Fabrication and performance of MMW and SMMW platelet horn arrays

Future spaceborne millimeter and sub-millimeter wave sensing systems will require the sensitivity and resolution only achievable with large focal plane array receiving systems. A technique has been developed for the low cost fabrication of large arrays of millimeter and sub-millimeter wave corrugated feed horns. These arrayed horns exhibit high efficiency and symmetrical receiving patterns and are compatible with integrated receivers. W-band test results of a 3×3 array are presented.     

Fabrication and performance of color filter arrays for solid-state imagers

A technique has been developed for the fabrication of a color filter array (CFA) to be used in conjunction with a solid-state area sensor to provide three-color image information from a single sensor. The fabrication technique employs sublimable dyes which are heat-transferred through photoresist windows onto a polymer receiving layer. Good edge sharpness and a low dye penetration depth into the polymer have been achieved. The predicted and measured spectral response of the color channels of the composite device are in good agreement. The pattern noise associated with CFA transmittance fluctuations from element to element is on the order of 10 percent.     

Fabrication and electrical performance of high-density arrays of nanometric silicon tips

We propose and demonstrate a simple and low cost process for the fabrication of large area arrays of nanometric silicon tips, for use as Field Emission Devices (FEDs). The process combines Interference Lithography (IL) with isotropic Reactive Ion Etching (RIE). Si tips with typical curvature radius of 20 nm and height of 900 nm were recorded with a periodicity of 1 μm (density of 10⁶ tips/mm²) covering a Silicon wafer of 2 in. The measurement of the electrical performance of the arrays demonstrates the feasibility of the association of these two techniques for recording Field Emission Tips.     

High-speed real-time visible light communication system based on InGaN/GaN-base multi-quantum well blue micro-LED

Visible light communication (VLC) technology is a new type of wireless communication technology, which employs a light source as the carrier of information to realize illumination and communication simultaneously. This paper adopts a single InGaN/GaN-base multi-quantum well blue micro-light emitting diode (LED) as the light source, designs pre-emphasis circuit, LED driver circuit, impedance matching network, etc., and builds a high-speed real-time VLC system. It has been verified that the LED achieves a 3 dB modulation bandwidth of 450 MHz or more; and the real-time communication rate reaches over 800 Mbit/s at a distance of 2 m. The communication bit error rate (BER) is as low as at a communication rate of 622 Mbit/s. Experimental indicators including 3 dB bandwidth, communication rate, and communication BER are all taken into account. Therefore, this VLC system supports high-quality high-speed real-time communication.     

背照式InGaN紫外探测器的制备与数值模拟

研究了背照式InGaN p-i-n结构的紫外探测器的制备与数值模拟.通过低压金属有机化学气相沉积(MOCVD)方法生长p-GaN/i-InGaN/n-GaN外延片,采用标准的Ⅲ-Ⅴ族器件制备工艺,成功制备出p-i-n结构的InGaN紫外探测器.探测器台面半径为30 μm,在-5V偏压下暗电流为-6.47×10 1 2 A,对应的电流密度为2.29×10-7 A/cm2.该探测器响应波段为360～380 nm,在371 nm处达到峰值响应率为0.21 A/W,对应的外量子效率为70％,内量子效率为78.4％.零偏压下,优值因子R0A=5.66×107 Ω·cm2,对应的探测率D* =2.34×1013 cm·Hz1/2·W-1.同时,利用Silvaco TCAD软件进行数值模拟,响应率曲线仿真值与实验值拟合较好.     

InGaN/GaN多量子阱太阳电池的研制及特性研究

利用金属有机物化学气相沉积技术在蓝宝石衬底上生长了InGaN/GaN多量子阱外延结构,高分辨率X射线衍射测量结果显示,量子阱结构界面清晰,周期重复性很好,InGaN阱层的In组分约为0.2。利用该外延结构制备的InGaN/GaN多量子阱太阳电池的开路电压为2.16V,转换效率达到了0.64%。器件的I-V测量结果显示,在光照条件下,曲线的正向区域存在一明显的"拐点"。随着聚光度的减小,I-V曲线的"拐点"逐渐向高电压区域移动,同时器件的开路电压也随之急剧下降。通过与理论计算对比,发现器件开路电压的下降幅度明显大于理论计算值。进一步分析表明,InGaN量子阱的极化效应不仅是I-V曲线产生拐点以及器件开路电压下降过快的主要原因,也是影响氮化物太阳电池性能的关键因素之一。     

InGaN紫外探测器的制备与性能研究

介绍了InGaN紫外探测器的研制过程,并给出了器件的性能。利用金属有机化学气相沉积(MOCVD)方法生长GaN外延材料,通过刻蚀、钝化、欧姆接触电极等工艺,制作了正照射单元In0.09Ga0.91N紫外探测芯片。并对该芯片进行了I-V特性、响应光谱等测试,得到芯片的暗电流Id为1.00×10-12 A,零偏压电阻R0为1.20×109Ω。该紫外探测器在360~390nm范围内有较高的响应度,峰值响应率在378nm波长处达到0.15A/W,在考虑表面反射时,内量子效率达到60%;优质因子R0A为3.4×106Ω·cm2,对应的探测率D*=2.18×1012 cm·Hz1/2·W-1。     

Fe纳米线的制备及其磁性能研究

采用电化学沉积法封装阳极氧化铝(AAO)模板,制备出不同直径的Fe纳米线阵列。Fe纳米线阵列的形貌、组成、晶型、磁学性能分别通过场发射扫描电子显微镜(SEM)、X-射线能谱仪(EDS)、X-射线衍射仪(XRD)、震动样品磁强计(VSM)进行表征。结果表明:电化学沉积法可以制备出直径为33~95 nm的Fe纳米线;纳米线排列有序,粗细均匀,具有明显的[110]择优取向。VSM测试结果表明纳米线的直径对其磁性能影响很大。当纳米线直径为33~40 nm时,纳米线具有明显的磁各向异性,垂直模板表面的方向为易磁化方向,该方向上矫顽力达112 745.4 A/m以上,矩形比达0.43以上;当纳米纤维直径为75~95 nm时,纳米线的磁各向异性较弱,轴向上矫顽力和矩形比也较小。     

InGaN/GaN多量子阱纳米线发光二极管制备及研究

用SiO2纳米图形层作为模板在以蓝宝石为衬底的n-GaN单晶层上制备了InGaN/GaN多量子阱纳米线,并成功实现了其发光二极管器件(LED).场发射扫描电子显微镜(FESEM)的测量结果表明,InGaN/GaN多量子阱纳米线具有光滑的表面形貌和三角形的剖面结构.室温下阴极射线荧光谱(CL)的测试发现了位于461 nm...     

NOA73材料的曲面微透镜阵列的制作

为了实现生物复眼的光学性能,介绍了一种仿生物复眼结构通过使用光刻胶熔融法和NOA73(norland optical adhesive)紫外曝光固化技术。首先采用光刻胶熔融法将一系列具有不同曲率、宽度的平面微凸透镜制作在Si基底上,且微透镜阵列具有统一的聚焦特性和光滑度;通过比较NOA73、PDMS两种平面微透镜阵列的聚焦效果,得到NOA73材料具有更好的光学性能;然后利用PDMS的柔韧特性和NOA73紫外曝光固化的特性制作出曲面微凸透镜阵列;最后对曲面微透镜阵列进行成像测试、光强分布测试,结果表明,通过上述工艺制作的曲面微凸透镜阵列,最后对曲面微透镜阵列进行成像测试、光强分布测试,可知通知这种工艺制作的曲面微透镜阵列的尺寸达到微米,光学性能优秀,透光率基本达到100%,具有很好的重复性,可行性且制作简单、快速和低成本,并能模仿复眼结构的部分光学特性。     

图形化氧化锌阵列的制备及其场发射性能研究

为了减小场发射的屏蔽效应,采用图形化技术对氧化锌(ZnO)纳米枝阵列进行调控,并研究图形化ZnO枝阵列的性能。首先采用光刻法在ITO导电玻璃上制备图形化ZnO种子层,再用电沉积法在图形化种子层上生长ZnO纳米枝阵列。利用扫描电子显微镜(SEM)、X射线衍射(XRD)研究所制备的图形化ZnO阵列形貌、结构等,并测试其场发射性能。研究结果表明,制备的图形化ZnO纳米枝是圆阵列,直径为330μm左右,纳米ZnO主干平均直径为400~500nm,发现主干上有一些精细的类似锥状的纳米量级微细枝结构,并且具有良好的场发射性能,开启场强为2.15V/μm,场增强因子为16 109。该图形化生长ZnO阵列阴极的方法是一种能较好改善材料场发射性能的方法,在场发射应用领域表现出较好的前景。     

基于激光加工的玻璃透镜阵列制备

为了实现蓝宝石微透镜阵列模板的可控制备,采用刻蚀辅助激光加工技术得到了形貌可控、排列均匀的密排步蓝宝石微凹透镜阵列模板,并结合高温浇铸转写技术实现了K9玻璃微凸透镜阵列的快速制备;基于蓝宝石和玻璃之间较大的热膨胀系数差,实现了蓝宝石和玻璃的有效分离.结果表明,所制备的玻璃透镜阵列具有较高的表面平滑度,表面粗糙度仅有2n...     

Fabrication and some applications of large-area silicon field emission arrays

A method of fabricating large-area arrays of sharply-pointed field emitters at densities up to 1·5 × 10⁵ per cm² from single crystal silicon wafers is described. The point emitters are formed by etch-undercutting a precision oxide pattern which is delineated on the silicon surface by projection photolithography. Observations indicate that emitters with very small tip dimensions in the 200Årange are formed. In the presence of an external electric field, such as produced by a voltage applied to a closely-spaced, planar anode, multiple-emitter arrays are shown to field-emit electrons uniformly over areas up to 3 cm dia. Two important applications currently being explored, are discussed: (1) High resistivity, p-Si has been utilized to develop experimental field emission photocathodes with which field emission imaging has been demonstrated. These photoemitters exhibit very high photo-sensitivities at visible and near i.r. wavelengths. For example, at 0·86 μm, the measured quantum efficiency is 25 per cent which is about five-times higher than the red-sensitive S-20 photocathode and comparable to the highest reported sensitivities of the III–V photosurfaces; (2) N-type emitter arrays show considerable promise as high current, cold cathodes and total emission currents of 1/4 A from 1 cm² areas of 100 Ω-cm n-type emitters have been obtained. Measurements were made under pulse conditions because of anode dissipation considerations.     

砷掺HgCdTe长波红外光电二极管阵列的制备与性能

采用砷(As)掺杂HgCdTe材料研制了响应截止波长为12.5 μm,规格为256×1的长波红外光电二极管阵列.实验设计了一种新的pn结测量方法,测量发现砷掺长波HgCdTe材料离子注入形成pn结深度在3.6～5.3 μm之间,而其最大横向尺寸大约是设计尺寸的1.3倍.实验采用一种改进的表面处理工艺制备了砷掺HgCdTe长波红外光电二极管阵列,获得了良好的电学性能,该工艺与常规表面处理工艺相比可以使器件峰值阻抗提高2个量级,而-0.5v偏压下的动态电阻可提高约30倍.研究认为,器件性能提高的原因是由于改进工艺可以有效抑制器件表面漏电流.     

Characterization and performance evaluation of coupledmultiwaveguide arrays

A new and effective nonintrusive method for characterization of N coupled waveguides is presented. The method is able to furnish readily the coupling parameters of most significance, and furnishes in addition, a way of assessment of overall device quality and performance. The procedure is based on a semi-empirical implementation of coupled mode theory, by means of which different functions are defined for different input configurations. In a well-functioning device, all these function should attain a common single minimum, out of which the coupling coefficient and additional parameters of the device are deduced. Devices were fabricated on Z-cut LiNbO₃ crystals by in-diffusion of titanium. The method was applied in order to measure the wavelength and polarization dependence of the coupling coefficient     

Fabrication of arrays of carbon micro- and nanostructures via electrochemical etching

New methods to pattern and etch a variety of materials are proving to be extremely important owing to the broad impact of microfabrication technology on chemistry and biology. A method, for etching graphitic carbon materials that opens pathways for the creation of arrays of carbon structures, has been developed. The method involves standard photolithographic pattern transfers to a thin carbon film and anodisation of the exposed carbon substrate in basic electrolytes. Structures of various shapes can be fabricated that range in size from tens of microns to submicrons. Arrays of these structures can be fabricated over areas encompassing hundreds of microns with low failure rates. The shape, size and distance between array objects are easily controlled by the fabrication procedure. Scanning electron microscopy is used to visualise the various structures fabricated. The authors show that this technology is useful for the fabrication of microelectrode arrays.     

Fabrication of ECL gate arrays on quick turn-around line

A quick turn-around line (QTL) technology, including a high-speed on-line data system, electron-beam direct writing, and dry process technologies are described in this paper. Electron-beam pattern data is converted by a VAX 11/780 and transmitted to the electron-beam exposure system (EBES) through a communication controller at the speeds of 1 Mbits/s. After various data manipulations, patterns are quickly written directly on wafers. The first metal layer using an Al-Si-Cu alloy is etched in a reactive ion beam etcher with carbon tetrachloride (CCl4). In order to avoid the charge-up phenomenon of the electron beam, the surface of the silicon nitride (SiN) interlevel insulation layer is coated with a thin conductive layer of TiW. TiW/SiN layers are successively etched by the reactive ion etching (RIE) with CF4+ O2(2%). The damage induced by electron-beam irradiation on the device is perfectly annealed out with a 450°C anneal. Bias-temperature tests have been performed on various logic circuits used in a main frame computer.     

Fabrication of periodic square arrays by angle-resolved nanosphere lithography

We investigate the fabrication of periodic square arrays of solid gold islands by angle-resolved nanosphere lithography (ARNSL) in conjunction with thermal evaporation and etching. By varying θ (the tilt angle between the direction of gold deposition beam and the substrate surface normal) and ? (the substrate rotation angle about the beam axis), adjacent islands on a deposited hexagonal gold array will have a constant and periodic difference in height. Upon etching, this height bias will result in the shorter structures being removed to produce an array with a different symmetry from the original hexagonal symmetry of the parent mask. By depositing at three directions of ? = 0°, 120° and −120° with a constant θ = 20°, experimental results show that deposited two-dimensional gold periodic arrays will have a measurable difference in height between adjacent islands. Etching of the resulting patterns produced periodic near-square arrays with triangular nanostructures. Thus the combination of ARNSL and etching can allow selective periodic nanostructures to be removed, increasing the diversity of array symmetries available through nanosphere lithography.     

Fabrication and characterization of Co-Pt nanodot arrays by nanoimprint lithography and electrodeposition

Co-Pt nanodot arrays of 50 nm in diameter and 100 nm pitch were fabricated by nanoimprint lithography and electrodeposition process. A polymer mold used was replicated from a Si master mold with nanopatterns which were fabricated by EBL and ICP-RIE, where hydrophobic surface of these was achieved by FOTS coating. UV-NIL was successfully performed under pressures of 5 MPa for 5 min with an UV exposure time of 30 s, where the substrate was Ru (30 nm)/NiFe (10 nm)/Ta (5 nm)/Si (1 0 0). The size of patterns was measured at 53 nm in diameter, 25 nm in height, 100 nm in pitch. Finally, Co-Pt nanodot arrays were galvanostatically electrodeposited and characterized. The size and the composition of these arrays were measured to be 50 nm in diameter and 100 nm in pitch and Co-23.6 at.% Pt, respectively. According to MFM analysis, these arrays for the remnant states represent a single domain structure of perpendicular direction with a magnetic field, where a field of 15 kOe was applied perpendicular to the sample plane. These results show that for the Co-Pt dot arrays of 50 nm diameter perpendicular magnetic signal can be recorded and switched.     

Realization and performance of as-fabricated SGDBR multiwavelengthlaser arrays

For simplifying the fabrication and operation of multiwavelength laser arrays, sampled grating distributed Bragg reflector (SGDBR) lasers are utilized to form the arrays, where the two SGDBR mirrors of each laser are fabricated on waveguides of different thicknesses. Fabrication of such laser arrays requires a single step of holographic exposure to realize the gratings. The lasers in an array can output wavelength combs of narrow wavelength spacing without the necessity of coarse tuning to the mirrors. We demonstrate monolithically integrated 16-wavelength laser arrays of which the wavelengths are aligned to the International Telecommunication Union grid with single-electrode operation