian Chen +3 位作者 Ning-Li Chai Shun-Chang Jiao En-Qiang Ling Hu 《世界胃肠病学杂志:英文版》 SCIE CAS 2019年第1期85-94,共10页
AIM To assess the efficiency of endoscopic trans-esophageal submucosal tunneling surgery(EESTS)technique for diseases located around the aorta ventralis.METHODS Nine pigs were assigned to EESTs.The procedures were as ... AIM To assess the efficiency of endoscopic trans-esophageal submucosal tunneling surgery(EESTS)technique for diseases located around the aorta ventralis.METHODS Nine pigs were assigned to EESTs.The procedures were as follows:First,a long esophageal submucosal tunnel was established.Second,full-thickness myotomy was created.Third,an endoscope was entered into the abdominal cavity through a muscle incision and the endoscope was around the aorta ventralis.Eventually,celiac trunk ganglion neurolysis,partial hepatectomy and splenectomy,partial tissue resection in the area of the posterior peritoneum,and endoscopic submucosal dissection(ESD)combined with lymph node dissection were performed.The animals were given antibiotics for 5 d and necropsied 7 d after surgery.RESULTS In all surgeries,one pig died from intraperitoneal hemorrhage after doing partial splenectomy,while the other pigs were alive after successfully operating other surgeries.For surgery of celiac trunk ganglion damage,at necropsy,there was no exudation in the abdominal cavity.Regarding surgery of partial hepatectomy,the wound with part healing was observed in the left hepatic lobe,and no bleeding or obvious exudation was seen.In surgery of partial splenectomy,massive hemorrhage was observed on the splenic wound surface,and the metal clips could not stop bleeding.After surgery of retroperitoneal tissue resection,mild tissue adhesion was observed in the abdominal cavity of one animal,and another one suffered from severe infection.For surgery of ESD and lymph node dissection,a moderate tissue adhesion was observed.CONCLUSION EESTS is a feasible and safe technique for diseases located around the aorta ventralis. 展开更多
关键词 ENDOSCOPIC trans-esophageal SUBMUCOSAL TUNNELING SURGERY Diseases around the AORTA ventralis ENDOSCOPIC SUBMUCOSAL TUNNELING technique Abdominal SURGERY Animal model
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煤矿斜井施工技术分析 预览
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作者 张志龙 《建筑技术开发》 2019年第12期39-40,共2页
在矿山的建设过程中,斜井是其非常重要的组成部分,由于地址情况、施工工艺以及施工条件的影响,导致其施工难度较大,存在较多的不安全因素。为了保障煤矿斜井施工的顺利进行,就需要对整个施工过程进行系统全面的分析研究,并釆取有针对性... 在矿山的建设过程中,斜井是其非常重要的组成部分,由于地址情况、施工工艺以及施工条件的影响,导致其施工难度较大,存在较多的不安全因素。为了保障煤矿斜井施工的顺利进行,就需要对整个施工过程进行系统全面的分析研究,并釆取有针对性的斜井施工技术,确保各项施工措施的顺利实施以及确保斜井的施工质量符合要求。 展开更多
关键词 煤矿 斜井 掘进
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煤矿掘进巷道锚杆支护技术研究 预览
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作者 路瑞龙 《当代化工研究》 2019年第7期164-165,共2页
本文阐述了煤矿矿井的掘进巷道支护发展现状以及在矿井掘进工作中进行巷道锚杆支护的作用,并在巷道锚杆孔位和支护设计等角度分析了锚杆支护进行设计及施工方面的要求,某种程度上提高了煤矿矿井作业的安全性。
关键词 矿井 锚杆支护 掘进
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Advances in the study of the host-guest interaction by using coronene as the guest molecule
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作者 Jianqiao Li Yuxin Qian +1 位作者 Wubiao Duan Qingdao Zeng 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第2期292-298,共7页
Host-guest chemistry in two-dimensional (2D) networks has gained much interest for the new functionalities and potential applications, such as separation technology, photogenic crystals and biomimetic surfaces. Nanopo... Host-guest chemistry in two-dimensional (2D) networks has gained much interest for the new functionalities and potential applications, such as separation technology, photogenic crystals and biomimetic surfaces. Nanoporous supramolecular networks are assembled by a range of non-covalent forces like hydrogen bonds, van der Waals interactions and coordinate bonds, to immobilize guest molecules of different sizes and shapes. In this review, we mainly presented the effect of coronene on the host-guest architecture. Coronene (COR) is chosen to be the promising guest molecule and it can embed, cover, or change the host networks in different host-guest systems. All of the research in the review was finished with assistance of scanning tunneling microscope (STM). These studies were called upon impose controlling on host-guest systems and revealed the behaviors of COR clusters as guest molecules. 展开更多
关键词 HOST-GUEST chemistry CORONENE Molecular TEMPLATE 2D SELF-ASSEMBLY Scanning TUNNELING microscopy(STM)
大跨度框架下穿多股道顶进施工时铁路线路加固技术研究 预览
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作者 魏亚茹 《价值工程》 2019年第19期162-165,共4页
龙象公路在象山煤矿东侧下穿侯西铁路、运煤专线及编组站专用线等5条铁轨,公路设置2-14m框架下穿铁路。针对本项目为大跨度框架下穿铁路5股道顶进施工,施工难度高,安全压力大。通过采取纵横抬梁法+吊轨梁对既有铁路5股道进行线路加固,... 龙象公路在象山煤矿东侧下穿侯西铁路、运煤专线及编组站专用线等5条铁轨,公路设置2-14m框架下穿铁路。针对本项目为大跨度框架下穿铁路5股道顶进施工,施工难度高,安全压力大。通过采取纵横抬梁法+吊轨梁对既有铁路5股道进行线路加固,并顶进中运用了石蜡、黄油及塑料薄膜组成复合滑动层,滚杠、定向滑轮等措施,减小了框构桥顶进施工时的摩阻力,加快了施工进度,提高了顶进过程的安全性。 展开更多
关键词 大跨度框架 顶进施工 线路加固技术 减摩措施
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煤矿软岩巷道掘进支护技术探讨 预览
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作者 荆彦军 《当代化工研究》 2019年第7期17-18,共2页
掘进支护技术在软岩巷道施工建设中的应用效果,对整个巷道的稳固性和作业人员的人身安全起着重要作用,对保证煤矿企业的安全生产也具有重要意义。在对软岩巷道进行掘进支护过程中,出现了很多问题,比如软岩强度不高导致围岩应力水平较高... 掘进支护技术在软岩巷道施工建设中的应用效果,对整个巷道的稳固性和作业人员的人身安全起着重要作用,对保证煤矿企业的安全生产也具有重要意义。在对软岩巷道进行掘进支护过程中,出现了很多问题,比如软岩强度不高导致围岩应力水平较高,岩层中存在吸水膨胀特性的黏土矿物质会对软岩巷道的支护结构产生影响。所以为了降低围岩变形对巷道掘进支护工作带来的不利影响,需要采用一些方法措施来提高围岩强度和支护表力。目前在软岩巷道掘进作业中最常用的支护技术就是锚杆联合支护与锚网喷支护,合理掘进支护方式的选择要根据当地矿井的地质特点来决定。 展开更多
关键词 软岩巷道 掘进 支护技术
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Modified criterion for prediction of tunnel deformation in non-squeezing ground conditions 预览
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作者 Ako Daraei Shokrollah Zare 《现代交通学报:英文版》 2019年第1期11-24,共14页
The strength factor-based criterion for tunnel deformation prediction proposed by Hoek in 2000 is reckoned to be the most practical criterion among the tunnel deformation criteria since 1980s.In view of the fact that ... The strength factor-based criterion for tunnel deformation prediction proposed by Hoek in 2000 is reckoned to be the most practical criterion among the tunnel deformation criteria since 1980s.In view of the fact that Hoek’s criterion was obtained based on case studies under squeezing ground conditions,it has a limited range of applications,applicable mainly in squeezing tunnels.In this work,this criterion was modified by taking into consideration the conditions of eight unstable stations in three non-squeezing tunnels in Iran to amplify its application range.Relative displacements and strength factor(defined as a strength-to-stress ratio)were obtained in unstable stations first.Then,the parametric values were plotted on a Cartesian coordinate’s plane.By using the optimal regression line passing through all points,a criterion for prediction of tunnel deformation was proposed finally.A comparison made between the measured values and the ones predicted by the new criterion shows that the variance accounted for was 77%and the root mean square error was 2%,an acceptable accuracy and a small error implying the effectiveness of the new criterion in tunnel deformation prediction.In addition,the results show that the strength factor of 0.38 can be used to determine the boundary between squeezing and non-squeezing conditions;the behavior and type of failure of the tunnel would be predictable by use of the strength factor. 展开更多
关键词 Strength factor TUNNEL DEFORMATION Monitoring Failure type TUNNELING
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基于GNS3的IPSec-VPN仿真设计与实现 预览
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作者 吴志森 《九江职业技术学院学报》 2019年第1期21-23,17共4页
利用GNS3网络模拟器构建IPSec-VPN网络,实现密钥管理和交换、认证和数据篡改的安全机制。通过Ping工具和Wireshark对数据包进行测试和验证分析,保证了同一网络不同站点之间进行数据交换时对数据包是加密的。
关键词 GNS3 VPN IPSEC 隧道
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Method of Hill Tunneling via Weighted Simplex Centroid for Continuous Piecewise Linear Programming
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作者 Zhiming Xu Yu Bai +1 位作者 Kuangyu Liu Shuning Wang 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第3期301-316,共16页
This paper works on a heuristic algorithm with determinacy for the global optimization of Continuous PieceWise Linear(CPWL) programming. The widely applied CPWL programming can be equivalently transformed into D.C. pr... This paper works on a heuristic algorithm with determinacy for the global optimization of Continuous PieceWise Linear(CPWL) programming. The widely applied CPWL programming can be equivalently transformed into D.C. programming and concave optimization over a polyhedron. Considering that the super-level sets of concave piecewise linear functions are polyhedra, we propose the Hill Tunneling via Weighted Simplex Centroid(HTWSC) algorithm, which can escape a local optimum to reach the other side of its contour surface by cutting across the super-level set. The searching path for hill tunneling is established via the weighted centroid of a constructed simplex. In the numerical experiments, different weighting methods are studied first, and the best is chosen for the proposed HTWSC algorithm. Then, the HTWSC algorithm is compared with the hill detouring method and the software CPLEX for the equivalent mixed integer programming, with results indicating its superior performance in terms of numerical efficiency and the global search capability. 展开更多
关键词 global optimization PIECEWISE linear CONCAVE minimization cutting plane METHOD HILL TUNNELING
EJM340/4-2掘锚一体机在凉水井矿的应用
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作者 王佃武 《煤矿机械》 北大核心 2019年第3期118-120,共3页
针对采掘衔接紧张、掘进技术落后的现状,凉水井矿采用掘支运平行作业理念,结合4-2煤的地质条件和巷道规格,引入国产掘锚一体机,优化掘、支、运工艺,提高掘进自动化和智能化水平,实现了掘进效率的大幅提升。
关键词 掘锚一体机 掘进 平行作业
快速通过陷落柱大断面全锚喷浆支护的应用 预览
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作者 刘孟凯 《江西煤炭科技》 2019年第2期7-8,13共3页
山西霍宝干河煤矿2-106掘进工作面副巷掘进过程中遇2个陷落柱,经过对地质条件的分析,采用大断面全锚喷浆支护,支护强度达到了设计要求,有效降低了巷道维修工作量,节约业大量的人力、物力,取得了良好经济、社会效益。
关键词 煤巷掘进 大断面 过陷落柱 锚喷支护
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掘进巷道破碎带顶板支护的实践 预览
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作者 王金强 《山东煤炭科技》 2019年第3期3-5,共3页
巷道在掘进期间经常遇断层构造,受到构造应力的影响,前后顶板会出现破碎、局部冒顶现象,降低了巷道掘进效率,加大了顶板支护难度。对此,在承揽施工5402巷过断层带期间,根据矿方初步设计及主要存在的问题及实际生产需要提出了有效的顶板... 巷道在掘进期间经常遇断层构造,受到构造应力的影响,前后顶板会出现破碎、局部冒顶现象,降低了巷道掘进效率,加大了顶板支护难度。对此,在承揽施工5402巷过断层带期间,根据矿方初步设计及主要存在的问题及实际生产需要提出了有效的顶板控制措施,保证安全高效掘进施工。 展开更多
关键词 掘进 破碎带 支护
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General way to define tunneling time
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作者 舒正 郝小雷 +1 位作者 李卫东 陈京 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期27-31,共5页
With the development of attosecond science, tunneling time can now be measured experimentally with the attoclock technique. However, there are many different theoretical definitions of tunneling time and no consensus ... With the development of attosecond science, tunneling time can now be measured experimentally with the attoclock technique. However, there are many different theoretical definitions of tunneling time and no consensus has been achieved.Here, we bridge the relationship between different definitions of tunneling time based on a quantum travel time in onedimensional rectangular barrier tunneling problem. We find that the real quantum travel time tRe is equal to the Bohmian time tBohmian, which is related to the resonance lifetime of a bound state. The total quantum travel time τt can perfectly retrieve the transversal time tx and the Büttiker–Landauer time τBL in two opposite limits, regardless of the particle energy. 展开更多
关键词 TUNNELING TIME Buttiker–Landauer TIME Bohmian TIME
Comparison of tunneling currents in graphene nanoribbon tunnel field effect transistors calculated using Dirac-like equation and Schrodinger’s equation 预览
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作者 Endi Suhendi Lilik Hasanah +3 位作者 Dadi Rusdiana Fatimah A. Noor Neny Kurniasih Khairurrijal 《半导体学报:英文版》 EI CAS CSCD 2019年第6期43-47,共5页
The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like... The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrodinger’s equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method(TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrodinger’s equation. 展开更多
关键词 graphene NANORIBBON TUNNEL field effect transistor tunneling current SCHRODINGER EQUATION Dirac-like EQUATION
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产业政策、盈余信息质量与审计意见 预览
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作者 曾慧宇 《商业经济与管理》 CSSCI 北大核心 2019年第6期82-96,共15页
宏观经济政策对微观企业行为影响是当前经济和管理学领域的一个热点话题。文章以2006—2015年沪深两市A股上市公司为样本,理论分析与实证检验了宏观产业政策对微观企业审计意见的影响及其内在机理。实证结果发现,产业政策显著降低了受... 宏观经济政策对微观企业行为影响是当前经济和管理学领域的一个热点话题。文章以2006—2015年沪深两市A股上市公司为样本,理论分析与实证检验了宏观产业政策对微观企业审计意见的影响及其内在机理。实证结果发现,产业政策显著降低了受支持企业被出具非标准审计意见的概率,并且路径分析揭示,产业政策对审计意见的影响通过提高受支持企业的盈余信息质量得以实现,在通过双重差分(DID)控制潜在的内生性之后,仍表明产业政策能显著提高受支持企业的盈余信息质量。进一步探究其内在机理发现,产业政策会降低受支持企业的融资约束程度,从而降低企业市场融资动机下的盈余操纵行为,进而提升其盈余信息质量;同时产业政策会通过降低受支持企业大股东的掏空行为,从而降低其为掩盖掏空而进行的盈余操纵,进而提升盈余信息质量。这些发现揭示了产业政策影响审计意见的内在机理,不但为产业政策的积极经济后果提供了支持证据,也丰富了审计意见研究的相关理论。 展开更多
关键词 产业政策 审计意见 盈余信息质量 融资约束 大股东掏空
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儒家文化与上市公司“隧道效应” 预览
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作者 叶德珠 李鑫 《金融发展研究》 北大核心 2019年第5期3-12,共10页
传统“儒商精神”提倡要“以义取利”、关注利益相关者的利益和积极承担社会责任,一定程度上可以减少企业实施不道德的商业行为。本文以2006-2017年中国上市公司为研究对象,使用GLOBE文化习俗指数中的“社会导向的集体主义”“不确定性... 传统“儒商精神”提倡要“以义取利”、关注利益相关者的利益和积极承担社会责任,一定程度上可以减少企业实施不道德的商业行为。本文以2006-2017年中国上市公司为研究对象,使用GLOBE文化习俗指数中的“社会导向的集体主义”“不确定性规避”“未来导向”作为度量儒家文化的替代指标,进而考察儒家文化对上市公司实施“隧道效应”的影响。结果发现:上市公司受到儒家文化的影响越大,实施的隧道效应越小,并且这种负相关性在民营企业中更为明显。此外,我们还发现在对外开放程度较高和儒家文化破坏程度较高的地区,儒家文化缓释“隧道效应”的作用会有所减弱。本文拓展了非正式制度对公司治理的影响方面的研究,丰富了“文化金融学”相关理论。 展开更多
关键词 隧道效应 儒家文化 对外开放度 非正式制度 文化金融学
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股利折价之谜--基于大股东掏空与监管迎合的探索
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作者 马鹏飞 董竹 《南开管理评论》 CSSCI 北大核心 2019年第3期159-172,共14页
本文以2008-2015年我国沪深两市A股上市公司为研究样本,构建"股利支付动机-股利价值效应-股利折价"的分析路径,从大股东掏空与监管迎合视角分析中国"股利折价之谜"。研究发现,当大股东利用现金股利掏空公司时,中小... 本文以2008-2015年我国沪深两市A股上市公司为研究样本,构建"股利支付动机-股利价值效应-股利折价"的分析路径,从大股东掏空与监管迎合视角分析中国"股利折价之谜"。研究发现,当大股东利用现金股利掏空公司时,中小投资者倾向退出投资,股利支付公司的价值受损,形成股利折价;但监管迎合动机下的现金股利反而对公司价值存在正向效应,表明投资者认同上市公司迎合监管行为,监管迎合不是股利折价根源。进一步分析发现,大股东还可能将监管迎合作为掩饰其掏空的"面具"。本文首次对"股利折价之谜"进行分析并对其根源精准定位,揭示监管政策的积极作用,反对以往"监管悖论"观点;同时提出未来监管政策应重点关注大股东掏空,提高股利支付公司的价值。 展开更多
关键词 现金分红 股利折价 大股东掏空 公司价值 监管悖论
软岩巷道掘进及支护技术应用与实践 预览
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作者 钮磊 《当代化工研究》 2019年第3期91-92,共2页
山西某矿1201运输巷是典型的软岩巷道,巷道掘进困难。基于此,笔者以1201运输巷掘进为工程背景,在分析制约巷道掘进因素的基础上从优化掘进机截割方式、软弱底板解决措施、巷道冒顶解决措施等方面提出了相关的解决措施,并根据巷道围岩特... 山西某矿1201运输巷是典型的软岩巷道,巷道掘进困难。基于此,笔者以1201运输巷掘进为工程背景,在分析制约巷道掘进因素的基础上从优化掘进机截割方式、软弱底板解决措施、巷道冒顶解决措施等方面提出了相关的解决措施,并根据巷道围岩特征提出了管棚超前支护+注浆支护+喷浆支护的联合支护措施。应用实践表明,巷道单月掘进进尺从100m提升到260m,巷道掘进速度大幅提升,为矿井安全高效生产创造了有利条件。 展开更多
关键词 软岩巷道 掘进 支护
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基于排队论的中硬围岩长大隧道施工机群优化配置方法 预览
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作者 曹豪荣 彭立敏 +2 位作者 杜昆 雷明锋 刘瑶 《铁道科学与工程学报》 CAS CSCD 北大核心 2019年第2期535-541,共7页
针对隧道施工过程中各作业线内部产生的机械排队作业现象,采用随机过程排队论方法以Ⅲ级围岩为例研究中硬围岩长大隧道施工循环作业线中机械配套问题,提出顾客为有限源的M/M/1/m/m排队系统的求解方法,由此得到基于快速施工的最优机械配... 针对隧道施工过程中各作业线内部产生的机械排队作业现象,采用随机过程排队论方法以Ⅲ级围岩为例研究中硬围岩长大隧道施工循环作业线中机械配套问题,提出顾客为有限源的M/M/1/m/m排队系统的求解方法,由此得到基于快速施工的最优机械配套方案。结合黄岩隧道妹子娘冲斜井段的工程实例,得到Ⅲ级围岩下出碴运输系统以及锚喷支护系统的最优配置,可为工程实际施工提供一定参考。 展开更多
关键词 隧道施工 排队系统 快速施工 机械配套 最优配置
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Optimization of ambipolar current and analog/RF performance for T-shaped tunnel field-effect transistor with gate dielectric spacer
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作者 韩茹 张海潮 +1 位作者 王党辉 李翠 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期656-662,共7页
A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics ... A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics such as current-voltage relationships, energy band diagrams, band-to-band tunneling(BTBT) rate and the magnitude of the electric field are investigated by using TCAD simulation. It is found that compared with conventional TTFET and TTFET with gate-drain overlap(GDO) structure, GDS-TTFET not only has the minimum ambipolar current but also can suppress the ambipolar current under a more extensive bias range. Furthermore, the analog/RF performances of GDS-TTFET are also investigated in terms of transconductance, gate-source capacitance, gate-drain capacitance, cutoff frequency, and gain bandwidth production. By inserting a low-κ spacer layer between the gate electrode and the gate dielectric, the GDS structure can effectively reduce parasitic capacitances between the gate and the source/drain, which leads to better performance in term of cutoff frequency and gain bandwidth production. Finally, the thickness of the gate dielectric spacer is optimized for better ambipolar current suppression and improved analog/RF performance. 展开更多
关键词 tunneling field effect TRANSISTOR T-SHAPED TUNNEL FIELD-EFFECT TRANSISTOR gate dielectric SPACER ambipolar current analog/RF performance
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