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1.
提出了SiGe和SiGeC异质结晶体管基区渡越时间的一种闭式物理模型,该模型考虑了电子温度效应.计入薄基区内强电场(该电场源起于Ge,C元素的掺杂)引起的电子温度变化,得到的基区渡越时间值与漂移-扩散模型有所不同.随着Ge含量的增加,两者的差别不能再忽略.  相似文献   

2.
讨论了采用能量传输模型时的SiGeHBT基区电子温度分布,以及电子温度对基区渡越时间的影响.计算结果表明:基区电子温度呈现明显的不均匀分布,从发射极侧到集电极侧逐渐增大;电子温度分布主要由基区Ge分布决定,而基区掺杂对电子温度的影响不大.考虑基区电子温度分布时基区渡越时间减小,在较大的Ge分布梯度下,电子温度对基区渡越时间的影响不可忽略.  相似文献   

3.
在Si1-ZGeZ基区HBT中,Ge组份Z缓变(进而能隙缓变)产生自建电场,基区杂质浓度向发射极侧的减小产生了阻滞电场,基区杂质浓度向集电极侧的减小产生了加速电场.文中研究了这些电场对基区渡越时间的影响.研究结果表明,随基区发射极侧杂质浓度的不同,因阻滞电场而产生的延迟时间占基区总渡越时间的40%~80%.同时还发现,选用无阻滞电场产生的基区杂质分布,采用大的Ge组份线性缓变和利用集电结空间电荷区电子速度过冲效应,可望得到截止频率大于100GHz的Si1-ZGeZ基区HBT  相似文献   

4.
在Si1-zGez基区HBT中,Ge组份Z缓变产生自建电场,基区杂质浓度向发射极侧的减小产生了阻滞电场,基区杂质浓度向集电极侧的减小产生了加速电场。文中研究了这些电场对基区渡越的影响,研究结果表明,随基区发射极侧杂质浓度的不同,因阻滞电场而产生的延迟时间占基区总渡越时间的40% ̄80%。同时还发现,选用无阻滞电场产生的基区杂质分布,采用大的Ge组份线性缓变和利用集电结空间电荷区电子速度过冲效应,可  相似文献   

5.
按比例缩小SiGe HBT能量传输模型   总被引:1,自引:0,他引:1  
针对用传统的漂移扩散模型分析小尺寸SiGe HBT的局限性,采用新的能量传输模型.通过分析建立了小尺寸SiGe HBT(考虑Ge含量)的玻尔兹曼方程,得到不同区域电子温度的分布;并比较了不同基区宽度、不同Ge梯度下的电子温度曲线.结果发现在基区很薄的情况下,电子从基区向集电区渡越时,其温度逐渐升高,且大大高于晶格温度,且不同基区宽度基区电子温度变化率不同.  相似文献   

6.
本文考虑禁带变窄效应和载流子冻析效应,分析了基区掺杂浓度的分布、基区峰值浓度的大小及位置对基区渡越时间的影响,结合基区电阻的温度模型,对低温度高速双极晶体管的优化设计作了探讨。  相似文献   

7.
利用多晶硅发射极技术与分子束外延生长SiGe基区技术相结合,研制成适于集成的平面结构、发射结面积为3?μm×8?μm的SiGe异质结双极晶体管(HBT)。室温下该晶体管的直流电流增益β为30到50,基极开路下,收集极-发射极反向击穿电压BVCEO为5?V,晶体管的截止频率fT为13.5?GHz。  相似文献   

8.
采用一维有限差分方法,对生长在Si(001)衬底上的Si0.8Ge0.2应变基区异质结双极晶体管(HBT)与Si同质结双极晶体管(BJT)的直流特性进行了数值分析;给出了高斯掺杂情形下,基区中Ge含量为0.2的Si0.8Ge0.2HBT与Si同质双极结晶体管(BJT)的共射极电流放大系数图、Gummel图、平衡能带图和基区少子分布图,对比结果表明基区中Ge的引入有效地改善了晶体管的直流放大性能;其次对Si0.8Ge0.2HBT与SiBJT的大电流特性进行了比较,证实了在大电流下异质结基区少子向集电区扩展引起的异质结势垒效应,使Si0.8Ge0.2HBT的直流放大系数比SiBJT的放大系数下降更快这一实验结果.  相似文献   

9.
构建了一个SiGe异质结双极NPN晶体管的物理模型.在分析异质结双极晶体管工作机理的基础上,利用ISE_TCAD软件模拟了Si1-xGex中的Ge组分对器件反向击穿特性的影响.结果表明:在其他参数相同的情况下,增加Ge组分虽可增加晶体管的电流增益,但可导致晶体管的耐压降低,BVcbo、BVceo、BVebo等击穿电压均随x组分的增加而减少.本研究对利用软件实现器件的虚拟制造、以及设计中如何进行合理的组分剪裁从而获取综合性能的优化有一定意义.  相似文献   

10.
具有重掺杂基区和中等掺杂发射区的硅赝异质结双极晶体管,其能带结构类似于真实异质结双极晶体管的能带结构。本文研究了硅赝质结双极晶体管的电流增益,截止频率和基区电阻等电学参数性能及其与温度的关系。并指出了硅赝异质结双极晶体管在低温下应用的潜力。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

18.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

19.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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