双补偿p-n结GaAs红外发光二极管

双补偿p-n结(即p-n结两边均为两性杂质所补偿)发光二极管具有p-i-n三重结构。这种发光二极管的主要特点是具有较高的外量子效率。因为si在GaAs中是两性杂质,我们用液相外延法,在GaAs中掺Si制成双补偿p-n结GaAs红外发光二极管。其发光外量子效率比其他几何形状相近的二极管有明显的提高。较好的半球型发光二极管在没镀增透射膜(Si0)的情况下,外量子效率达到了15％。这种双补偿p-n结是用液相外延法,在生长过程中由于温度的降低Si在GaAs中转型而形成的.在开始生长温度较高时Si占据Ga的位置,形成n型层,当温度较低时Si就占据As的位置,因此大约在低于850℃时外延生长层为p型层。     

高速Ge光电探测器脉冲和频率响应的特性测量

本文用电光采样技术测量了高速Ge雪崩光电二极管的脉冲响应特性,利用计算机进行快速傅里叶变换(FFT)运算,得到了探测器的频率响应曲线。     

Ar~ 离子注入对Ge/GaAs(100)异质结能带偏离影响的XPS研究

用X光电子能谱(XPS)方法研究了界面特性和Ge/GaAs(100)异质结的能带偏离关系。实验表明,当在清洁的GaAs(100)表面生长Ge异质结时,其价带偏离(△E_v)与界面特性无关,而在Ar离子注入的GaAs(100)表面上生长的Ge异质结,其价带偏离与Ar~ 离子的浓度分布有关。     

拓扑绝缘体Bi2Se3光电性能研究

文章基于分子束外延法(molecular beam epitaxy,MBE)制备高质量的硒化铋(Bi_2Se_3)薄膜,运用反射式高能电子衍射仪(reflection high-energy electron diffraction,RHEED)表征样品的生长质量。在Bi_2Se_3和Ge上将蒸镀铟(In)电极和银(Ag)电极分开,并将其制成肖特基结光电探测器,据此测量了样品在不同波长激光和不同温度下的光响应特性及低温对样品的影响,并通过计算样品的响应度、开关比、探测率等参数分析了拓扑绝缘体在光电探测方面的应用前景。     

锗锡薄膜的分子束外延生长及退火研究

无应变锗锡(GeSn)合金在Sn的摩尔组分高于8%时能够转变为直接带隙材料，适合于制备硅基光电子器件.分子束外延(MBE)在高纯度GeSn制备、Sn组分和异质界面的精确调控上具有巨大的优势.然而，由于Sn在Ge中的固溶度低(<1%)、Ge与α-Sn晶格失配大(约14.7%),高Sn组分、应变弛豫直接带隙GeSn薄膜材料的MBE制备仍是一个巨大的挑战.本文综述了MBE制备高Sn组分GeSn薄膜及弛豫GeSn薄膜压应变的相关研究.首先介绍了低温MBE技术外延高Sn组分GeSn薄膜的方法及生长应变弛豫GeSn薄膜的挑战.之后给出GeSn薄膜的快速热退火行为与厚度的依赖关系，基于临界厚度模型捋清了退火过程中GeSn薄膜的应变弛豫与Sn偏析的竞争机制；最后介绍了快速热退火对GeSn薄膜发光特性的影响，提出采用快速热退火制备应变弛豫的Sn组分渐变GeSn异质结，通过载流子自限制增强MBE生长GeSn薄膜的光致发光强度.     

采用低温缓冲层技术在Si衬底上外延生长Ge薄膜

利用超高真空化学气相淀积系统,在Si(100)衬底上外延采用低温缓冲层技术外延生长Ge薄膜。实验测试得到外延Ge的X射线双晶衍射曲线半高宽为537arc sec,应变为0.2%。在室温下观测到外延Ge的直接带跃迁光致发光,发光峰位为1560 nm,表明生长的Si基Ge材料具有良好的质量。     

用激光分子束外延在Si衬底上外延生长La1-xSrxMnO3单晶薄膜

采用SrO和SrTiO3作为缓冲层, 用激光分子束外延在Si (100)衬底上成功地外延生长出La_1-xSr_xMnO₃ (x=0.1, 0.2, 0.3) (LSMO)单晶薄膜. 锐而清晰的反射式高能电子衍射仪 (RHEED)的衍射条纹和持久的RHEED强度振荡, 表明LSMO薄膜是很好的二维层状外延生长. X射线衍射和高分辨透射电镜分析结果证明, 在Si基底上获得了很好外延生长的LSMO薄膜, LSMO薄膜为C取向的单晶薄膜. 并在室温条件下观测到很好的LSMO/Si p-n结I-V整流特性.     

PIN光电探测器用反外延片工艺研究

创新性使用反外延法工艺,介绍了适用于制备近红外波段PIN光电探测器的硅外延材料的研制工艺,在区熔单晶抛光片上进行重掺导电层和支撑层的外延层制备。通过对硅源流量与掺杂剂浓度的精确控制,实现了快速外延生长和高浓度掺杂。通过精细的后期加工工艺,将高阻区熔层加工为厚度和表面质量均满足器件要求的有源层。结果显示,采用反外延法工艺得到的反外延材料片应用到PIN光电二极管中,不仅节省器件制备中的工艺程序,而且大大提高了器件耐压性。     

液相外延掺氮磷化镓绿色发光材料

引言磷化镓是目前主要采用的绿色发光材料。国外对于汽相外延制取此材料作了不少努力,但目前效率最高的材料是由液相外延形成p-n生长结而制得的。我们为了获得优质的绿色发光材料,选取了液相外延;同时为了提高产量,在试用双池法之后也采用过一次外延加扩散的办法,还采用过薄熔料过补偿法。将这三种方法制得的p-n结材料制成的发光二极管进行比较时发现,双池法和过补偿法做的p-n生长结均可获得好的亮     

光接收机的宽带前置放大器

在光接收机中,人们通常把用作检测光缆传来的高频光信号的光检测器(由PIN管或者雪崩光电二极管组成)和前置放大器设计在一起。为了保证宽频带光信号的接收,就要求这种放大电路具有频带宽、线性好、增益高和信噪比亦高的特性。目前,性能最好的一种电路结构是:用雪崩光电二极管作光检测器,以砷化镓场效应管作前置放大器,并把电路设计为互阻抗放大器的形式。然而,雪崩光电二极管价格昂贵,场效应管,特别是低容值的砷化镓场效应管     

Markedness and its Interpretation in Language Use

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

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.     

Features of Women's language

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

低渗透非均质砂岩油藏启动压力梯度研究

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

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.     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.