A NEW METHOD TO ENHANCE THE MAGNETISM OF Fe OVERLAYER ON GaAs(100): SULFUR PASSIVATION USING CH3CSNH2

Ferromagnetic resonance (FMR) has been used to investigat the magnetism of Fe overlayer on S-passivated GaAs(lO0) pretreated by CH₃CSNH₂. Comparing with the magnetism of Fe overlayer on clean GaAs(100), we find that sulfur passivation can prevent Aa diffusion into Fe overlayer and weaken the interaction of As and Fe. It results in enhancing the magnetism of Fe overlayer on GaAs(100). We also investigate the effects of the pre-annealing of S- pasaivated GaAs(100) substrate on the magnetism of Fe overlayers. The results show that the maximum effective magnetization can be obtained at annealing temperature of 400℃. According to the experimental results of synchrotron radiation photoemission, it can be explained by the change of chemical composition and surface structure of the passivation layer on GaAs(100) surface after the annealing.     

PASSIVATION OF THE InP(100) SURFACE USING (NH4)2Sx

InP(100) surface treated with (NH₄)₂S_x has been investigated by using photolumines-cence(PL), Auger electron spectroscopy and X-ray photoelectron spectroscopy, It is found that PL intensity increased by a factor of 3.3 after (NH₄)₂S_x passivation and the sulfur remained on the surface only bonded to indium, not to phosphorus. This suggests that the sulfur atoms replace the phosphorus atoms on the surface and occupy the phosphorus vacancies.     

STUDY OF IRON OVERLAYER ON SULPHUR PASSIVATED GaAs(100) BY SYNCHROTRON RADIATION PHOTOEMISSION

We have studied the interface electronic structures and the chemical reaction of the Fe overlayer deposited on S-passivated GaAs(100). The chemical bond and electronic structure are different from Fe/GaAs, and the reaction between As and Fe is weakened by S atoms. This is beneficial to the magnetism in the interface. In the first stage of deposition, Fe clusters is form near S atoms due to the large electronegativity of S. The S atoms remain at the interface with Fe coverage. Magnetic ordering feature is found at a coverage higher than 0.6 nm. According to the large exchange splitting in valence band spectra, we suggest that Fe phase transition from bcc to fcc occurs with increasing coverage.     

多孔硅的一种新的后处理方法──微波等离子体辅助钝化处理

报道了对多孔硅进行后处理的一种新方法，即真空中微波等离子体辅助的钝化处理．傅里叶变换红外吸收谱表明，经处理的样品表面主要是被SiS_x和SiO_y所覆盖．与未经处理的样品相比，其发光强度增加约3.5倍，PL峰位蓝移了40nm，而且在空气条件下存放60d后发光强度没有变化．表明这种方法是增加多孔硅发光强度和提高稳定性的有效方法之一．     

提高相干谐波输出的一种新方法

本文利用自由电子激光(FEL)纵模统一理论讨论了光学速调管自由电子激光相干谐波的输出情况。从物理上分析了非对称光学速调管的设计,得出了采用非对称的光学速调管可使FEL的相干谐波输出提高近30％。     

硫在镍(100)表面偏析动力学研究

本文使用AES-LEED联合装置研究了650—800℃温度范围内硫在镍(100)表面上的偏析动力学。结果表明,在较短退火时间内硫的表面浓度正比于退火时间的平方根,与McLean的动力学模型是一致的。扩散系数与温度的关系为D(cm²/s)=5×10^-3exp(-44600/RT)。硫偏析在镍(100)表面达到饱和值,LEED观察指出形成了硫的c(2×2)结构。深度剖面分析,硫/镍俄歇峰高比随氩离子剥离时间指数降低。 关键词：     

PASSIVATION OF THE InP(100) SURFACE USING (NH4)2Sx

InP(100) surface treated with (NH₄)₂S_x has been investigated by using photolumines-cence(PL), Auger electron spectroscopy and X-ray photoelectron spectroscopy, It is found that PL intensity increased by a factor of 3.3 after (NH₄)₂S_x passivation and the sulfur remained on the surface only bonded to indium, not to phosphorus. This suggests that the sulfur atoms replace the phosphorus atoms on the surface and occupy the phosphorus vacancies.     

消除强背景辐射干扰的光电探测新方法

 以InSb探测器(PV型)为例, 通过建立载流子输运的动力学模型得到光生电动势与入射光功率密度的函数关系, 提出了一种消除强背景辐射对光电探测的影响的新方法, 并且通过实验证实了这种方法的有效性及其理论模型的合理性。与传统的调零法相比, 该方法精度较高且能适用于更高强度的背景辐射 。     

用倒频谱技术消除声反射影响的方法

现场测量声信号需要消除因声反射而产生的干扰。本文根据传声通道的响应特性,提出一种用倒频谱技术消除声反射影响的方法。计算机模拟和在消声室进行的自由场与人为设立一、两个反射面情况的对比实验都表明,该方法有效。     

CH_3CSNH_2钝化对铁磁金属与GaAs界面扩散的影响

通过实验对比 ,研究了CH3CSNH2 钝化对铁磁金属与GaAs界面处As扩散行为的影响 .发现S钝化处理改变了表面As元素的化学环境 ,减弱了As元素向铁磁金属外延层中的扩散现象 ,削弱了As与铁磁金属的反应 ,形成了较窄的反应层 ,并且改善了界面磁性 .初步探讨了S钝化影响As扩散的原因 .     

一种产生Einstein约化场方程解的方法

本文给出了在Ernst场方程的解空间上的一种新变换,并且研究了这种变换与Ernst场方程解之间的关系。证明了在这种变换下,Ernst场方程是不变的,即由我们的这种变换可产生Ernst场方程的新解。最后还讨论了这种变换与Virasoro代数的关系。 关键词：     

测量线胀系数的一种新方法

给出测量金属线胀系数的一种新方法。本文根据夫琅和费衍射原理，利用CCD来测量金属体随温度升高的伸长量，对黄铜的线胀系数进行了测量。     

复杂网络上动力系统同步的研究进展Ⅱ——如何提高网络的同步能力

本文在上一篇综述的基础上,详细介绍了2005年以来复杂网络上动力系统同步研究的最新进展,特别着重于如何提高网络同步能力方面的研究.文章首先介绍了最近有关网络结构与同步能力之间细致关系的研究,然后重点介绍了提高复杂网络同步能力的两种方法:调节耦合强度和改变网络结构,文章最后回答了上一篇综述提出的几个问题,并指出了这一领域几个新的有待解决的问题和可能的发展方向.     

研究界面多相吸附动力学的一个新方法——表面增强喇曼散射方法

提出利用表面增强喇曼散射(SERS)效应研究化学吸附动力学,给出了理论模型和实验方法。研究了结晶紫(CV)和对氨基苯甲酸(PABA)在银镜及银胶表面吸附。发现在银镜和银胶表面上,CV的吸附是匀相的,PABA则是多相的;表面形态的差异不影响表面多相因子和脱附速率常数(K_d=0),只对吸附速率常数有影响。讨论了表面多相因子的意义。 关键词：     

GaAs(100)表面硫钝化的新方法:CH3CSNH2/NH4OH处理

建立了一种硫钝化GaAs(100)表面的新方法,即CH₃CSNH₂/NH₄OH溶液处理,应用同步辐射光电子能谱(SRPES)和X射线光电子能谱(XPS)表征了该钝化液处理的n-GaAs(100)表面的成键,特性和电子态.结果表明,经过处理的n-GaAs(100)表面,S既与As成键也与Ga成键,形成S与GaAs的新界面,并且Ga和As的氧化物被移走,这标志着CH₃CSNH₂/NH_{4关键词：}     

Laser projection-patterned etching of (100) GaAs by gaseous HCl and CH3Cl

Laser projection-patterned etching of GaAs in a HCl and CH₃Cl atmosphere performed using a pulsed KrF-excimer laser (=248 nm, =15 ns) and deep-UV projection optics (resolution 2 m) is reported. The etching process carried out in a vacuum system having a base pressure of 10^–6 mbar is shown to result from a purely thermochemical reaction. Etching takes place in two steps: (i) between the laser pulses, the etchant gas reacts with the GaAs surface-atomic layer to form chlorination products (mainly As and Ga monochlorides), (ii) local laser surface heating results in the desorption of these products allowing further reaction of the gas with the surface. The influence of the etching parameters (laser energy density, gas pressure and pulse repetition rate) on the etch rate and the morphology of the etched features was studied. Etch rates up to 0.15 nm per pulse, corresponding to the removal of 0.5 GaAs molecular layer, are achieved. The spatial resolution of the etching process is shown to be controlled by the heat spread in the semiconductor and by the nonlinear dependence of the etch rate on the surface temperature. As a result, etched features smaller or larger than the projected features of the photomask are achieved depending on the laser energy density. Etched lines having a width of 1.3 m were obtained at low fluences by the projection of 2 m wide lines onto the GaAs surface.     

确定SQM力场标度因子的新方法

建立了一种计算ＳＱＭ力场标度因子的新方法，它具有简捷、精确、且不依赖于实验信息的特点，改善了ＳＱＭ方法。将其在Ａｂｉｎｉｔｉｏ水平上计算的力常数用于振动分析，所得计算频率与观测频率十分吻合。     

ZnSe/GaAs(100)界面电子结构的计算

利用形式散射理论的格林函数方法，采用紧束缚最近邻近似下的sp³s模型，计算了ZnSe/GaAs(100)两类界面(Se/Ga和As/Zn界面)的电子结构.分别给出了两类界面的界面带结构和波矢分辨的层态密度及其分波态密度.计算结构表明，在ZnSe/GaAs(100)两类界面的禁带隙中均无界面态，而在其价带区均存在三条束缚的界面带和四条半共振带；通过比较，分析了两类界面的界面态特征及其来源. 关键词：     

金属氧化物对Ca(OH)_2脱硫影响的研究

1前言鉴于钙基吸收剂干法烟气脱硫技术在脱硫产物处理等方面的优势，本文开展了Ca（O）。中低温干燥状态下的反应特性、活化能及其影响因素的试验研究，以求进一步增强对其反应特性的了解并弄清金属氧化物的作用。2装置及样品试验装置如图1示，采用硫化床形式以强化吸收剂与气相反应物之间传质。床层温度由理入反应器内的热电偶测出并由温控仅控制。SOZ气体经稀释气体稀释并混合、预热后流入反应管进行反应，反应后气体由尾部的SOZ吸收水箱吸收后排入大气。冷却室可防止水蒸气进入气体分析仪。通过记录SOZ浓度随时间的变化规律即可得到…