蓝宝石衬底上水平生长ZnO纳米线及紫外敏感性能研究

在无催化剂条件下,采用化学气相沉积(CVD)方法在蓝宝石(110)衬底上制备了ZnO纳米线.X射线衍射(XRD)图谱上只有ZnO的(100)衍射峰和(110)衍射峰.扫描电子显微镜分析表明,ZnO纳米线在蓝宝石衬底上水平生长.在样品上蒸镀了金叉指电极,以256nm的紫外光作为光源,测试了样品的紫外光敏感性能,研究表明水平生长的ZnO纳米线对紫外光具有较快的响应,在5V偏压下,光电流与暗电流比为30;当波长为354nm时光响应度达到最大值为0.56A/W.     

Si(100)衬底对ZnO纳米线阵列生长方向的控制作用

采用热分解ZnO粉末法,以Au为催化剂,在Si(100)衬底上外延生长了ZnO纳米线阵列。用扫描电子显微镜(SEM)分析表明:ZnO纳米线的直径在100nm左右,长度约3μm,与衬底表面的夹角约为70.5°,纳米线具有四个特定的倾斜方向A,B,C,D。X射线衍射(XRD)图谱上只有ZnO(0002)衍射峰,说明ZnO纳米线沿C轴择优生长。结合Si与ZnO的晶格结构特征,理论研究得出ZnO纳米线与Si基片的晶格匹配关系为:[0001]_(ZnO)∥[114]_(Si),[0001]_(ZnO)∥[■■4]_(Si),[0001]_(ZnO)∥[1■4]_(Si),[0001]_(ZnO)∥[■14]_(Si),失配度为1.54%。得出了Si(100)衬底对ZnO纳米线生长方向具有控制作用的结论。     

催化剂辅助化学气相沉积法制备准单晶ZnO纳米线

利用Au催化辅助化学气相沉积生长技术,在n-Si(111)衬底上制备了准单晶的ZnO纳米线.X射线衍射分析的结果表明, ZnO纳米线具有明显的沿(0001)方向定向生长的特征.扫描电子显微镜分析表明,ZnO纳米线的典型直径约为100 nm,长度为2～5 μm.讨论了Au催化辅助化学气相沉积生长技术制备ZnO纳米线的原理.     

不同衬底温度下射频磁控溅射磷掺杂ZnO薄膜的性质

为研究在低温衬底上沉积磷掺杂ZnO薄膜的性质,从室温到350℃的范围内磷掺杂的ZnO被磁控溅射到蓝宝石衬底上.样品的XRD谱显示薄膜为＜001＞方向择优生长,ZnO(002)面的衍射峰在250℃时最低.原子力图像分析显示:薄膜的表面形貌随沉积温度而变化,粗糙度随温度升高而增加.样品的XPS谱在134eV附近清晰地观测到...     

在不同衬底上生长ZnO薄膜及其特性研究

在不同衬底温度下用脉冲激光沉积法(PLD)分别在n-Si(111)、蓝宝石(001)和非晶石英衬底上生长了ZnO薄膜。首先对薄膜进行了X射线衍射(XRD)分析,找出在三种不同衬底上制得的结晶质量最好的ZnO薄膜所对应的最佳衬底温度。然后对最佳衬底温度下得到的ZnO薄膜分别进行了X射线衍射(XRD)、光致发光谱(PL)和原子力显微镜(AFM)分析。结果表明,在硅衬底上生长的ZnO薄膜XRD谱半高宽最小,PL谱特征发光峰强度最强,AFM下的平均粒径最大,说明硅衬底上生长的ZnO薄膜结晶质量最好,而在石英衬底上生长的ZnO薄膜结晶质量最差。     

不同衬底上氧化锌薄膜的金属有机化学气相沉积方法生长

氧化锌薄膜通过金属有机化学气相沉积方法生长在康宁玻璃与α-蓝宝石衬底上,研究了有关薄膜的生长质量与发光特性.通过X光衍射方法测试研究发现,不仅在以α-蓝宝石为衬底的样品中,同时,在以玻璃为衬底的样品中都发现了氧化锌(0 0 2)方向生长的尖峰,表明生长在两种衬底上的样品都是高度的C向生长.对两种样品的荧光谱研究发现,两者的紫外峰位于374 nm附近,在以α-蓝宝石为衬底的样品中,有深能级发射,但在以玻璃为衬底的样品中没有发现,表明在玻璃衬底上我们生长出了高质量的氧化锌薄膜.通过原子力显微镜,对生长在两种衬底上薄膜的表面形貌做了观察,其晶粒的大小与表面粗糙度有一定的差别,表明二者都是以柱状形式生长的.     

ZnO纳米岛的MOCVD自组装生长

利用低压金属有机源气相沉积(LP-MOCVD)技术,在 (0001)蓝宝石衬底上生长ZnO纳米岛,发现在适当的生长条件下,可以生长出规则排列的纳米岛.实验发现随着生长时间的增加,在蓝宝石衬底上沉积的ZnO晶体颗粒无论是密度还是体积都在增加,并出现颗粒之间的交叠现象.与厚膜材料相比,相应的室温PL谱上显示出带边蓝移现象,随着生长温度的提高将大大增加ZnO在蓝宝石衬底上成核的困难.另外,所有样品的室温PL谱在带边附近均存在一个展宽峰,这可能是由表面态或晶体缺陷造成的.研究表明选择合适的生长时间与生长温度是利用MOCVD生长高质量ZnO纳米岛的关键因素之一.     

不同晶种上ZnO纳米线的生长及紫外光电导特性

采用射频磁控溅射法在石英衬底上沉积了AZO和ITO透明导电膜,然后采用溶液化学法以两种导电膜为晶种分别生长ZnO纳米线。利用扫描电镜和X射线衍射等测试手段对样品进行表征,进而通过一种垂直测试结构,研究其紫外光电导特性的差异。结果表明:晶种对纳米线的生长起决定性作用,只有在结晶良好并且择优取向的AZO膜上才能生长出垂直于衬底且取向一致的ZnO纳米阵列,而在ITO膜上,ZnO纳米线的取向具有很大的随机性。AZO上垂直生长的纳米线紫外响应速度较快,且呈现良好的欧姆接触特性,但两种样品恢复时间都较长,分析认为是纳米线曝光面积不同和内部的缺陷、表面态等原因造成的。     

自催化方式制备ZnO纳米线及光致发光特性

采用化学气相沉积法,不用催化剂,在Si(111)基片上制备了ZnO纳米线。扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在100nm左右。X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰。室温下光致发光谱(PL)中出现了389nm和357nm的紫外峰以及五个蓝光峰(450,468,474,481和491nm)。389nm峰为自由激子复合发射357nm峰是在LO声子的参与下,自由载流子碰撞形成自由激子过程的发光行为;468nm峰系电子从氧空位形成的浅施主能级向价带跃迁发光;450nm峰系电子从导带向锌空位形成的浅受主能级跃迁发光;474,481和491nm峰是声子伴线。     

热氧化法制备ZnO薄膜及其紫外探测特性研究

采用电子束蒸发方法在玻璃衬底上沉积了Zn薄膜,然后在空气中进行了400 ℃至550 ℃加热退火处理,并基于金属-半导体-金属(MSM)平面式结构,制备了ZnO光电导型紫外探测器.实验发现:退火后的薄膜样品表面出现了ZnO纳米线,纵横比在300～1000间;探测器的响应峰值波长约为360 nm,紫外区光响应度是可见区的5倍以上;360 nm紫外光照射的瞬态响应符合e指数变化规律,e指数曲线拟合所得到的驰豫时间常数反映了这个过程中的时间积累.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.