多孔硅表面Ag层对吸附其上的若丹明B染料分子表面增强Raman散射的影响

采用溶液电镀方法在多孔硅表面制备纳米尺寸的银颗粒,测量了不同镀银多孔硅表面吸附的ＲｈＢ染料分子以及固态的ＲｈＢ染料的Ｒａｍａｎ散射谱。在相同的激发强度下,固态ＲｈＢ染料的Ｒａｍａｎ散射最弱,而镀银的多孔硅表面具有明显的增强效果（～１０＾４）。     

稀氢氟酸中硅表面氢终端的原位拉曼光谱研究

本文用共焦显微拉曼系统原位观察了Ｓｉ（１００）表面氢终端原子在稀氢氟酸中的变化过程。研究表明：在硅片浸入氢氟酸溶液的初期,表面主要被硅和三个氢原子的结合体（Ｓｉ Ｈ３）以及硅和两个氢原子的结合体（Ｓｉ Ｈ２）所覆盖。随着腐蚀过程的延长,Ｓｉ Ｈ３越来越少,Ｓｉ Ｈ２的信号不断增强,并且,硅和单个氢原子的结合体（Ｓｉ Ｈ）的信号也开始出现。最终,硅表面主要被Ｓｉ Ｈ２所覆盖,有少量Ｓｉ Ｈ３和Ｓｉ Ｈ键。本文还表明,拉曼光谱用来原位观察半导体材料表面终端原子键在溶液中的变化是很有用的工具     

High Efficiency Electrically-Addressable Phase-Only Spatial Light Modulator

To realize a high efficiency electrically addressable phase-only modulator, we have coupled a liquid crystal display (LCD) to an optically addressed parallel-aligned nematic liquid crystal spatial light modulator (PAL-SLM) with a set of lenses. Phase modulation exceeding 3ϖ at 532 nm wavelength was obtained. We obtained linear transfer characteristics for phase modulation at various desired phase levels after calibration and adjustment of the transfer characteristics of the PAL-SLM and the LCD. Diffraction efficiency of 40% for binary phase grating and of 90% for 8-level blazed phase grating, which were very close to the simulation values, were observed. The power loss of the readout light was caused when passed through a half mirror, therefore, we examined a setup using an oblique readout light at the modulator. Very high diffraction efficiency was obtained from the setup by optimizing the polarization direction and optical path for this light, and the orientation of liquid crystals. Since the modulator can perform at better than 90% diffraction efficiency and at nearly 100% reflectivity, various high efficiency systems utilizing such modulators are expected.     

半导体硅片表面缺陷光反射“魔镜”检测技术

本文报道应用古代“魔镜”成像原理和现代激光技术发展起来的一种新的光反射“魔镜”检测技术。采用这项技术可以非常直观,方便地观测到直径小于１５０ｍｍ的硅抛光片及硅外延片表面存在的缺陷情况,其分辨率为０．５μｍ,由于光反射“魔镜”检测技术是一种新型的光学无损检测技术,具有探测灵敏度高,快速,无破坏性,大面积检测等优点,该项技术检测将会有更加广泛的应用前景。     

Development of dry processing techniques for CdZnTe surface passivation

A method for passivating the surface of Cd_1−xZn_xTe (CZT) x-ray and gamma ray detectors using relatively simple dry processing techniques has been developed. Leakage currents were significantly reduced for several processing methods. CZT samples were exposed to an oxygen plasma and/or coated with a reactively sputtered silicon nitride layer. Several parameters of the oxygen plasma step were found to be important for achieving enhanced surface resistivity. SiN_X has been previously characterized and was used because of its high dielectric quality and low deposition temperature. Reduction in leakage current after passivation by a factor of as much as twenty is demonstrated. Results are also presented which give a measure of the long-term stability of the passivating layers.     

多孔硅表面冷电子发射的研究

本文研究了多孔硅二极管表面发射电子的特性。ＰＳ二极管由薄金膜、ＰＳ层、ｎ型Ｓｉ衬底和欧姆接触铝背电极组成。在真空中,当在金属电极和铝背电极间加适当高的正电压且在收集极板和金电极间存在高外电场时,伴随着可见光,电子均匀地穿过金膜出来。电子发射的机理基于ＰＳ层外表面附近的强场效应。     

HETEROJUNCTION DIODES OF POROUS SILICON WITH SOLUBLE POLYANILINE*

Two kinds of heterojunction diodes of porous silicon (PS) with soluble polyaniline (PANI) werefabricated. One is a heterojunction diode of PS with water-soluble copolymer of polyaniline (PAOABSA),Al/PS-PAOABSA/Au cell as rectifying diode. Another is a heterojunction diode of PS with solublepolyaniline doped with DBSA, Al/PS-PANI (DBSA)/Au cell as light emitting diode (LED). The rectifyingcharacteristics of the rectifying diodes were measured as a function of the degree of sulfonation and thicknessof the copolymers, as well as oxidation of PS. The rectifying ratio of the heterojunction can reach 5.0×10~4 at±3 V bias. For the LED, the photoluminescence (PL) and electroluminescence (EL) spectra were measuredand discussed.     

RECTIFYING EFFECT OF POLYANILINE(PANI)/N-TYPE POROUS SILICONE HETEROJUNCTION*

Heterojunctions between polyaniline (PANI) and n-type porous silicon (PS), Al/PS-PANI/Au cell,were fabricated, and the rectifying parameters of this heterojunction diode were measured as a function of thepreparation conditions of PANI and PS, the electronic structure of PANI as well as cell structure. Therectifying parameters of Al/PS-PANI/Au cell were determined to be γ= 1 .8×10~1～ 1 .0×10~5 for the rectifyingratio at 3V, n = 3 ～12 for the ideal factor,j_0 = 8.0×10~(-5)～5.6×10~(-2) mA/cm~2 for the reversed saturated currentdensity, and φ_b = 0.67～ 0.83 V for the barrier height, respectively. The best rectifying heterojunction diodemade between PANI and n-type PS with higher rectifying factor (γ= 1 .0×10~5 at 3V ), output current (>1500mA/cm~2 at 3V) and lower ideal factor (n = 3.3) was obtained by preventing the oxidation of PS beforeevaporating Al electrode.     

Optical properties of nanocrystalline silicon embedded in SiO2

Nanocrystalline silicon embedded SiO₂ matrix has been formed by annealing the a-SiO_x films fabricated by plasma enhanced chemical vapor deposition technique. Absorption and photoluminescence spectra of the films have been studied in conjunction with micro-Raman scattering spectra. It is found that absorption presents an exponential dependence of absorption coefficient to photon energy in the range of 1.5–3.0 eV, and a sub-band appears in the range of 1.0–1.5 eV. The exponential absorption is due to the indirect band-to-band transition of electrons in silicon nanocrys-tallites, while the sub-band absorption is ascribed to transitions between surfaces and/or defect states of the silicon nanocrystallites. The existence of Stokes shift between absorption and photoluminescence suggests that the phonon-assisted luminescence would be enhanced due to the quantum confinement effects.     

半导体硅上激光诱导化学沉积镍薄膜

由于激光具有高能量密度、高单色性以及良好的相干性,在表面处理技术中的应用越来越广泛．在金属、半导体和高聚物基体上,从水溶液进行激光诱导的化学沉积引起了人们的极大注意,这种工艺在微电子电路及器件上有广泛的应用前景．与传统的化学镀相比,它具有明显的优越性...