Heterojunction solar cells with n-type nanocrystalline silicon emitters on p-type c-Si wafers

Hydrogenated nanocrystalline silicon (nc-Si:H) n-layers have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) wafers. The nc-Si:H n-layers were deposited by radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD), and characterized using Raman spectroscopy, optical transmittance and activation energy of dark-conductivity. The nc-Si:H n-layers obtained comprise fine grained nanocrystallites embedded in amorphous matrix, which have a wider bandgap and a smaller activation energy. Heterojunction solar cells incorporated with the nc-Si n-layer were fabricated using configuration of Ag (100 nm)/1T0 (80 nm)/n-nc-Si:H (15 nm)/buffer a-Si:H/p-c-Si (300 mu m)/Al (200 nm), where a very thin intrinsic a-Si:H buffer layer was used to passivate the p-c-Si surface, followed by a hydrogen plasma treatment prior to the deposition of the thin nanocrystalline layer. The results show that heterojunction solar cells subjected to these surface treatments exhibit a remarkable increase in the efficiency, up to 14.1% on an area of 2.43 cm(2). (c) 2006 Elsevier B.V. All rights reserved.

Donor defect in P-diffused bulk ZnO single crystal

A high concentration of shallow donor defect is formed in P-diffused ZnO single crystals. X-ray photoelectron spectroscopy analysis indicates that P atom occupy different lattice site at different diffusion temperature. Nature of the donor defect has been discussed.

Self-heating effect in 1.3 mu m p-doped InAs/GaAs quantum dot vertical cavity surface emitting lasers

The self-heating effect in 1.3 mu m p-doped InAs/GaAs quantum dot (QD) vertical cavity surface emitting lasers (VCSELs) has been investigated using a self-consistent theoretical model. Good agreement is obtained between theoretical analysis and experimental results under pulsed operation. The results show that in p-doped QD VCSELs, the output power is significantly influenced by self-heating. About 60% of output power is limited by self-heating in a device with oxide aperture of 5x6 mu m(2). This value reduces to 55% and 48%, respectively, as the oxide aperture increases to 7x8 and 15x15 mu m(2). The temperature increase in the active region and injection efficiency of the QDs are calculated and discussed based on the different oxide aperture areas and duty cycle.

Improved electroluminescence from n-ZnO/AlN/p-GaN heterojunction light-emitting diodes

n-ZnO/p-GaN heterojunction light-emitting diodes with and without a sandwiched AlN layer were fabricated. The electroluminescence (EL) spectrum acquired from the n-ZnO/p-GaN displays broad emission at 650 nm originating from ZnO and weak emission at 440 nm from GaN, whereas the n-ZnO/AlN/p-GaN exhibits strong violet emission at 405 nm from ZnO without GaN emission. The EL intensity is greatly enhanced by inserting a thin AlN intermediate layer and it can be attributed to the suppressed formation of the GaOx interfacial layer and confinement effect rendered by the AlN potential barrier layer.

P-QuantWiz:一种基于质谱的并行非标记定量软件

本文设计并实现了基于质谱的非标记定量软件QuantWiz,通过改变肽段定量的顺序,提高了定量软件的时间局部性和质谱数据缓存的命中次数。分析了QuantWiz的多种数据并行策略,设计并实现了按保留时间划分的并行定量软件P-QuantWiz。通过实验验证P-QuantWiz具有良好的并行效率,当进程数为32时,并行效率为63%。

on string languages generated by spiking neural p systems

We continue the study of spiking neural P systems by considering these computing devices as binary string generators: the set of spike trains of halting computations of a given system constitutes the language generated by that system. Although the "direct" generative capacity of spiking neural P systems is rather restricted (some very simple languages cannot be generated in this framework), regular languages are inverse-morphic images of languages of finite spiking neural P systems, and recursively enumerable languages are projections of inverse-morphic images of languages generated by spiking neural P systems.

用不对称的P/V操作设计并发算法

多线程并发是提高系统性能的常用手段,文章提出了一种用信号量的不对称P/V操作来设计多线程并发算法的新思路,这种思路适合于设计多线程同步程序以解决某些具有复杂同步语义要求的问题,而这些问题用传统的方法很难得到简洁高效的求解。为了演示这种新思路的特点和优点,笔者对几个常见问题(读写锁、排队锁和记录锁)给出了新的算法设计以及实现。实验数据表明,采用这种思路设计的算法在算法复杂度,读写速度和资源使用方面相对于传统的算法存在较大优势。

P-RBAC:一种门户环境下的访问控制模型

门户能够有效地实现异构信息之间的集成与协作,并为用户提供可定制、统一且遵循规范的访问服务.然而,由于门户所具有的这些不同于普通Web应用的特性,也使得传统访问控制模型无法在门户中直接使用.提出了一种面向门户系统的访问控制模型p-RBAC.P-RBAC扩展了传统的基于角色访问控制模型,并根据行为状态进一步分为静态模型和动态模型.P-RBAC给出了静态模型和动态模型上的行为规则,提出了具体的动态权限指派和角色组织策略,从而有效地解决了门户的访问控制问题.实际的应用案例证明,P-RBAC模型能够适用于门户的访问控制,并较之传统访问控制模型更高效可行.

环烷酸和其它萃取剂协同萃取稀土元素的化学

环烷酸是一种价廉容量大的萃取剂，在其中加入混合醇工业上已用于分离制取高纯Y_2O_3，并用于提纯氧化铕。为了扩大环烷酸的应用，我们对加有中性磷萃取剂及β－双酮类螯合剂的环烷酸协萃体系进行了较为系统的研究。测定了协萃体系萃取Nd(III)和Er(III)的协萃曲线，协萃剂的协萃能力强弱顺序为：PMBP＞TOPO＞BDBP＞DBBP＞TBP Er(III)＞Nd(III) TBP几乎没有协萃效应，当其在有机相中所占克分子而分数大于30％时，尤其如此，DBBP有类似的规律，其余协萃剂均无反协萃效应。测定单一稀土离子分配比随原子序数的变化可见协萃体系协萃重稀土的能力大于轻稀土。钇的萃取位置发生了显著的变化，主要是位于轻稀土组，在如有DBBP及TOPO的体系中移至了HO附近；随着平衡水相酸度的降低，钇有向原子序数增大的方向移动的趋势，而且中性磷萃取剂的萃取能力越大，钇的萃取位置变化越多，使其和镧系元素之间的分离因素有所下降。用解析法等研究了多元协萃络合物的组成及协萃反应机理，并计算了相应的表观协萃平衡常数及有机相加合反应平衡常数。考察萃取前后有机相的红外光谱可见中性磷萃取剂和环烷酸形成氢键的能力为：TBP＞DBBP＞BDBP＞TOPO和金属离子的配位能力为：TBP＜DBBP＜（BDBP）＜TOPO Nd(III)＜Er(III)找出了环烷酸配位后羧基的反对称及对称伸展振动，由二者之差指出羧基为螯合配位或双金属格式配位，P＝O和金属离子形成了配价键。游离中性磷化合物，混合有机相中及协萃络合物中的P＝0伸展振动波数与其诱导效应指数之间符合线性规律。将中性磷化合物单独萃取Nd(III)及Er(III)时的分配比，协萃体系的总分配比，酸性协萃系数，表现协萃平衡常数及有机相加合反应平衡常数的对数对P＝0伸展振动频率及诱导效应指数作用，也能找到近似的线性规律。分析环烷酸和PMBP混合前后的振动光谱及换磷共根~1H谱发现环烷酸和PMBP之间也有氢键律合作用。为了进一步说明协萃剂在萃取过程中的作用，合成了除Pm以外十五个稀土－PMRP－环烷酸三元络合物。用快原子轰出质谱法测定了La、Pr及Er等元素络合物的分子量。络合物TG－DTA曲线表明分解过程分两步进行，第一步为环烷酸的分解，第二步为PMBP的分解，最后产物为氧化物。环烷酸首先分解是由于环烷酸和稀土离子的键合强度不如PMBP，这在络合物的质谱，~1HNMR谱及恒温产物的红外光谱中均得到了证实，系统地研究了络合物在4000－100cm~(-1)范围内的FT－IR艺谱，分析了配体和稀土离子配位前后，COOH，ezo, c…e…c及RE－O等振动附近的变化，指出了配体和稀土离子之间的配位形式可能为：PMBP和稀土离子形成的RE－O键伸展振动频率可分为轻重稀土组，环烷酸和稀土离子之间的RE－O键伸展振频率与稀土离子总轨道角动量之间符合斜“W”规律，为常数和原子序数之间呈现近似“四分组”效应，钇位于Lu前，并接近于Lu。还考察了络合物~1HNMR谱上配体的各种基团质子化学位移，指出络合物可能有两种空间模型。在所形成的化合物中，Ce呈现四价状态为Ce(PMBP)_2A_2，其稳定性大于其他三价稀土离子的络合物。