氢在α-石英中扩散的从头算分子动力学

采用从头算分子动力学研究在不同温度(300 K,700 K,1 000 K,1 200 K)下氢原子在α-石英中的扩散机制，根据爱因斯坦方程计算氢原子的扩散前项因子D0(7.72×10-4 cm2/s)和活化能(0.078 eV)。研究结果表明，氢原子在α-石英中的扩散路径有2种。低温下氢原子主要在由硅和氧原子组成的腔中做随机运动，直到跨过一个环到另外一个腔。同时研究温度在1 500 K时氢原子的扩散，氢在周围的3个氧原子之间发生跳跃，导致扩散过程中出现了3种缺陷结构，缺陷结构之间可以相互转化。本文研究在微电子器件可靠性分析等方面有应用价值。     

气溶胶沉降扩散研究进展(特邀)

气溶胶沉降扩散主要研究气溶胶粒子在大气中的运动状态、浓度迁移、表面沉积过程。表征物理量主要包括气溶胶粒子沉降通量、沉降速度、浓度分布、扩散速度等。开展相关研究可以为气溶胶生成方式优化、消光效果评估与预测等提供科学依据。文中概括了三种气溶胶生成方式，分析了气溶胶粒子在大气中沉降扩散过程机理，阐述了气溶胶沉降与扩散特性参量计算、仿真模拟和试验测定方法。结合目前气溶胶沉降扩散研究面临的挑战，对气溶胶沉降扩散理论分析、数值模拟、试验研究与综合运用进行了展望。     

用Columnar模型对电子空穴对复合逃逸产额的模拟计算

用一种比较简单的Jaffe近似方法计算了质子在SiO2中的电子空穴对的逃逸率,讨论了辐照偏置、电场、质子入射角度、质子能量等对逃逸产额的影响.得到了电子空穴对复合逃逸率与质子能量、电场成正比的结果.计算结果与实验结果的比较,说明了Jaffe近似方法可以比较正确地描述质子在二氧化硅中的总剂量效应.     

用Columnar模型对电子空穴对复合逃逸产额的模拟计算

用一种比较简单的 Jaffe近似方法计算了质子在 Si O2 中的电子空穴对的逃逸率 ,讨论了辐照偏置、电场、质子入射角度、质子能量等对逃逸产额的影响 .得到了电子空穴对复合逃逸率与质子能量、电场成正比的结果 .计算结果与实验结果的比较 ,说明了 Jaffe近似方法可以比较正确地描述质子在二氧化硅中的总剂量效应 .     

多孔硅技术在硅基微型燃料电池中的应用

多孔硅作为一种新型材料，利用其疏松多孔的特性及与IC加工的兼容性，将其用于硅微质子交换膜燃料电池的研究中，作为其电极扩散层，对多孔硅膜的性能、制备工艺及多孔硅膜表面金属淀积工艺进行了研究，提出一套基于MEMS加工技术和薄膜淀积技术的制作硅微质子交换膜燃料电池的工艺。     

缓冲质子源LiNbO3波导折射率计算及实验

为实现铌酸锂退火质子交换(APE)波导折射率分布的准确计算,选择含苯甲酸锂的苯甲酸缓冲液作为质子交换质子源,高温退火制作了波导样本.针对该工艺过程建立退火质子交换波导模型,包括非线性扩散模块和光学数值仿真模块,分别计算APE波导折射率及其模式有效折射率.以测得的样本波导模式有效折射率和计算的有效折射率差的均方根构建评价函数(FOM),结合遗传算法提取该工艺条件下质子扩散参数,实现了不同交换深度和退火时间波导折射率分布及其光学特性的一体化计算.实验表明:FOM小于0.001,计算折射率分布同IWKB方法测得结果吻合较好,最大偏差约0.002.     

北京正负电子对撞机次级束质子单粒子翻转计算和试验研究

北京正负电子对撞机(BEPC)电子直线加速器试验束打靶产生的次级束中包含质子,其中能量约为50MeV~100MeV的质子占有很大比例,这弥补了国内高能质子源的空白。本工作计算得到次级束中的质子能谱,建立质子单粒子翻转截面计算方法,在北京正负电子对撞机次级束质子辐射环境中,计算静态随机存取存储器的质子单粒子翻转截面,设计了SRAM质子单粒子翻转截面测试试验,发现SRAM单粒子翻转和注量有良好的线性,这是SRAM发生单粒子翻转的证据。统计得到不同特征尺寸下SRAM单粒子翻转截面,试验数据与计算结果相符,计算和试验结果表明随着器件特征尺寸的减小器件位单粒子翻转截面减小,但器件容量的增大,翻转截面依然增大,BEPC次级束中的质子束可以开展中高能质子单粒子效应测试。     

全息法研究LN和Mg:LN晶体波导基片的光损伤

本文报道了用全息法研究铌酸锂(LN)晶体和掺镁铌酸锂(Mg:LN)晶体波导基片光损伤的结果。分别采用钛扩散和质子交换工艺制作波导基片;其中Mg:LN晶体波导基片的抗光损伤能力高于LN基片,质子交换波导片的抗光损伤能力高于钛扩散波导片。     

LiNbO3质子交换光波导偏振器的研究

研制了632.8 nm光波段X切Y传Ti扩散铌酸锂质子交换光波导偏振器.从理论上分析了钛(Ti)扩散及质子交换(PE)LiNbO3波导折射率改变机理,以及影响器件性能的各种因素.实验结果与理论计算符合良好,达到了集成光路中对器件的偏振要求,为其他类型偏振器的研制提供了理论依据.     

Ti:LiNbO_3质子交换光波导

本文研究了在Ti扩散LiNbO_3衬底上用苯甲酸质子交换制备光波导的方法,以及单模条件、折射率分布、交换系数、表面状态和热稳定性等问题。     

Conversion of Light to Electricity by Photoinduced Reversible pH Changes and Biomimetic Nanofluidic Channels

Inspired by living systems that have the inherent skill to convert solar energy into bioelectric signals with their light‐driven cross‐membrane proton pump, a photoelectric conversion system that can work in alkaline conditions based on photoinduced reversible pH changes by malachite green carbinol base and a smart gating hydroxide ion‐driven nanofluidic channel is demonstrated. In this system, solar energy can be considered as the only source of cross‐membrane proton motive force that induces diffusion potential and photocurrent flowing through the external circuit. The conversion performances are 0.00825% and 36%, which are calculated from the photoelectric conversion and Gibbs free energy diffusion, respectively. The results suggest that electric power generation and performance could be further optimized by selecting appropriate photosensitized molecules and enhancing the surface‐charge density as well as adopting the appropriate channel size. This facile, cost‐efficient, and environmentally friendly photoelectric conversion system has potential applications for future energy demands such as production of power for in vivo medical devices.     

基于不同介质材料的AOTF特性研究综述

基于不同介质材料的AOTF(声光可调谐滤波器)具有不同的性质及应用场合.目前应用于紫外、可见光和红外波段的AOTF主要以α-SiO2、TeO2和TAS( Tl3AsSe3)为介质.为了得到性能更优的AOTF,人们一直在探寻新型双折射晶体材料来代替α-SiO2和TAS.文章汇总并讨论了近年来人们针对基于TeO2、KDP(...     

Halogen diffusion on a Ga-stabilized ζ-GaAs(001)–(4 × 2) surface

The atomic and electronic structure of a Ga-stabilized GaAs(001) surface with the ζ(4 × 2) reconstruction and halogens in a number of symmetric sites on the surface are calculated by the plane-wave projector augmented wave method. The energy barriers of halogen-atom diffusion on this surface are calculated, which allow determination of the most preferred paths of their migration. It is shown that there is a low barrier (0.17–0.23 eV) for the diffusion of all halogens under consideration (I, Br, Cl, F) along the surface gallium dimer, whereas the barrier is significantly higher for diffusion between adjacent gallium dimers. In general, the energy barriers for halogen diffusion in both directions ([110] and [1-10]) point to their high surface mobility, despite high binding energies at a number of surface adsorption sites.     

Experimental research of heavy ion and proton induced single event effects for a Bi-CMOS technology DC/DC converter

This paper tested and analyzed heavy ion and proton induced single event effects (SEE) of a commercial DC/DC converter based on a 600 nm Bi-CMOS technology. Heavy ion induced single event transients (SET) testing has been carried out by using the Beijing HI-13 tandem accelerator at China Institute of Atomic Energy. Proton test has been carried out by using the Canadian TRIUMF proton accelerator. Both SET cross section versus linear energy transfer (LET) and proton energy has been measured. The main study conclusions are: (1) the DC/DC is both sensitive to heavy ion and proton radiations although at a pretty large feature size (600 nm), and threshold LET is about 0.06 MeV·mg/cm²; (2) heavy ion SET saturation cross section is about 5 magnitudes order larger than proton SET saturation cross section, which is consistent with the theory calculation result deduced by the RPP model and the proton nuclear reaction model; (3) on-orbit soft error rate (SER) prediction showed, on GEO orbit, proton induced SERs calculated by the heavy ion derived model are 4-5 times larger than those calculated by proton test data.     

Bio‐inspired Photoelectric Conversion Based on Smart‐Gating Nanochannels

Inspired by the light‐driven, cross‐membrane proton pump of biological systems, a photoelectric conversion system based on a smart‐gating, proton‐driven nanochannel is constructed. In this system, solar energy is the only source of cross‐membrane proton motive force that induces a diffusion potential and photocurrent flowing through the external circuit. Although the obtained photoelectric conversion performance is lower than that of conventional solid photovoltaic devices, it is believed that higher efficiencies can be generated by enhancing the protonation capacity of the photo‐acid molecules, optimizing the membrane, and synthesizing high‐performance photosensitive molecules. This type of facile and environmentally friendly photoelectric conversion has potential applications for future energy demands such as the production of power for in vivo medical devices.     

Deep-level defects and diffusion length measurements in low energy proton-irradiated GaAs

A detailed characterization of deep-level defects induced by low energy proton irradiation in n-GaAs LPE layer using AlGaAs-GaAs mesa structure has been carried out for several proton energies (i.e., 50 100 and 290 kev) and fluences (i.e., 10¹⁰, 10¹¹, and 10¹² p/cm²), using DLTS, SEM-EBIC, I-V and C-V measurement techniques. Important defect and recombination parameters such as density and energy level of electron and hole traps, thermal emission rates and capture cross sections for electrons and holes in each trap level as well as hole diffusion lengths in the n-GaAs LPE layer were deduced from these measurements. Hole diffusion lengths determined by the EBIC, DLTS, and I-V measurements are found in good agreement. It is shown that dark current under forward bias condition was dominated by recombination of electron-hole pairs via deep level defects in the junction space charge region of the diode. Significant carrier removal occurs for proton fluence greater than 10¹³p/cm². Research supported by NASA Langley Research Center under grant No. NSG-1425.     

Threshold control in VCSELs by proton implanted depth

The proton implantation is one of key procedures to confine the current diffusion in vertical cavity surface emitting lasers(VCSELs),in which the proton implanted depth and profile are main parameters.Threshold characteristics of VCSELs with various proton implanted depths are studied after optical,electrical and thermal fields have been simulated self-consistently in three dimensions.It is found that for VCSELs with confinement radius of 2 mm,increasing proton implanted depth can reduce the injected curren...