玻璃基底上氧化铟锡薄膜的光致发光性能

用直流磁控溅射法在190℃玻璃基底上制备了氧化铟锡(ITO)薄膜,利用荧光分光光度计研究了ITO薄膜的光致发光性能。结果表明,室温下ITO薄膜在波长250 nm光源的激发下,分别在467 nm和751 nm处观察到了发光强度较强的蓝光宽带和强度较弱的红光带。上述发光峰的出现分别和ITO薄膜中的氧空位、铟空位等缺陷在禁带中形成的能级有关,其中氧空位形成的施主能级位于导带下1.2 eV处,而铟空位形成的受主能级位于价带下1.65 eV处。     

ZnO及其缺陷电子结构对光谱特性的影响

利用全势LMTO(FP-LMTO)理论计算方法,对ZnO中的某些缔合缺陷(如氧空位和锌填隙、锌填隙和锌空位及锌的氧反位缺陷)的电子结构进行了计算.根据本文和以前的计算结果,得到了ZnO中几种本征点缺陷对应的缺陷态能级位置.利用得到的理论计算结果,我们分析了ZnO的吸收和发射光谱可能产生的机制,并讨论了ZnO与缺陷电子结构对它们的影响.     

Hg1—xCdxTe材料中的Te离子空位共振能级

利用拉曼显微镜在室温下对金属有机化合物气相外延（MOVPE）和液相外延（LPE）方法生长的Hg1-xCdxTe薄膜材料以及用加速坩埚旋转布里奇曼（ACRT－Bridgman)和Te溶剂方法生长的Hg1-xCdxTe体材料进行了系统研究，在上述4种方法生长的材料的显微拉曼光谱中，均发现在导带底上方且远高于材料导带底对应能级的显微荧光发光峰，通过详细比较可以判定，高于导带底约1．5eV的显微荧光起源于Hg1-xCdxTe材料中的Te离子空位与材料导带底的共振能级发光，从而确定在碲镉汞材料中存在一个稳定的Te离子空位共振能级。     

MgAl_2O_4绝缘性的第一性原理研究

基于密度泛函理论的第一性原理研究了存在本征空位和间隙缺陷的MgAl_2O_4体系。缺陷形成能的结果表明,O_(i4)和V_O分别在富氧(O-rich)和缺氧(O-poor)条件下的形成能最低,两者均在体系中引入深能级,无法增强MgAl_2O_4的导电性。电子结构的结果表明,O_(i4)在价带顶和导带底均引入能级,V_O在禁带中引入深能级,分别存在这两种本征缺陷的MgAl_2O_4依然保持良好的绝缘性。     

Cu掺杂ZnO薄膜的结构及发光特性

采用溶胶-凝胶旋涂法在玻璃衬底上制备了不同Cu掺杂量的ZnO薄膜。用显微镜和X射线衍射(XRD)研究了Cu掺杂对ZnO薄膜形貌和微结构的影响。结果表明,制备得到的ZnO薄膜具有应变小和c轴择优取向。室温下测量了样品Zn1-xCuxO的光致发光(PL)谱,发现所有样品的PL谱中均观察到435nm左右的蓝光发光带,发光带强度与Cu的掺杂量有关;当x=0.06时,Zn1-xCuxO薄膜的PL谱中出现了较强的蓝光发射。分析了掺杂量对发光性能的影响,并对样品的发光机制进行了探讨,推断出蓝光峰来源于电子由导带底到锌空位(VZn)能级的跃迁及锌填隙(Zni)能级到价带顶的跃迁,它们可通过改变Cu的掺杂量予以控制。     

非掺杂n型氮化镓外延层的光致发光

研究了热处理对非掺杂n型氮化镓外延层光致发光谱的影响和光谱中各发光带强度与温度之间的关系．热处理后,光谱中的带边峰和黄光峰的强度较热处理前都有明显降低．黄光峰强度随温度升高的衰减速度要比带边峰慢得多．由这些实验结果得出结论：光谱中的带边峰是由自由激子和束缚在一浅施主能级的束缚激子的谱线重合而成,这个浅施主能级很有可能是由氮空位产生;黄色荧光的机制应为自由电子或施主能级向深受主能级的跃迁,并且黄色荧光肯定和氮化镓中的一内部缺陷产生的深受主能级有关,该内部缺陷很有可能是镓空位．     

退火对大剂量Al离子注入GaN发光特性的影响

首次报道了用不同浓度的Al离子注入于蓝宝石衬底上的GaN薄膜（注入能量为500keV、注入浓度为10^14-10^15cm^-2），在做了不同温度和不同时间的快速热退火处理以及常规热退火处理后，在12K下用He-Cd激光（325nm）激发得到其发射谱。结果显示，经大剂量Al注入后的样品，其光致发光谱中3.45eV的带边激子发光以及2．9－3．3eV的4个声子伴随峰消失，此表明大剂量Al注入对GaN的晶体结构造成严重的损伤，以致本征发光消失。经10^14cm^-2剂量Al注入后的样品，在N2气氛中退火处理后，2．2eV缺陷发光峰得到了一定程度的恢复。而且，经常规退火处理后，此发射峰比快速退火处理的样品发射峰恢复得更好（其积分光强高3倍）。相似的结果亦显示于10^15cm^-2浓度的Al注入的样品。2.2eV黄色荧光源于GaN的缺陷(如Ga空位VGa)，或VGa-H2,或VGa-ON复合体），其能级位于价带顶以上约1.1eV处。荧光发射可以来自“导带－缺陷能级”的跃迁，也可能来自浅施主（如N位O，能有位于导带下－10meV）至上述缺陷能级之间的跃迁。I－V测量显示，Al的注入区成为－10^12Ω.cm^-1高阻膜，这表明Al的注入可能产生了某种深的电子陷阱，由于电子陷阱可俘获导带电子，导致发光猝灭，而退火可使与黄色荧光相关的缺陷得到部分恢复，因而2.2eV发射峰有所恢复。     

高阻n型硅的电子辐照

研究了高阻区熔和直拉单晶(扩铝)的P~+n管经电子辐照后产生的缺陷能级和它们的退火特性.区熔单晶中辐照生成的主要缺陷能级为 E:-0.43eV (双空位)和 E_v+ 0.49eV.在300℃退火后,这些能级的浓度与未退火前基本相同.直拉单晶中辐照生成的缺陷能级为E_c-0.18eV (氧空位对)和 E_v+ 0.49eV.在200℃以上退火后,氧空位明显减小并在300℃消失.     

N掺杂和氧空位对PbTiO3电子结构和导电性的影响研究

用第一性原理计算了P型N掺杂PbTiO3的电子密度差分、能带结构和态密度,讨论了氧空位对N掺杂PbTiO3性能的影响。在PbTiO3中掺杂N杂质后,PbTiO3的价带向高能级发生移动,费米能级进入价带顶部,带隙变窄,N掺杂PbTiO3表现出典型的P型半导体性能。当N掺杂PbTiO3中含有氧空位时,导带发生下移,受主被完全补偿。计算结果与实验数据相吻合。     

钒受主能级在n型4H-SiC中的深能级瞬态傅里叶谱和光致发光

借助深能级瞬态傅里叶谱研究了钒离子注入在SiC中引入的深能级陷阱.掺人的钒在4H-SiC中形成两个深受主能级,分别位于导带下0.81和1.02eVt处,其电子俘获截面分别为7.0 × 10-16和6.0×10-16cm2.对钒离子注入4H-SiC样品进行低温光致发光测量,同样发现两个电子陷阱,分别位于导带下0.80和1.6eV处.结果表明,在n型4H-SiC掺入杂质钒可以同时形成两个深的钒受主能级,分别位于导带下0.8±0.01和1.1±0.08eV处.     

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.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.