MOCVD生长GaAs/AlGaAs量子阱研究

利用常压MOCVD技术在较低生长速率下生长出多种GaAs/AlGaAs多量子阱结构材料,利用低温PL谱和TEM对材料结构进行了表征。所得势阱和势垒结构厚度均匀平整,最窄阱宽为1.8nm。本研究表明,低速率(γ≤0.5nm/s)连续生长工艺能够避免杂质在界面富集,优于间断生长工艺,且在掺si n~+-GaAs衬底上所得量子阱发光强度高于掺Cr SI-GaAs衬底上的结果。     

MOCVD生长1.06μm波段InGaAs/GaAs单量子阱材料的发光特性研究

利用金属有机化学气相沉积(MOCVD)技术,在不同偏向角的GaAs衬底上生长了InGaAs/GaAs单量子阱外延结构。通过对样品室温光致发光(PL)谱测试结果的分析,讨论了衬底偏向角、量子阱层生长温度以及V/III比对外延片发光波长、发光强度及PL谱半峰全宽(FWHM)的影响。发现在相同生长条件下,对于InGaAs/GaAs应变量子阱结构,在GaAs(100)偏111A晶向较小偏向角的衬底上生长的样品PL谱发光强度较大,半峰全宽较窄;量子阱层低温生长的样品发光强度更强;增大量子阱层V/III比可以提高样品的发光强度,同时PL谱峰值波长出现红移。     

MOCVD生长1．06μm InGaAs／GaAs量子阱LDs

用低压MOCVD生长应变InGaAs/GaAs量子阱,采用中断生长、应变缓冲层(SBL)、改变生长速度和调节Ⅴ/Ⅲ等方法改善InGaAs/GaAs量子阱的光致发光(PL)质量。PL结果表明,10s生长中断结合适当的SBL生长的量子阱PL谱较好。该量子阱应用于1.06μm激光器的制备,未镀膜的宽条激光器(100μm×1000μm)有低阈值电流密度(110A/cm2)和高的斜率效率(0.256W/A,per.facet)。     

阱内δ掺杂GaSbBi单量子阱红外发光效率的光致发光光谱研究

采用变激发功率红外光致发光(Photoluminescence,PL)光谱方法研究四个不同阱内δ掺杂面密度的GaSb_0.93Bi_0.07/GaSb单量子阱(Single Quantum Well,SQW)及其非掺杂SQW参考样品。通过分析GaSbBi SQW和GaSb势垒/衬底成分的PL强度演化,发现阱内δ掺杂导致红外辐射效率显著降低,相对下降幅度约为33%-75%。进一步分析结果表明,发光效率下降来源于界面恶化引发的“电子损失”和阱内晶格质量下降导致的“光子损失”的共同作用。这一工作有望为稀Bi红外发光器件的性能优化提供帮助。     

垒层Si掺杂对AIGaInP/GaInP多量子阱性能的影响

低压MOCVD方法生长了垒层掺Si与不掺Si的AlGaInP/GaInP多量子阱结构,运用X双晶衍射与光荧光技术研究了掺Si对量子阱性能的影响.测试结果表明垒层掺Si使量子阱的生长速度增加,掺Si量子阱的光荧光强度比未掺Si量子阱的光荧光强度增强了1 3倍.     

掺Te 的GaSb薄膜分子束外延生长及缺陷特性

分析了非掺GaSb材料及在GaAs衬底上用分子束外延生长掺杂Te的GaSb薄膜材料的缺陷特性,主要应用正电子湮没多谱勒展宽谱方法,并结合原子力显微镜和X射线衍射测试进行.多谱勒展宽谱研究表明,采用分子束外延法生长的掺杂Te的n型半导体GaSb薄膜材料的S参数比体材料小,所得缺陷主要是单空位与间隙原子,而几乎无复合体的缺陷类型.     

Si掺杂的AlGaInP/GaInP多量子阱光学特性

低压MOCVD方法生长了掺Si与不掺Si的AlGaInP/GaInP多量子阱结构,运用X射线双晶衍射与光荧光技术研究了掺Si对量子阱性能的影响.测试结果表明掺Si使量子阱的生长速度增加,掺Si量子阱的光荧光强度比未掺Si量子阱的光荧光强度改善了一个数量级.     

AlGaN中Mg掺杂对蓝光发光二极管光电性质的影响

采用金属有机化学气相沉积技术生长了GaN基多量子阱(MQW)蓝光发光二极管外延片,并采用高分辨率X射线衍射仪(HRXRD)和光致光谱仪(PL)表征晶体质量和光学性能,其他的光电性能由制成芯片后测试获得,目的是研究外延片p型AlGaN电子阻挡层Mg掺杂的优化条件.结果表明,在生长p型AlGaN电子阻挡层的Cp2Mg流量为300 cm3/min时,蓝光发光二极管获得最小正向电压VF,而且在此掺杂流量下的多量子阱蓝光发光二极管芯片发光强度明显高于其他流量的样品.因此可以通过优化AlGaN电子阻挡层的掺杂浓度,来显著提高多量子阱蓝光发光二极管的电学性能和光学性能.     

应变InGaAs/GaAs量子阱MOCVD生长优化及其在980 nm半导体激光器中的应用

使用低压MOCVD生长应变InGaAs/GaAs 980 nm量子阱.研究了生长温度、生长速度对量子阱光致发光谱(PL)的影响.并将优化后的量子阱生长条件应用于980 nm半导体激光器的研制中,获得了直流工作下,阈值电流为19 mA,未镀膜斜率效率为0.6 W/A,输出功率在100 mW的器件.     

阱宽对GaAs/Al0.3Ga0.7As量子阱红外探测器光谱响应的影响

采用金属有机物化学气相沉积法(MOCVD)生长 了两种不同结构参数的GaAs/Al0.3Ga0.7As红外量子阱材料, 利用傅里叶光谱仪,分别对阱宽为4.5与5.0nm的样品进行77K液氮 温 度下光谱响应测试及室温光致发光(PL)光谱 测试,样品的峰值响应波长分别为8.39、7.69μm,与根据薛定谔方 程计算得到 的峰值波长8.92、8.05μm的误差分别为6.36%、4.70%。对吸收峰向高能方向发生漂移的现象进行了分析讨论,认为势阱变窄时阱中的 应 力作用较强是导致峰值波长红移的原因,而与GaAs阱中进行适度Si掺杂无关。PL实验结果与 理论计算相符合,表明增加阱宽是量子阱带间跃迁能量升高的原因。据此可实现对量子阱能 级的微调,从而满足对不同波长探测的需要。     

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.