单分子吸附在Cu(100)表面上的振动谱及其STM图像模拟

本文利用第一性原理方法对乙炔（C2H2）,苯（C6H6）和吡啶（C5H5N）及其离解物（CCH,C6H4和C5H4N等）吸附在Cu(100）表面时C－H伸缩振动频率进行了理论计算,同时还计算了H被D替代时的C－D伸缩振动频率,理论计算结果与STM－IETS给出的测量值相当吻合,基于Tersoff-Hamann理论模型,本文还模拟出这些小分子吸附在Cu(100)表面的STM图像,与实验图像的主要特征吻合。     

C_(90)分子单层膜在Au(111)表面的STM研究

在超高真空中使用热蒸发方法,在Au(111)表面上制备了C90分子的分子单层膜,并利用超高真空低温扫描隧道显微镜在120 K温度下对其结构进行研究。观察到C90分子在Au(111)表面上先是沿着台阶边缘生长,分子铺满一层后,会在薄膜上形成岛状结构。本文对岛状结构进行了原位高分辨表征,观察到C90分子在正偏压和负偏压下的几种不同形貌,并给出了各种形貌所对应的C90分子构型。     

C90分子单层膜在Au(111)表面的STM研究

在超高真空中使用热蒸发方法,在Au(111)表面上制备了C90分子的分子单层膜,并利用超高真空低温扫描隧道显微镜在120 K温度下对其结构进行研究.观察到C90分子在Au(111)表面上先是沿着台阶边缘生长,分子铺满一层后,会在薄膜上形成岛状结构.本文对岛状结构进行了原位高分辨表征,观察到C90分子在正偏压和负偏压下的...     

关于Ni（100）面上C复盖的LEED和STM研究

本文叙述了Ｃ／Ｎｉ（１００）系统的ＬＥＥＤ和ＳＴＭ的研究结果，并讨论了该系统的表面结构模型。     

Investigating local (photo-)current and structure of ZnPc:C60 bulk-heterojunctions

The performance of organic solar cells strongly depends on the nanoscale structure of the used mixed absorber layer. Utilizing photoconductive and conductive atomic force microscopy (pcAFM and cAFM), as well as transmission X-ray microscopy (TXM), we investigate the influence of different substrate temperatures T_sub on the thin-film structure and local photocurrent in bulk-heterojunctions (BHJs) of vacuum deposited zinc phthalocyanine (ZnPc) and Buckminsterfullerene (C₆₀) mixed absorber layers. In this paper, we present topography maps, photocurrent maps under short-circuit current conditions, dark-current maps, and TXM images with high lateral resolution down to 25 nm. We observe a strong influence of the substrate temperatures during deposition T_sub on the nanoscopical segregation of the two components in the BHJ. This segregation leads to a spatial extension of the dark-current and a reduced short-circuit current at higher substrate deposition temperatures T_sub.     

Dark current and photovoltage models on the formation of depletion region in C60/NPB organic heterojunctions

We establish quantitative models on the formation of depletion regions in organic photodiodes (OPD) based on fullerene/N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (C₆₀/NPB) heterojunctions. The models describe the relation of dark current and open-circuit voltage to the deposited thickness of C₆₀ or NPB. Interfacial electronic structures, such as built-in potential, the charge density, the minimized thicknesses of completely developed depletion regions and the energy level bending on each side of the heterojunction were derived from the fitting model. Also, we observed a shift of depletion region from NPB to C₆₀ due to the relative change of charge density under illumination. The device performance proved the reasonability of the models. This paper provides a universally applicable method to probe the interfacial information of organic semiconductors.     

Si(111)表面电子结构

本文利用自洽LMTO-ASA方法研究了晶体Si及Si(111)表面的几种模型的电子结构,给出了在slab模型各不同结构下的态密度和分波态密度,以及各不等价原子态密度和分波态密度,该结果与其它理论计算和实验结果相吻合     

Sn在Cu(111)上欠电位沉积的现场STM研究

本文用现场扫描隧道显微镜（in-situ STM)研究Sn在Cu(111）上的欠电位沉积（underpotential deposition UPD)过程,实验结果表明：Sn原子在Cu(111)表面上的UPD首先在晶面的边缘处发生,随后向晶面的其余地方发展并取代吸附在表面的SO4^2-,这一过程伴随着显著的台阶轮廓的变化,在Sn的UPD层溶出过程中,台阶边缘形状发生了更剧烈的变化。并且观察到凹洞的出现,表明Sn与Cu (111)基底形成了表面合金。     

A comparison of two air-stable molecular n-dopants for C60

We compare two air-stable n-dopants for the fullerene C₆₀: AOB and DMBI-POH. Conductivity and Seebeck coefficient measurements were performed at various doping concentrations and the thermal activation of the conductivity was determined. A superlinear increase of conductivity upon doping was found for DMBI-POH doped C₆₀ reaching a maximum conductivity of 5.3 S/cm. In contrast to this, a linear rise of conductivity and an exponential thermal activation of mobility was observed for C₆₀ doped by AOB. This suggests a different doping mechanism for the two compounds.     

C_(60),M@C_(60)电子传输特性研究

采用扩展的Hückel方法与格林函数方法,分析了双Au电极作用下,C60,M@C60(M=Si,Ge)富勒烯分子的电子结构与导电性,并对三种富勒烯分子的电子结构与电子输运特性进行了对比。研究结果表明,三种富勒烯分子与A u电极“接触”后,其最高占据分子轨道与最低未占据分子轨道间的能隙减小,它们与A u电极之间的结合既有共价键的成分,又有离子键的成分;三种富勒烯分子的电子输运性能依次具有Ge@C60>Si@C60>C60的顺序。     

半金属表面上酞菁锰分子的转动态研究

利用低温STM研究了半金属Bi(111)表面上单个酞菁锰分子的转动态。通过高分辨STM图发现,在液氮温度(77K)下单个酞菁锰分子呈六角形。利用STM操纵技术实现了对单个酞菁锰分子的制动,并通过对单分子的高低起伏和吸附构型分析,确定分子在Bi(111)表面做非连续的中心转动。这种单分子转动是三种相对稳定的吸附构型交替变化的结果。结合I-t谱技术,进一步验证了这三种分子吸附构型的存在;并利用近似统计分析方法得到三种吸附构型各自出现的概率以及其相对能量。     

Electronic structure and magnetic properties of Ca3Co2O6 cobaltites: Intrachain magnetic ordering

The present study is focussed on the intrachain magnetic interactions between the trigonal prismatic (TP) and octahedral (OCT) Co sites in Ca₃Co₂O₆ cobaltites from their electronic structure determined using the first principle full potential linearized augmented plane wave method within the GGA+U approximation. The occurence of various magnetic solutions as a function of the Coulomb integral U of the GGA+U approach is investigated. Various magnetic configurations, corresponding to different total magnetization, are found only when the insulating state is reached for U > 2.5 eV and the most stable solution corresponds to a magnetic spin moment on the TP (respectively OCT) site around 2.6 (respectively 1) Bohr magneton.     

Cr:Mg2SiO4晶体中络离子(CrO4)4-的自旋极化MS-Xα计算

本文采用自旋极化MS-Xα方法计算了Cr:Mg2SiO4晶体中络离子(CrO4)4-的电子结构,给出了Td群和C(3v)群下的单电子能量本征值、本征函数和自旋极化分裂值。用过渡态理论计算了部分光学跃迁和电荷转移跃迁的能量。采用Case-Karplus电荷分配法计算得到自旋-轨道耦合常数ζ(?)。讨论了配位体的距离对单电子轨道和基态组态的影响,也讨论了对称性变化的影响。     

(111)应变对立方相Ca2P0.25Si0.750.75能带结构及光学性质的影响

采用第一性原理贋势平面波方法对(111)应变下立方相Ca2P0.25Si0.75的能带结构及光学性质进行模拟计算,全面分析了应变对其能带结构、光学性质的影响。计算结果表明：在-8%~0%压应变范围内,随着应变的逐渐增大导带向低能方向移动,价带向高能方向移动,带隙逐渐减小,但始终为直接带隙;在0%~2%张应变范围内,随着应变的增加,带隙逐渐增大,应变为2%时直接带隙达到最大Eg=0.60441eV;当张应变为4%时,Ca2P0.25Si0.75变为间接带隙半导体。Ca2P0.25Si0.75的介电常数和折射率随着张应变的增加而增加;施加-2%~0%压应变时,介电常数和折射率逐渐减小,到达-2%时达到最小值,此后随着压应变的增加介电常数和折射率逐渐增大。施加压应变时吸收谱和反射谱随着应变的增大而减小,施加张应变时吸收谱和反射谱随着应变的增大而增大。应变可以改变立方相Ca2P0.25Si0.75的电子结构和光学常数,是调节其光电传输性能的有效手段。     

Au(111)表面Dy@C82分子单层膜的STM研究

利用超高真空扫描隧道显微镜(UHV-STM),在低温(78K)下研究了不同覆盖度下Dy@C82(Ⅰ)膜在Au(111)表面的生长和结构.Dy@C82分子首先吸附于金台阶,进而延伸至金台面上形成紧密排列的一维分子链或二维分子岛.高分辨STM图像显示ZDy@C82分子具有多种不同的内部结构,表明Dy@C82分子在金表面的取向是无序的.     

Electronic Structure of SiN Layers on Si(111) and SiC/Si(111) Substrates

Semiconductors - Ultrathin epitaxial silicon nitride films were formed on different Si(111) and SiC/Si(111) substrates by nitridation with plasma-activated nitrogen. Photoemission studies of the...     

0.7BiFeO_3-0.3PbTiO_3薄膜结构与电学性能的厚度效应

以溶胶–凝胶法在Pt/Ti/SiO2/Si(111)基底上制备了厚度为30~1 110 nm的0.7BiFeO3-0.3PbTiO3(0.7BFO-0.3PT)薄膜,研究了薄膜厚度对0.7BFO-0.3PT薄膜的结构与电学性能的影响。结果表明,随着膜厚的增加,晶格常数c与a的比值c/a以及晶粒尺寸都呈现先增大后减小的趋势,但其剩余极化强度及介电常数却均与薄膜厚度呈正比。厚度为180 nm的0.7BFO-0.3PT薄膜具有最大的矫顽场(2.99×105V/cm)和晶粒均匀度(42 nm),同时其晶格常数比c/a也达到最大,为1.129 9。     

On the profile of frequency dependent series resistance and surface states in Au/Bi4Ti3O12/SiO2/n-Si(MFIS) structures

The frequency dependent capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the metal-ferroelectric-insulator-semiconductor (Au/Bi₄Ti₃O₁₂/SiO₂/n-Si) structures (MFIS) were investigated by considering series resistance (R_s) and surface state effects in the frequency range of 1 kHz-5 MHz. The experimental C-V-f and G/ω-V-f characteristics of MFIS structures show fairly large frequency dispersion especially at low frequencies due to R_s and N_ss. In addition, the high frequency capacitance (C_m) and conductance (G_m/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real capacitance of MFIS structures. The R_s-V plots exhibit anomalous peaks between inversion and depletion regions at each frequency and peak positions shift towards positive bias with increasing frequency. The C⁻²-V plot gives a straight line in wide voltage region, indicating that interface states and inversion layer charge cannot follow the ac signal in the depletion region, but especially in the strong inversion and accumulation region. Also, it has been shown that the surface state density decreases exponentially with increasing frequency. The C-V-f and G/w-V-f characteristics confirm that the interface state density (N_ss) and series resistance (R_s) of the MFIS structures are important parameters that strongly influence the electrical properties of MFIS structures.     

Zn(SCN)_2·2H_2O晶体结构和喇曼光谱的研究

本文报道了一种新的非线性光学晶体Zn(SCN)_2·2H_2O的结构和喇曼光谱。对结构和喇曼光谱的关系进行了讨论。     

金纳米棒在Au(111)表面上的分散与STM表征

本文报道了金纳米棒的合成、在Au(111)表面上的分散、有机污染物清洗以及STM形貌表征工作.金纳米棒通过金晶种在金生长液中的选择性生长来制备.通过对金纳米棒和Au(111)表面进行修饰,利用涂层外端基团之间的静电相吸作用,把金纳米棒经由点滴法均匀地吸附在Au(111)表面上,且分散密度可通过点滴次数加以控制.本文进一...