多孔硅上生长Ge量子点的光学特性

采用量子尺寸的多孔硅作为衬底,利用区域优先成核在多孔硅表面上成功地生长了Ge量子点.由于量子限制效应锗的PL谱发生了明显的蓝移,计算表明在傅里叶红外光谱中观察到的中红外(5-6μm)吸收峰是源于量子点中的亚能带跃迁(两个重空穴能级之间的跃迁),这为Ge量子点红外光探测器的应用提供了理论基础.     

有Si覆盖的部分氧化多孔硅的光致发光

在488nm的Ar+激光激发下,Si覆盖的部分氧化多孔硅(POPS)的光致发光谱(PL)在1.78eV处展示了一个稳定的PL峰,它的强度达到刚制备多孔硅的发光强度.使用X射线衍射、Raman散射、傅里叶变换红外吸收和电子自旋共振等对其发光机理进行了系统的研究.结果表明,这个增强的PL峰不是起源于量子限制硅晶粒中的带带复合,也不是起源于样品表面局域态或硅晶粒与氧化物之间的界面态的辐射复合.通过与Ge覆盖的部分氧化多孔硅的相关结果比较,我们认为这个稳定增强的PL峰起源于氧相关缺陷中心的光学跃迁.     

半导体纳米结构的新光电子学性质

纳米光子学国际会议于 1 999年 3月在俄罗斯科学院微结构物理研究所的所在地下诺夫戈罗德举行。这已是有关半导体纳米结构物理的第二次会议。第一次会议于 1 998年召开。会上讨论两个方向的现状。第一 ,与以硅 (Si Ge、Si/A3B5、Si/Ge/C、Si/Ge/Sn、Si/Si O2 量子阱和量子点 )、多孔硅和含有稀土元素的纳米晶体硅为基础的异质结构的光电子学性质基础有关的物理现象 ,相应的纳米结构生长工艺和特性 ;第二 ,在具有量子阱的半导体结构中的热载流子在强电场和磁场中的非平衡、反转分布及带内光学跃迁的物理问题 ,包括反转机理和在中、远红…     

量子点红外探测器及焦平面阵列的研究进展

量子点红外探测器(QDIP)理论上具有对垂直入射光敏感、暗电流小、载流子寿命长、工作温度和响应率高等优势.目前,研究主要集中在普通量子点红外探测器、阱中点红外探测器(DWELL-QDIP)、隧穿量子点红外探测器(T-QDIP)、Si/Ge量子点红外探测器、二维小孔阵列红外探测器(2DHA-QDIP),国外报道了640×...     

量子点红外探测器研究进展

量子点红外光电探测器(QDIP)凭借自身的优点,未来很有可能与碲镉汞(HgCdTe)红外探测器、量子阱红外光电探测器(QWIP)和非制冷微测辐射热计相竞争。目前,普遍采用自组织方法生长量子点,研究主要集中在:①隧道量子点红外探测器(T-QDIP);②量子阱中量子点(DWELL)红外探测器;③Si基QDIP;④Ge QDIP。本文阐述正在研究的几种QDIP,并对下一代传感器用QDIP进行预测。     

多孔硅中电子光跃迁过程的研究

用硅-氧化硅复合纳米材料的能带混合模型研究了多孔硅中的各类电子状态。分析了各种状态的能带属性及其量子限制特性，从而解释了实验中观察到的量子限制态和非量子限制态。在有效质量理论框架下计算了不同能级间的光跃迁矩阵元，得出了带内和带间状态间的跃迁选择定则。运用所计算的结果较好地解释了实验中观察到的PL和CL光谱中的量子限制态、非量子限制态、元激发陷阱以及各种不同的谱峰。最后从多孔硅发光特性与半导体材料及杂质、缺陷发光的对比中阐明了这种纳米发光材料的特征。由此笔者提出了研究硅一氧化硅复合纳米材料来开发新的硅基发光材料、器件和集成电路的新途径。     

Ge/Si量子点的控制生长

采用离子束溅射技术,在生长了Si缓冲层的硅晶片上制备了一系列Ge量子点样品.借助原子力显微镜(AFM)和Raman光谱等测试手段研究了Ge/Si量子点生长密度、尺寸及排列均匀性的演变规律.结果表明,改变Si缓冲层厚度及其生长方式,可以有效控制量子点的尺寸、均匀性和密度.随缓冲层厚度增大,量子点密度先增大后减小,停顿生长有利于提高缓冲层结晶性,从而提高量子点的密度,可以达到1.9×1010 cm-2.还研究了Si缓冲层在Ge量子点生长过程中的作用,并提出了量子点的生长模型.     

Si(001)斜切衬底上Ge量子点的固相外延生长

研究了Si(001)面偏[110]方向6°斜切衬底上Ge量子点的固相外延生长.实验结果表明,在Si(001)6°斜切衬底上固相外延生长Ge量子点的最佳退火温度为640℃,在斜切衬底上成岛生长的临界厚度低于在Si(001)衬底成岛生长的临界厚度,6°斜切衬底上淀积0.7nm Ge即可成岛,少于Si(001)衬底片上Ge成岛所需的淀积量.从Ge量子点的密度随固相外延温度的变化曲线,得到Ge量子点的激活能为1.9eV,远高于Si(111)面上固相外延Ge量子点的激活能0.3eV.实验亦发现,在Si(001)斜切衬底上固相外延生长的Ge量子点较Si(001)衬底上形成的量子点的热稳定性要好.     

多孔硅中的新量子限制态和PL光谱

由大量ＰＬ和ＰＬＥ光谱的实验分析得出多孔硅的发光既具有纳米硅中带带跃迁的特征，又受不同表面状态的制约．本文从多孔硅表面化学键叠加构成二维界面势的模型出发提出了表面化学键制约量子限制态．用简单的有效质量计算模型求出了这种新量子态的能级、能谷混合系数、电子波函数及跃迁选择定则、通过这种新量子态解释了多孔硅ＰＬ和ＰＬＥ光谱的实验特性．     

Si(001)斜切衬底上Ge量子点的固相外延生长

研究了Si(001)面偏[110]方向6°斜切衬底上Ge量子点的固相外延生长.实验结果表明,在Si(001)6°斜切衬底上固相外延生长Ge量子点的最佳退火温度为640℃,在斜切衬底上成岛生长的临界厚度低于在Si(001)衬底成岛生长的临界厚度,6°斜切衬底上淀积0.7nm Ge即可成岛,少于Si(001)衬底片上Ge成岛所需的淀积量.从Ge量子点的密度随固相外延温度的变化曲线,得到Ge量子点的激活能为1.9eV,远高于Si(111)面上固相外延Ge量子点的激活能0.3eV.实验亦发现,在Si(001)斜切衬底上固相外延生长的Ge量子点较Si(001)衬底上形成的量子点的热稳定性要好.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.