铜铟镓硒太阳能电池多层膜的结构分析

对于溅射后硒化和共蒸发等方法制备的铜铟镓硒（CIGS）太阳能电池薄膜,利用多种分析方法研究了CIGS多层膜的复杂结构等．研究表明：卢瑟福背散射（RBS）在分析CIGS多层膜方面具有其独特优势和可靠的结果;溅射后硒化方法制备的CIGS薄膜中,Ga和In在CIGS薄膜中呈梯度分布,这种Ga表层少而内层多的不均匀分布与Mo层没有必然关系;RBS和俄歇电子能谱分析（AES）均显示CIGS太阳能电池器件多层膜界面处存在扩散,尤其是CdS与CIGS,Mo与CIGS的界面处;X射线荧光（XRF）结果表明,电池效率最高的CIGS层中In,Ga比例为In：Ga=0．7：0.3;X射线衍射（XRD）结果显示：退火后的CIGS／Mo薄膜结晶品质得到了优化．     

Characterization of different-Al-content AlGaN/GaN heterostructures on sapphire

Al x Ga 1-x N/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the Al content up to 26% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2105 cm 2 /V s with a sheet carrier density of n s = 1.10 × 10 13 cm -2 , for a 26% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 Ω/□ has also been achieved.     

使用AlN/GaN超晶格势垒层生长高Al组分AlGaN/GaN HEMT结构

在蓝宝石衬底上生长了以AlN/GaN超晶格准AlGaN合金作为势垒的HEMT结构材料,并与传统AlGaN合金势垒样品进行了对比.在高Al组分(≥40%)情况下,超晶格势垒样品的表面形貌明显改进,电学性能特别是2DEG面电子浓度也有所改进.对超晶格势垒生长参数进行了初步优化,使得HEMT结构薄层电阻进一步降低,最后获得了251 Ω/□的薄层电阻. 关键词： AlGaN/GaN 结构 AlN/GaN超晶格 二维电子气 高电子迁移率晶体管     

Microstructure, bonding strength and thermal shock resistance of ceramic coatings on steels prepared by plasma electrolytic oxidation

Ceramic coatings were successfully prepared on steel by plasma electrolytic oxidation (PEO) in aluminate electrolyte and silicate electrolyte, respectively. The microstructure of the coatings including surface morphology, phase and element composition were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The bonding strength between the ceramic coating and the substrate was tested using different methods including tensile tests and shearing tests. The thermal shock resistance of the coatings was also evaluated. The results indicated that coatings obtained in both electrolytes were porous and coarse. The average diameters of the pores were below 10 μm. PEO coatings obtained in aluminate electrolyte were composed of Fe₃O₄ and FeAl₂O₄, while those obtained in silicate electrolyte were in a noncrystal state. PEO coatings obtained in aluminate electrolyte showed similar change trend of tensile strength and shearing strength with increasing treating time, namely, a relatively high values with middle time treating and low value with short and long time treating. The best coating was the samples treated with 30 min, whose tensile strength was 20.6 MPa and shearing strength was 16 MPa. The tensile strength and shearing strength of coatings obtained in silicate electrolyte were not strongly influenced by the treating time, the values of which were range in 14 ± 2 MPa and 11 ± 2 MPa, respectively. Coatings obtained in both electrolytes showed the best thermal shock resistance with middle time treating. Coatings obtained in silicate electrolyte show a little better thermal shock resistance than those obtained in aluminate electrolyte.     

Exact solutions to a coupled modified KdV equations with non-uniformity terms

The bilinear form of a coupled modified KdV equations with non-uniformity terms is given and a few soliton solutions are obtained. Furthermore, the multisoliton of the coupled system is expressed by Pfaffian.     

化学沉淀法制备硒化铅薄膜

采用化学沉淀的方法沉淀PbSe薄膜,分别加入缓冲剂联氨(方法A)和碘化钾(方法B)。对反应原理进行了分析,对制备过程进行了优化,分别制备出了高质量的PbSe薄膜。采用XRD、SEM、EDS以及红外光谱测试对所制备样品进行了分析。结果表明,两种方法制备均为PbSe多晶薄膜,方法A制备薄膜结晶质量更好,择优生长方向明显;薄膜颗粒度、表面粗糙度都小于方法B;两种薄膜的Pb元素与Se元素比例接近化学计量比,方法B含有少量I元素;两种方法制备样品的吸收边相对带边跃迁都发生蓝移。     

Coupling-induced excitation of a forbidden surface plasmon mode of a gold nanorod

Using the finite-difference time-domain (FDTD) method, we simulate the coupling between a gold nanorod and gold nanoparticles with different plasmonic resonant frequencies/volumes as well as that between the nanorod and a dielectric nanosphere. The influences of coupling with different nanoparticles on the excitation of a forbidden longitudinal surface plasmon mode of the nanorod under normal incidence are investigated. It is found that the cause of this excitation is the broken symmetry of the local electric field experienced by the nanorod resulting from the charge pileup on the other nanoparticle. This result is valuable for understanding the near-field optical characterization of plasmonic metal nanoparticles. Supported by the National Natural Science Foundation of China (Grant Nos. 10821062 and 10804004), the National Basic Research Program of China (Grant No. 2007CB307001), and the Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 200800011023) Contributed by GONG QiHuang     

6.17-W continuous wave operation of a 2132-nm c-cut Tm,Ho:YAP pumped by a laser diode of 794.3 nm

Continuous wave (CW) operation of a c-cut Tm (5 at %), Ho (0.3 at %):YAP laser at 2132 nm wavelength were reported in this paper. In the temperature of 77 K, the Tm,Ho:YAP crystal was double end-pumped by a 21.4 W fiber-coupled laser diode (LD) at the center wavelength of 794.3 nm. Different resonator lengths and output couplers for the total pump power were tried. The resonator length was 205 mm, and the maximum CW output power of 6.17 W was acquired, corresponding to an optical-optical conversion efficiency of 28.8% and a slope efficiency of 35.6%.     

Adaptive Synchronization of Fractional-Order Complex-Valued Uncertainty Dynamical Network with Coupling Delay

Compared with real-valued complex networks, complex-valued dynamic networks have a wider application space. In addition, considering the existence of time delay and uncertainty in the actual system, the synchronization problem of fractional-order complex-valued dynamic networks with uncertain parameter and coupled delay is studied in this paper. In particular, the uncertain parameter is correlated with time delay. By using fractional derivative inequalities and linear delay fractional order equations, the synchronization of uncertainty complex networks with coupling delay is realized. Sufficient conditions for global asymptotic synchronization are obtained. The obtained synchronization results are applicable to most complex network systems with or without delay. Finally, numerical simulations verify the effectiveness of the obtained results.

     

基于非平衡光纤干涉仪的窄线宽激光光源跳模实时测试方法

窄线宽激光器随机发生的跳模现象,是影响光学系统稳定的重要因素.激光器线宽窄往往意味着较长的谐振腔和较小的模间隔,从而给跳模的监测带来了难度.本文提出一种基于非平衡光纤干涉仪的窄线宽光源跳模测试方法,该方法将激光器跳模的频率变化转变为干涉仪的相位变化,并通过相位产生载波(PGC)调制解调技术来检测相位信息,从而实现对跳模过程的监测.该方法灵敏度高,能够长时间连续监控,测试效果优于Fabry-Pérot干涉仪,还可在kHz量级上测量窄线宽激光器的线宽,为单纵模窄线宽激光器研究提供有效的测试手段.