Fe/ZnO(0001)界面的同步辐射光电子能谱研究

利用同步辐射光电子能谱研究了Fe/ZnO生长模式、界面化学反应和电子结构.结果表明，Fe在ZnO(0001)表面以类SK模式生长(单层加岛状生长).当沉积约2?的Fe后，生长模式开始从二维层状生长转变成混合模式生长.界面价带谱和Fe3p芯能级谱的分析表明，在低覆盖度下，约有一个原子层(约1.5?)的Fe被ZnO(0001)面的外层O原子氧化，随着沉积厚度的增加，金属态Fe的信号逐渐增强.当吸附了5.1?的Fe时，出现了较强的金属Fe的Fermi边，说明出现了Fe的金属态.此外，在Fe原子吸附过程中，样品功函数在Fe厚度为0.2?时达到最小值4.5eV，偶极层形成后逐渐稳定在4.9eV.     

Fe/ZnO(0001-)界面的同步辐射光电子能谱研究

利用同步辐射光电子能谱研究了Fe／ZnO生长模式、界面化学反应和电子结构．结果表明，Fe在ZnO（0001^-）表面以类SK模式生长（单层加岛状生长）．当沉积约2A的Fe后，生长模式开始从二维层状生长转变成混合模式生长．界面价带谱和Fe3p芯能级谱的分析表明，在低覆盖度下，约有一个原子层（约1．5A）的Fe被ZnO（0001）面的外层0原子氧化，随着沉积厚度的增加，金属态Fe的信号逐渐增强．当吸附了5．1A的Fe时，出现了较强的金属Fe的Fermi边，说明出现了Fe的金属态．此外，在Fe原子吸附过程中，样品功函数在Fe厚度为0．2A时达到最小值4．5．eV，偶极层形成后逐渐稳定在4．9eV．     

Fe/ZnO (0001)体系界面相互作用中薄膜厚度效应的光电子能谱研究

利用同步辐射光电子能谱(SRPES)和X射线光电子能谱(XPS)技术,系统研究了室温下Fe/ZnO界面形成过程中Fe薄膜与氧结尾的ZnO(000 1 )衬底之间的相互作用,结果显示初始沉积的Fe明显被表面氧氧化为Fe²⁺离子,在Fe覆盖度为0—3 nm的范围内,分别观察到与界面电荷传输、化学反应以及薄膜磁性相关的三个有意义的临界厚度,这一结果将有助于基于Fe/ZnO界面的相关器件的设计和研发. 关键词： Fe/ZnO 界面作用 同步辐射光电子能谱 X射线光电子能谱     

Ge/ZnSe(100)异质结能带偏移的同步辐射光电子能谱研究

利用同步辐射光电子能谱研究了Ge/ZnSe（100）极性界面的能带连接问题．表面灵敏的芯能级谱显示出Ge原子与Se原子在界面处存在较弱的化学反应．利用芯能级技术，测量了该异质结的价带偏移，为1.76±0.1eV．用界面键极性模型对ZnSe（100）极性表面对价带偏移的影响进行了讨论，理论与实验符合较好 关键词：     

室温下InP(100)表面K诱发催化氮化反应的同步辐射光电子能谱研究

利用同步辐射光电子能谱研究了室温下p型InP(100)表面,由于K吸附诱发的催化氮化反应过程。对于N_2/K/InP(100)体系的P2p;In4d芯能级和价带谱的研究表明:碱金属吸附于InP(100)表面可以强烈地影响其在室温下的氮化反应,K的存在极大地提高了N_2在InP(100)表面的粘附系数。由我们的实验结果和碱金属吸附于GaAs(110),InP(110),GaP(110)表面的研究结果可知,碱金属吸附于Ⅲ-V族半导体表面后,可以极大地提高N_2在Ⅲ-V族半导体表面的粘附系数,从而促进Ⅲ-V族半 关键词：     

Ni/Au与N掺杂p型ZnO的欧姆接触

研究了Au,In,Ni/Au三种不同金属膜与N掺杂p型ZnO的接触特性,发现Ni/Au双层膜更适合作为其欧姆电极材料,并比较了不同气氛和不同温度退火对Ni/Au电极的影响.发现在O₂中退火电极性能发生蜕变,而在N₂中退火性能得到改善.指出即使在N₂中退火,退火温度的选择也是至关重要的,本实验在400℃,氮气气氛下退火150s,得到了较好的欧姆接触特性.     

Fe/ZnO (0001)体系界面相互作用中薄膜厚度效应的光电子能谱研究

利用同步辐射光电子能谱(SRPES)和X射线光电子能谱(XPS)技术,系统研究了室温下Fe/ZnO界面形成过程中Fe薄膜与氧结尾的ZnO(000 1 )衬底之间的相互作用,结果显示初始沉积的Fe明显被表面氧氧化为Fe²⁺离子,在Fe覆盖度为0—3 nm的范围内,分别观察到与界面电荷传输、化学反应以及薄膜磁性相关的三个有意义的临界厚度,这一结果将有助于基于Fe/ZnO界面的相关器件的设计和研发.     

氧气氛中p-GaN/Ni/Au电极在相同温度不同合金时间下的欧姆接触形成机制和扩散行为

用卢瑟福背散射/沟道技术研究了p-GaN上的Ni/Au电极在氧气氛下相同合金温度(500℃)不同合金时间后的微结构演化,以揭示欧姆接触的形成机制.利用背散射随机谱和RUMP模拟程序研究了电极金属之间的互扩散,用沟道谱探测了电极金属中的氧分布.结合不同合金时间下比接触电阻ρ_c的变化,发现随着合金时间的延长比接触电阻持续降低,在合金时间60 s后降低的速度减慢, Au扩散到GaN的表面,在p-GaN上形成外延结构,O向电极内部扩散反应生成NiO对降低ρ_{关键词： GaN 卢瑟福背散射/沟道 欧姆接触}     

AlGaN/GaN异质结Ni/Au肖特基表面处理及退火研究

采用O₂等离子体及HF溶液对AlGaN/GaN异质结材料进行表面处理后，Ni/Au肖特基接触特性比未处理有了明显改善，反向泄漏电流减小3个数量级.对制备的肖特基接触进行200—600℃ 5min的N₂气氛退火，发现退火冷却后肖特基反向泄漏电流随退火温度增大进一步减小.N₂气中600℃退火后肖特基二极管C-V特性曲线在不同频率下一致性变好，这表明退火中Ni向材料表面扩散减小了表面陷阱密度；C-V特性曲线随退火温度增大向右移动，从二维电子气耗尽电压绝对值减小反映了肖特基势垒的提高. 关键词： AlGaN/GaN 肖特基接触 表面处理 退火     

Initial interface study of Au deposition on GaN(0 0 0 1)

Synchrotron radiation photoelectron spectroscopy (SRPES) has been used to study the electronic structure of the Au/GaN(0 0 0 1) system at the initial growth stage. The peak fitting of Au4f_7/2 core-level and the energy shift of valence band indicate that Au–Ga alloy were formed in the interface reaction. According to the Ga3d signal intensity attenuation vs. the gold film thickness, the early growth mode is considered to be 3D mode above the reaction layer. By using the Linear Augmented Plane Wave method the density of states (DOS) for GaN and Au bulk are calculated within the framework of local functional theory. The theoretical results agree with the valence band structure quite well. The mechanism of interface reaction is discussed based on the experimental and theoretical results.     

Synchrotron radiation photoemission study of interface formation between MgO and the atomically clean In0.53Ga0.47As surface

The evolution of interface formation between MgO and the atomically clean In_0.53Ga_0.47As is studied by synchrotron radiation based photoemission. The deposition of MgO in a step wise fashion on the decapped In_0.53Ga_0.47As surface at room temperature results in the growth of an ultrathin interfacial oxide layer. Subsequent thermal annealing at 400 °C led to the reduction of the As and In oxides and the appearance of a Ga oxide component. The deposition of metallic Mg resulted in the further removal of the interfacial oxide and the out diffusion of In into the overlayer indicating severe disruption of the interface. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Energy band alignment of PbTe/CdTe(111) interface determined by ultraviolet photoelectron spectra using synchrotron radiation

The energy band structure with type-I alignment at the PbTe/CdTe(111) heterojunction interface is determined by the ultraviolet photoelectron spectrum using synchrotron radiation.The valence band and conduction band offsets are obtained to be 0.09±0.12 and 1.19±0.12 eV,respectively.These results are in agreement with theoretically predicted ones.The accurate determination of the valence band and conduction band offsets is useful for the fundamental understanding of the mid-infrared light emission from the PbTe/CdTe heterostructures and its application in devices.     

利用同步辐射光电子能谱技术测量ZnO/PbTe异质结的能带带阶

异质结结构界面的能带带阶是一个非常重要的参数,该参数的精确确定直接影响异质结的光电性质研究以及异质结在光电器件上的应用.利用同步辐射光电子能谱技术测量了ZnO/PbTe异质结结构的能带带阶.测量得到该异质结价带带阶为2.56 eV,导带带阶为0.49 eV,是一个典型的类型I的能带排列.利用变厚度扫描的测量方法发现,ZnO/PbTe界面存在两种键,分别是Pb—O键(低结合能)和Pb—Te键(高结合能).在ZnO/PbTe异质结界面的能带排列中导带带阶较小,而价带带阶较大,这一能带结构有利于PbTe中的激发电子输运到ZnO导电层中.该类结构在新型太阳电池、中红外探测器、激光器等器件中具有潜在的应用价值.     

Comparative study of adsorption characteristics of Cs on the GaN （0001） and GaN （0001） surfaces

The adsorption characteristics of Cs on GaN （0001） and GaN （0001） surfaces with a coverage from 1/4 to 1 monolayer have been investigated using the density functional theory with a plane-wave uttrasoft pseudopotential method based on first-principles calculations. The results show that the most stable position of the Cs adatom on the GaN （0001） surface is at the N-bridge site for 1/4 monolayer coverage. As the coverage of Cs atoms at the N-bridge site is increased, the adsorption energy reduces. As the Cs atoms achieve saturation, the adsorption is no longer stable when the coverage is 3/4 monolayer. The work function achieves its minimum value when the Cs adatom coverage is 2/4 monolayer, and then rises with Cs atomic coverage. The most stable position of Cs adatoms on the GaN （000i） surface is at H3 site for 1/4 monolayer coverage. As the Cs atomic coverage at H3 site is increased, the adsorption energy reduces, and the adsorption is still stable when the Cs adatom coverage is 1 monolayer. The work function reduces persistently, and does not rise with the increase of Cs coverage.     

Resonant photoemission study of Ti interaction with GaN surface

Ti/GaN interface formation on GaN(0 0 0 1)-(1 × 1) surface has been investigated by means of resonant photoelectron spectroscopy (for photon energies near to Ti 3p → 3d excitation). The sets of photoelectron energy distribution curves were recorded for in situ prepared clean GaN surface and as a function of Ti coverage followed by post-deposition annealing. Manifestations of chemical reactions at the Ti/GaN interface were revealed in the valence band spectra as well as in the Ga 3d core level peak—the discerned contribution of Ti 3d states to the valence band turned out to be similar to that reported in the literature for titanium nitride. The interaction between Ti and N was further enhanced by post-deposition annealing. The study was complemented with SIMS and AFM measurements.     

苝四甲酸二酐在Au(111)表面的取向生长及电子结构研究

利用X射线光电子能谱(XPS),同步辐射紫外光电子能谱(SRUPS),近边X射线吸收精细结构(NEXAFS)以及原子力显微镜(AFM)等技术研究了苝四甲酸二酐(PTCDA)与Au(111)的界面电子结构、PTCDA分子取向及有机薄膜的表面形貌.SRUPS价带谱显示,伴随PTCDA分子的微量沉积(0·5ML),位于费米能级附近Au的表面电子态迅速消失,但却观察不到明显的界面杂化态,这说明PTCDA分子和Au(111)界面间存在弱电子传输过程,但并没有发生明显的化学反应.角分辨NEXAFS以及SRUPS结果证明PTCDA分子是平铺在衬底表面.根据Au4f7/2和C1s峰积分强度随薄膜厚度的变化以及AFM图像可知,PTCDA分子在Au(111)表面是一种典型的Stranski-Krastanov生长模式,即先层状生长,再岛状生长,并且在层状生长到岛状生长的转变过程中,存在有机分子的去润湿过程.