Zn1-xMgxO和Zn1-xMnxO薄膜的制备及其发光性能

采用溶胶-凝胶技术,在Si(110)衬底上制备了Mg、Mn掺杂外延生长的Zn_1-xMg_xO和Zn_1-xMn_xO薄膜,通过XRD、AFM、PL等考察不同杂质浓度对薄膜结晶质量和发光性能的影响。结果表明:Zn_1-xMg_xO和Zn_1-xMn_xO薄膜均具有较高的T_c(002)结构系数和较为光滑、平整的表面形貌。掺杂使得薄膜的紫外发光峰向短波方向移动至365 nm左右,同时Zn_1-xMn_xO薄膜的室温可见光发射得以有效地钝化,使其近带边紫外光发射与深能级可见光发射比例高达56,极大地提高了薄膜紫外发光性能。并对掺杂薄膜紫外发光蓝移和Zn_1-xMn_xO薄膜室温可见光发射的猝灭机理进行了深入探讨,得出掺杂组分为Zn_0.85Mg_0.15O、Zn_0.97Mn_0.03O时,薄膜具有最强的紫外光发射性能。     

GaN薄膜的溶胶-凝胶法制备及其表征

采用溶胶凝胶法成功地制备出氮化镓薄膜.以单质镓为镓源制备镓盐溶液、柠檬酸为络合剂制备出前驱体溶胶,再甩胶于Si(111) 衬底上,在氨气氛下热处理制备出GaN薄膜.X射线衍射（XRD）分析及选区衍射分析（SAED）表明所制备的薄膜是六角纤锌矿结构GaN薄膜;XPS分析其表面,结果显示样品中的镓元素、氮元素均以化合态存在,且Ga：N约为1：1;PL谱分析结果表明所制备的薄膜具有优良的发光性能.     

Electronic structure and optical properties of Nb-doped Sr2TiO4 by density function theory calculation

This paper investigates the effect of Nb doping on the electronic structure and optical properties of Sr2TiO4 by the first-principles calculation of plane wave ultra-soft pseudo-potential based on density functional theory(DFT).The calculated results reveal that due to the electron doping,the Fermi level shifts into conduction bands(CBs) for Sr2 Nb x Ti1 x O4 with x=0.125 and the system shows n-type degenerate semiconductor features.Sr2TiO4 exhibits optical anisotropy in its main crystal axes,and the c-axis shows the most suitable crystal growth direction for obtaining a wide transparent region.The optical transmittance is higher than 90% in the visible range for Sr2 Nb 0.125Ti0.875O4.     

RF SET 超灵敏静电计

单电子晶体管(SET)作为灵敏静电计的灵敏度受到噪声的限制，其中散粒噪声(shot noise)是本征噪声，决定着单电子晶体管灵敏度的极限．利用射频(radio frequency，RF)单电子晶体管的极高的工作频率，可以消除SET的1／f噪声，从而达到极限灵敏度．利用一级低温低噪声放大器和一级室温放大器放大工作在反射模式的射频单电子晶体管的输出信号，使用LC共振电路，抬高了SET右边的整个微波系统的阻抗，使之与单电子的输出阻抗匹配，从而提高了RFSET静电计的灵敏度．     

气相色谱-三重四极杆质谱法测定植物源性食品中棉隆及其代谢物异硫氰酸甲酯残留北大核心CSCD

基于气相色谱-三重四极杆质谱建立了同时快速测定植物源性食品中棉隆及其代谢物异硫氰酸甲酯残留量的方法。对样品前处理及色谱条件进行了优化,蔬菜、水果、谷物、坚果、茶叶和香辛料样品经乙酸乙酯提取,离心后上清液经乙二胺-N-丙基硅烷化硅胶、石墨化炭黑、十八烷基键合硅胶和无水硫酸镁分散固相萃取净化,经DB-17MS色谱柱(30 m×0.25 mm×0.25μm)分离,采用EI源,在多反应监测(MRM)模式下检测,基质匹配外标法定量。在优化实验条件下,目标化合物在0.005~1 mg/L范围内的线性关系良好,相关系数均大于0.99,方法定量限为0.01 mg/kg。空白样品在4个添加水平下的平均回收率为74.2%~117.2%,相对标准偏差(n=6)为2.8%~9.0%,方法的准确度和精密度符合农药残留测定要求。应用建立的方法对实验室日常样品大白菜、韭菜、豇豆、油麦菜、茄子、姜、芹菜、马铃薯、橙、猕猴桃、西红柿、辣椒、大米、茶叶、杏仁和孜然各6个进行检测,均未检出目标物。该方法具有操作简单、快速、灵敏、准确的特点,解决了已有方法中需采用两种前处理方法、两套设备进行检测的不足,能满足植物源食品中棉隆及其代谢物异硫氰酸甲酯的检测要求。     

基于动态网络模型的研发团队隐性知识转移研究

隐性知识在研发团队成员中迅速和有效的共享，对于企业开发新产品和获取竞争优势有重要意义。本文构建了研发团队隐性知识转移的动态网络模型，探讨了团队成员构成的群体网络的结构特征，对研发团队整体知识水平和知识转移速度产生的影响。并利用系统仿真，对模型的主要参数进行分析。模型为企业有效促进研发团队的隐性知识转移提供了建议。     

Error analysis and optimal design of polarization calibration unit for solar telescope

Polarization calibration unit(PCU) has become an indispensable element for solar telescopes to remove the instrumental polarization; the polarimetric accuracy of calibration depends strongly on the properties of PCU. In the paper, we analyze the measurement errors induced by PCU based on polarized light theory and find that the imperfections of the waveplate generate the main calibration errors. An optimized calibration method is proposed to avoid the effects from waveplate imperfections, and a numerical simulation is given to evaluate the polarization accuracy by analyzing the relation between calibration error and intensity instability. The work is very important for solar telescopes with high polarization precision up to 10~(-4) I_c.     

Fermi Level Unpinning and Schottky Barrier Modification by Ti, Sc and V Incorporation at NiSi2/Si Interface

A new method is proposed to modify the Schottky barrier height （SBH） for nickel silicide/Si contact. Chemical and electrical properties for NiSi2/Si interface with titanium, scandium and vanadium incorporation are investigated by first-principles calculations. The metal/semiconductor interface states within the gap region are greatly decreased, which is related to the diminutions of junction leakage when Ti-cap is experimentally used in nickel silicide/Si contact process. It leads to an unpinning metal/semiconductor interface. The SBH obeys the Schottky-Mort theory. Compared to Ti substitution, the SBH for electrons is reduced for scandium and increases for vanadium.     

Ge衬底上GaInP2 材料的生长研究

采用自制的低压金属有机化学汽相淀积LP-MOCVD设备, 在(100)面偏(110)面 9°的Ge单晶衬底上外延生长了GaInP2材料,研究了生长温度 、Ⅴ/Ⅲ比、生长速率等生长参数对GaInP2材料的表面形貌和固相组分的影响.结果表明,当GaInP2材料的生长温度为650～680℃,生长速率为25～35 nm/min,Ⅴ/Ⅲ为180～220时,获得了满足级联电池的GaInP2材料.     

Effect of polyacrylamide on morphology and electromagnetic properties of chrysanthemum-like ZnO particles

Through hydrothermal process, the chrysanthemum-like ZnO particles are prepared with zinc acetate dihydrate (Zn(CH₃COO)₂\cdot 2H₂O) and sodium hydroxide (NaOH) used as main resources under the different concentrations of surfactant polyacrylamide (PAM). The microstructure, morphology and the electromagnetic properties of the as-prepared products are characterized by high-resolution transmission electron microscopy (HRTEM), field emission environment scanning electron microscope (FEESEM) and microwave vector network analyzer, respectively. The experimental results indicate that the as-prepared products are ZnO single crystalline with hexagona wurtzite structure, that the values of slenderness ratio L_d are different in different PAM concentrations, and that the good magnetic loss property is found in the ZnO products, and the average magnetic loss tangent tanδ_u increases with PAM concentration increasing, while the dielectric loss tangent tanδ _e decreases.