还原再氧化型半导体陶瓷电容器材料的研究

通过实验研究了Ｎｄ２Ｏ３、Ｎｂ２Ｏ５、Ｓｍ２Ｏ３添加量对还原再氧化型ＢａＴｉＯ３半导体陶瓷电容器材料性能的影响，同时优化了烧结工艺，获得了Ｃ＞０．５μＦ／ｃｍ２，ｔｇδ＜３．５×１０－２，ρ＞４×１０１１Ω·ｃｍ，｜△Ｃ／Ｃ｜（－２５～＋８５℃）＜＋３０－８０％，Ｖｂ＞４２０Ｖ的实用半导体陶瓷电容器材料     

用XPS对CdTe（111）面进行化学特性分析

用ＸＰＳ化学位移和定量分析方法，研究了露于室温空气中的ＣｄＴｅ（１１１）面的化学特征。首次报道了经机械抛光表面上形成的表面化合物为ＴｅＯ２（Ｔｅ３ｄ５／２５７５．８ｅＶ，Ｏ１ｓ５３０．１ｅＶ）和Ｃｄ（ＯＨ）２（Ｃｄ３ｄ５／２４０５１ｅＶ．Ｏ１ｓ５３１．４ｅＶ）。并与基体里的ＣｄＴｅ共存；经２％Ｂｒ－乙醇溶液化学抛光，表面上形成的化合物为ＣｄＴｅＯ４（Ｃｄ３ｄ５／２４０５．３ｅＶ，Ｔｅ３ｄ５／２５７６５ｅＶ，Ｏ１ｓ５３１．２ｅＶ）和ＴｅＯｘ（ｘ＜１）（Ｔｅ３ｄ５／２５７４～５７５ｅＶ，Ｏ１ｓ５２８１ｅＶ），并且ＸＰＳ谱中没有基体里的ＣｄＴｅ的特征，其中ＴｅＯＸ为Ｔｅ氧化物的过渡态。结果表明，在相同氧化环境中，表面上形成的化合物强烈依赖表面状况。     

硅表面清洗对热氧化13nm SiO_2可靠性的影响

实验研究表明热生长１３ｎｍ薄ＳｉＯ２的可靠性同氧化前硅表面清洗处理方法有很大关系．氧化前稀ＨＦ酸及ＨＦ／乙醇漂洗不会提高热氧化薄ＳｉＯ２的可靠性;氧化前用ＮＨ４ＯＨ／Ｈ２Ｏ２／Ｈ２Ｏ（０．０５∶２∶５）溶液清洗形成化学预氧化层对提高薄ＳｉＯ２可靠性很有效;用Ｈ２ＳＯ４／Ｈ２Ｏ２（３∶１）溶液清洗形成预氧化层的改善作用也较明显,在之前增加比例为０．０５∶２∶５或１∶２∶５的ＮＨ４ＯＨ／Ｈ２Ｏ２／Ｈ２Ｏ溶液清洗和稀ＨＦ酸漂洗效果更好．另外,薄栅介质抗电离辐射性能和抗热电子损伤能力同氧化前形成化学预氧化层的清洗     

高T_cPTC陶瓷材料的配方研究

选用国产原材料，在（Ｂａ０．３Ｐｂ０．７）ＴｉＯ３＋４％ＡＳＴ＋０．０８％Ｍｎ（ＮＯ３）２材料中，添加（０．２～０．４）％（Ｎｂ２Ｏ５＋Ｙ２Ｏ３）＋０．２％ＢＮ＋（３～５）％ＣａＴｉＯ３（全为摩尔比）。采用传统陶瓷工艺，经１１５０℃适当烧结，可获得ρ２５ｃ≤１０４Ω·ｃｍ，Ｔｃ≥３８０℃，ρｍａｘ／ρｍｉｎ≥１０３，Ｖｂ≥６５０Ｖ的实用高ＴｃＰＴＣ陶瓷材料。     

硅分子束外延中硼δ掺杂生长研究

利用硅分子束外延技术和Ｂ２Ｏ３掺杂源，成功地实现了硅中的硼δ掺杂，硼δ掺杂面密度ＮＢ可达３．４e１４ｃｍ－２（１／２单层）以上，透射电镜所示宽度为１．５ｎｍ．我们首次用原位俄歇电子能谱（ＡＥＳ）对硼在Ｓｉ（１００）表面上的δ掺杂行为进行了初步的研究，发现在ＮＢ＜３．４e１４ｃｍ－２时，硼δ掺杂面密度与时间成正比，衬底温度６５０℃，掺杂源温度９０００℃时，粘附速率为４．４e１３ｃｍ－２／ｍｉｎ；在ＮＢ＞３．４e１４ｃｍ－２时，粘附有饱和趋势，测量表明在硼δ掺杂面密度ＮＢ高达４．４e１４ｃ     

He－Ne激光对玉米幼苗活性氧代谢的影响

用功率密度为２．８ｍＷ／ｍｍ２，３．８ｍＷ／ｍｍ２及５．４ｍＷ／ｍｍ２的Ｈｅ－Ｎｅ激光辐射干种子，辐射时间均分别为５，５０和５００ｓ。发现经激光辐射干种子的玉米幼苗中，过氧化物酶（ＰＯＤ）和过氧化氢酶（ＣＡＴ）活性均增高，抗坏血酸过氧化物酶（ＡｓＡＰＯＤ）活性下降，谷光甘肽（ＧＳＨ）含量增加。其综合效果是增强了植物体清除活性氧的能力。     

ErYb：氟氧化物玻璃在966nm激光激发下的能量“扩散—传递”上转 …

频率上转换的研究是光物理学科的热点前沿课题．本文研究的是 Ｅｒ（１ｍｏｌ％） Ｙｂ（１０ ｍｏｌ％）共掺的 ＳｉＯ２－ＡｌＯ１．５－ＰｂＦ２－ＣｄＦ２氟氧化物玻璃（ＥｒＹｂ：ＹＯＧ）样品的直接上转换敏化发光机制． 首先测量了在激光焦点ａ处和较大光斑位置ｂ处的上转换发光,发现有丰富的上转换荧光．其中较强的有（６６５．５ ｎｍ, ６５３．５ｎｍ）,（５４９．０ ｎｍ, ５４２．５ ｎｍ）和（５２１．５ ｎｍ, ５２７．０ ｎｍ）三条荧光线,容易指认出它们依次分别是４Ｆ９／２－４Ｉ１５／２,４Ｓ３／２－４Ｉ１５／…     

YBa_2Cu_3O_（7－δ）高温超导薄膜微桥结在微波辐照下的响应特性

采用偏轴宜流磁控溅射原位生长ＹＢａ２Ｃｕ３Ｏ７－δａ高温超导薄膜，以Ｈ３ＰＯ４为腐蚀液，采用化学湿刻工艺制作ＹＢａ２Ｃｕ３Ｏ７－δ高温超导薄膜微桥，微桥长１０μｍ，宽５μｍ，在８ｍｍ微波源的辐照下，除观察到整数常压台阶外，还观察到ｎ＝１／２，１／５，６／５，９／５等分数常压台阶，分数台阶的高度随微波功率的变化较整数台阶更敏感．     

国产设备高山微波站无人值守建设,管理的探讨

根据两年的多因素旋转回归设计试验资料，按不同降水年份，对陕西渭北旱塬小麦的高产栽培的优化模式进行了研究。结果表明，试验中各因素对小麦产量影响的顺序为：氮肥＞播期＞密度＞磷肥。不同的降水年份，小麦高产栽培的优化方案不同。干旱年份，要适期晚播、合理密植、重施磷肥少施氮肥，亩产高于２００ｋｇ的方案是；播期是９月２６－３０日、密度１７．５－２０万苗／亩、Ｎ７－９．５ｋｇ／亩、Ｐ２Ｏ５７．５－１０．５ｋｇ／     

YBa2Cu3O7—δ高温超导薄膜微桥结在微波辐照下的响应特性

采用偏轴直流磁控溅射原位生长ＹＢａ２Ｃｕ３Ｏ７－δ高温超导薄膜，以Ｈ３ＰＯ４为腐蚀液，采用化学湿刻工艺制作ＹＢａ２Ｃｕ３Ｏ７－δ高温超导薄膜微桥，微桥长１０μｍ，宽５μｍ，在８ｍｍ微波源的辐照下，除观察到整数常压台阶外，还观察到ｎ＝１／２，１／５，６／５，９／５等分数常压台阶，分数台阶的高度随微波功率的变化较整数台阶更敏感。     

On the Capacity of IEEE 802.11 DCF with Capture in Multipath-Faded Channels

In this paper, we estimated the influence of capture effect over the capacity of IEEE 802.11b DCF within a single picocell. The channel utilization is examined analytically by introducing two capture models based on Rayleigh-distributed envelopes of the captured and the interfering frames divided into two local-mean power classes. Simulations in a pure Rician-faded channel depict the conditions under which both Rayleigh-faded capture models can be used to accurately predict the peak network capacity. Unlike the RTS/CTS handshake access mode, Basic access mode is significantly sensitive to the capture ratio, i.e., the receiver design. The packet size threshold over which it is convenient to switch from Basic to RTS/CTS handshake access scheme is also sensitive to the capture effect.     

Ellipsometric Characterization of the Transition Layer in SiC/AlN Structures

An ellipsometric method to determine the thickness of the transition layer in SiC/SiO₂ structures is presented. It consists in solving the inverse problem of ellipsometry with as few as one or two unknowns. A technique to identify the polarity of (0001) SiC faces from and is proposed.     

Multicast capacity and delay trade‐offs in ad hoc networks with random iid mobility model

In this paper, multicast capacity and delay trade‐offs of mobile ad hoc networks are considered under random independently and identically distributed (iid) mobility model. Compared with unicast, multicast can reduce the overall network load by a factor with high probability (whp) in static random ad hoc networks, where k is the number of destination nodes in a multicast session. So we firstly discuss whether the law still holds in mobile random ad hoc networks, and in this case what delay should be tolerated. Through the relation between average retransmissions and multicast capacity, we prove that order of multicast capacity is not achievable whp, and delay for multicast capacity is , where is the number of ad hoc nodes in the whole networks, and and c is a positive constant. Then achievable throughput whp is considered. The nearest neighbor transmission strategy is introduced by Grossglauser and Tse to achieve throughput which is so far the highest achievable unicast capacity. So the multicast capacity of mobile ad hoc networks under this strategy is studied. The analysis shows that under any multicast routing scheme based on the nearest neighbor transmission strategy, the upper bound on multicast capacity is whp. Then we propose a multicast routing and scheduling scheme by which mobile ad hoc networks can achieve throughput whp, and must tolerate total network delay. Copyright © 2009 John Wiley & Sons, Ltd.     

Multiple parallel concatenation of circular recursive systematic convolutional (Crsc) codes

This paper deals with a family of error correcting codes based on circular recursive systematic convolutional (Crsc) codes. A multiple or multidimensional parallel concatenation ofCrsc codes is proposed in order to reach minimum distances comparable to those of random codes. For information blocks of size k, minimum distances as large as k/4, for a 1/2 coding rate, may be obtained if the code dimension is raised to 4 or 5. Such codes can be decoded using an iterative (“turbo”) process relying on the extrinsic information concept.     

A Very High-Speed BiCMOS Replicating Current Comparator for Use in Viterbi Decoders

We describe a low power, asynchronous BiCMOS replicating currentcomparator (RCC) cell for use in analogue Viterbi decoders. The circuitemploys negative feedback to provide an accurate virtual ground for inputcurrent summation and comparison. Thus, although the circuit parasitics arecharged from the power supply as in the case of RCC's with positive feedback, no latching occurs. A resetphase is therefore not required and a more optimal combination of operating speed andresolution can be obtained. Post-layout simulations indicate that the circuit operates inexcess of 150 MHz, can resolve input currents differing by as little as 1A and has a dynamic range in excess of ±200 A. Estimated powerdissipation is about 5 mW per decoder state, drawn from a single 2.8 V powersupply.     

Mechanism of the Generation of Donor–Acceptor Pairs in Heavily Doped <Emphasis Type="Italic">n</Emphasis>-ZrNiSn with the Ga Acceptor Impurity

The nature of the mechanism of the simultaneous generation of donor–acceptor pairs under heavy doping of n-ZrNiSn intermetallic semiconductor with the Ga acceptor impurity is established. Such spatial arrangement in the crystal lattice of ZrNiSn_1–xGa _x is found when the rate of movement of the Fermi level εF found from calculations of the density distribution of electron states coincides with that experimentally established from dependences lnρ(1/T). It is shown that when the Ga impurity atom (4s²4p¹) occupies the 4b sites of Sn atoms (5s²5p²), structural defects of both acceptor nature and donor nature in the form of vacancies in the 4b site are simultaneously generated. The results are discussed in the scope of the Shklovskii–Efros model of a heavily doped and compensated semiconductor.     

Growth of 4H silicon carbide crystals on a (11 \bar 2 2) seed

The features of the defect structure of 4H silicon carbide ingots grown by the modified Lely method on (11 $ \bar 2 $ 2)-oriented seeds are studied. It is shown that this seed plane can be used to improve the structural quality of silicon carbide ingots. The defect structure of grown ingots features a complete lack of micropores and a decreased (by an order of magnitude) dislocation density in comparison with the seed. At the same time, growth on the (11 $ \bar 2 $ 2) seed results in stacking fault accumulation. The type of stacking faults corresponds to formula (5, 2) in the Zhdanov notation (internal Frank stacking fault).     

Capacity and Channel Coding for Wireless Point-to-Point <Emphasis Type="Italic">Z</Emphasis><Superscript>2</Superscript> Channel

In this paper, we derive the capacity of the asymmetric \({\text{Z}}^{2}\)-channel, which has been presented for the first time as an optimization problem. Similar to the Z-Channel, the proposed \({\text{Z}}^{2}\)-channel can be modelled as a practical interference wireless channel. In addition, the capacity behavior of \({\text{Z}}^{2}\)-channel is discussed and some examples and simulation results for the capacity is presented. Also a code plan has been applied for \({\text{Z}}^{2}\)-channel, based on repetition code to simulate its performance and compare it with the original Z-channel. In conclusion, simulation results show that the \({\text{Z}}^{2}\)-channel can be used widely for different operating points.