ZnO纳米棒与Si(111)和Si(100)衬底的外延关系(英文)

运用热蒸发技术在Si(111)和Si(100)基片上制备了ZnO纳米棒。SEM表征显示,ZnO纳米棒的直径约100nm,长度均匀,大约3μm;XRD表征发现ZnO纳米棒沿[0001]晶向择优生长。通过实验结果与理论分析得出:对于Si(111)基片上的样品,大部分ZnO纳米棒沿6个对称方向生长,而且与基片之间的夹角为54.7°,ZnO与Si(111)的外延关系为[0001]ZnO‖[114]Si,[0001]ZnO‖[4]Si,[0001]ZnO‖[141]Si,[0001]ZnO‖[4]Si,[0001]ZnO‖[411]Si,或[0001]ZnO‖[4]Si。对于Si(100)基片上的样品,大部分ZnO纳米棒沿4个对称方向生长,与基片之间的夹角为70.5°,其外延关系为[0001]ZnO‖[114]Si,[0001]ZnO‖[4]Si,[0001]ZnO‖[14]Si,或[0001]ZnO‖[14]Si。通过比较分析得出Si基片可以控制ZnO纳米棒的生长方向。     

响应波段外激光辐照PC HgCdTe 探测器系统实验研究

文中对多元多光谱红外探测器系统响应波段外激光的辐照效应进行了深入的实验研究并对实验结果进行了分析。以1．06μm激光辐照三元光导型碲镉汞探测器系统的实验为例，说明了系统响应波段外激光辐照效应的实验规律。实验结果发现：探测器对系统响应波段以外的激光仍有响应信号，但响应规律与对波段内激光的响应不同，出现新的现象。研究表明：Ge窗口被激光加热是导致探测器输出信号的根本原因，信号输出曲线由探测器的电阻—温度特性决定。     

Hydrothermal Growth: Polymer‐Templated Hydrothermal Growth of Vertically Aligned Single‐Crystal ZnO Nanorods and Morphological Transformations Using Structural Polarity (Adv. Funct. Mater. 18/2010)

Position‐configurable, vertical, single‐crystalline ZnO nanorod arrays are fabricated via a polymer‐templated hydrothermal growth method at a low temperature of 93 °C. A sol‐gel processed dense c‐oriented ZnO seed layer film is employed to grow nanorods along the c‐axis direction [0001] regardless of any substrate crystal mismatches. Here, one‐beam laser‐interference lithography is utilized to fabricate nanoscale holes over an entire 2‐in. wafer during the preparation of the polymer template. As such, vertically aligned ZnO nanorods can be grown from the seed layer exposed at the bottom of each hole. Furthermore, morphological transformations of the ZnO nanorods into pencil‐like, needle‐like, tubular, tree‐like, and spherical shapes are obtained by controlling the growth conditions and utilizing the structural polarity of the ZnO nanorods.     

Fe2+-Induced In Situ Intercalation and Cation Exsolution of Co80Fe20(OH)(OCH3) with Rich Vacancies for Boosting Oxygen Evolution Reaction

The efficiency of water splitting is largely hindered by the sluggish kinetics of the oxygen evolution reaction. Cobalt-based (oxy)hydroxides are promising electrocatalysts, but their performance is still under the expected goal due to the restricted active sites and intrinsic activity. Herein, Co₈₀Fe₂₀(OH)(OCH₃) (CoFeMe) is synthesized with intercalation and rich vacancies by a cation exsolution process in a one-step solve-thermal reaction. With the help of the Fe incorporation, the specific surface area of CoFeMe increases to 101.6 m² g⁻¹, which is six times that of Co(OH)(OCH₃) (CoMe) (16.5 m² g⁻¹). Also, the induced rich vacancies are traced in the X-ray absorption spectra of CoFeMe. Because of the synergistic effect between the intercalation, Fe incorporation and vacancies, the overpotential of CoFeMe is only 240 mV to drive the current density to 10 mA cm⁻², which is reduced 110 mV compared with that of pristine CoMe (350 mV).     

Wet chemistry synthesis of ZnO crystals with hexamethylenetetramine(HMTA): Understanding the role of HMTA in the formation of ZnO crystals

ZnO crystals have been prepared via a simple aqueous solution route using zinc acetate-hexamethylenetetramine (HMTA) solution. To understand the role of HMTA in the formation processes of ZnO crystals, concentration measurements of Zn(II) remaining in the solution as well as SEM and XRD analyzes of the solid product have been made at regular intervals. The results demonstrated that the HMTA concentration has determinative effects on the growth rate of obtained ZnO products by controlling the composition of zinc complex species and mediating the transformation rate of building blocks. XRD results revealed the single phase nature with the wurtzite structure of the as prepared ZnO rods. X-ray photoelectron spectroscopy confirmed high purity of the ZnO rods. By varying the concentration of HMTA in the solution, the average size of rods was varied from 5 μm to 10 μm. Photoluminescence spectra indicated that the photoluminescent intensity of the emission peak at 380 nm increase to different degree with increasing HMTA concentration. These results revealed that the concentration of HMTA plays a vital role to control the properties of ZnO crystals.     

sol-gel法制备(002)高度定向的Li:ZnO薄膜

用sol-gel法在玻璃载玻片上旋涂3~9层制备氧化锌薄膜。用X射线衍射、扫描电镜等研究了掺Li、旋涂层数、溶胶的浓度以及热处理温度对氧化锌薄膜(002)定向性的影响。结果表明,溶胶中掺入一定量的Li可显著地促进ZnO沿(002)生长;浓度为0.45mol/L旋涂3层或浓度为0.25mol/L旋涂7层的样品,即使有Li的掺入也不能呈现较好的(002)定向性,这是由于薄膜太薄所致;提高热处理温度至610℃,有利于薄膜(002)高度定向。     

稀土元素(Sm,Tm)掺杂ZnO的电学与光学性质

运用Materials Studio软件中的CASTEP子模块,借助第一性原理平面波超软赝势法,计算分析了稀土元素(Sm,Tm)掺杂ZnO前后的能带结构、态密度以及光学性质变化情况。计算结果表明,掺杂后体系的能带部分更加稠密,出现新的杂质能级,费米能级从价带顶处上移进入导带部分,出现载流子简并现象,形成简并半导体。掺杂体系显示出更强的金属性,呈现n型导电。同时定性分析了体系前后的光学吸收系数与介电函数的变化情况。     

平顶陡边响应的谐振腔增强型(RCE)光电探测器的分析

报道了一种具有平顶陡边响应的谐振腔增强型(RCE)光电探测器.使用数值模拟的方法对这种新型谐振腔增强型(RCE)光电探测器与传统的RCE光电探测器的响应曲线和串扰特性进行了分析和对比, 分析了在半导体材料生长时厚度偏差对平顶陡边响应的RCE光电探测器响应曲线的影响,还分析了入射光的入射角和偏振态对平顶陡边响应的RCE光电探测器响应曲线的影响.     

在硅片上电沉积不同形貌的ZnO纳米结构的研究

采用简单的电化学沉积方法,通过调节电解液浓度和pH值,在硅衬底上实现了ZnO纳米结构的形貌控制。通过X射线衍射、扫描电镜和光致发光谱等表征手段对不同形貌的ZnO纳米结构进行了研究。研究发现,通过调节沉积条件,可以获得纳米棒、纳米簇丛和纳米片等不同形貌的ZnO纳米结构。其中,溶液pH值是纳米ZnO从一维结构到二维结构转变的关键因素。当pH值为12时,所获得的纳米ZnO为二维片状结构。光致发光谱显示二维ZnO纳米片的紫外本征峰相对于一维ZnO纳米棒发生了明显的蓝移,并且可见区的发光峰大大降低。这一结构将在光电器件、传感器等领域有很好的应用前景。     

Growth of GaN Films on Si (100) Buffered with ZnO by Ion-Beam-Assisted Filtered Cathodic Vacuum Arc Technique

GaN films have been fabricated on Si (100) substrates with ZnO buffer layers by an ion-beam-assisted filtered cathodic vacuum arc (I-FCVA) technique at␣450°C. GaN films are highly (002)-oriented with a hexagonal structure examined by X-ray diffraction. The room-temperature photoluminescence spectrum of the GaN film exhibits a strong and sharp band-edge emission peak at 3.36 eV. The obtained results demonstrate the potential of the I-FCVA technique for the fabrication of high-quality GaN layers on Si substrates.     

Step Response of Lossless Nonuniform Transmission Lines with Power-Law Characteristic Impedance Function (Short Paper)

The step-response waveform of the Iossless nonuniform transmission line possessing a characteristic impedance function Z/sub c/(x)= Z/sub 0/(1 + eta x)/sup 2n/, n = 0,1,2,..., is deduced. The simple and closed-form solutions should be useful for pulse transient analysis involving nonuniform transmission lines.     

低能量He-Ne激光血管内照射结合氧疗治疗脑梗塞的疗效观察

临床观察表明低能量He－Ne激光血管内照射结合氧疗治疗脑梗塞，疗效较单用低能量He－Ne激光血管内照射血液效果更佳，是一种治疗脑梗塞简便有效的方法，病人乐于接受，值得深入研究。     

阵列误差影响下的RBF神经网络波达方向估计

针对阵列误差(阵元间互耦、通道失配)影响下波达方向估计问题,提出一种新型的基于径向基神经网络侦察测向系统。这种系统采用直接数据域补偿算法对输入数据进行误差补偿,从而获得正确的基函数中心。在无需对RBF神经网络测向系统作任何改进的情况下,可获得对波达方向的准确估计。为了减少输入,利用信号协方差矩阵的对称性以及对角线元素不包含信号方向信息的特点,仅考虑协方差矩阵中的上三角部分元素作为网络输入。给出了应用该方法的具体步骤。仿真实验表明,基于这种RBF网络的侦察测向系统达到了很高的精度。     

f_(max)为30.8GHz的超薄Al_2O_3绝缘栅GaN MOS-HEMT器件(英文)

报道了一种利用原子层淀积(ALD)生长超薄(3.5nm)Al2O3为栅介质的高性能AlGaN/GaN金属氧化物半导体高电子迁移率晶体管(MOS-HEMT).新型AlGaN/GaNMOS-HEMT器件栅长1μm,栅宽120μm,栅压为 3.0V时最大饱和输出电流达到720mA/mm,最大跨导达到130mS/mm,开启电压保持在-5.0V,特征频率和最高振荡频率分别为10.1和30.8GHz.     

添加BaCu(B2O5)和ZnO的CaO-Li2O-Sm2O3-TiO2陶瓷低温烧结研究

采用固相反应法制备了添加复合助烧剂BaCu(B<,2>O<,5>)-ZnO的16CaO-9Li<,2>O-12Sm<,2>O<,3>-63TiO<,2>(CLST)陶瓷研究了所制CLST陶瓷的烧结特性、微观结构及介电性能.结果表明:低熔点的BaCu(B<,2>O<,5>)-ZnO复合助烧剂的加入,使CLST陶瓷的烧结温...     

背景电离层对低频重轨星载InSAR影响分析

由于大口径天线远场条件苛刻、杂波多径影响大,使得大型地基雷达的极化校准成为雷达工程技术领域的难点问题,频域动态极化校准算法是一种很好的解决方案,但存在极化有源校准器收/发天线隔离度低、天线方向图不对称等问题,导致极化校准的精度降低。针对上述问题,提出了一种基于非匀速旋转单天线PARC(Polarimetric Active Radar Calibrator)的极化校准方法,能够克服传统频域动态校准算法的缺点,有效提高雷达极化校准的精度。