PTCDA/P-Si光电探测器欧姆接触层的XPS测试分析

在光电探测器PTCDA/P-Si芯片的有机层表面,成功制作出了比接触电阻为4.5×10-5Ω·cm2的低阻欧姆接触层。利用X射线光电子能谱(XPS)对Al/Ni/ITO的欧姆接触层界面的电子状态进行了测试和分析。结果表明,ITO中的In3d及Sn3d各出现两个分裂能级的谱峰,它们是In和Sn原子处于氧化环境的结合能。Ni2p有两个谱峰Ni2p(1)及Ni2p(2),低结合能位置Ni2p(1)对应于Ni原子被X射线激发产生的谱峰,说明NiITO之间没有发生化学反应,Ni层阻止了Al层被氧化成Al2O3;高结合能Ni2p(2)谱峰说明已形成了Al3Ni冶金相,有利于低阻欧姆接触层的形成。     

一种新型平板彩色显示器件的制备和光谱分析

以MEH-PPV(聚[2-甲氧基-5-(2'-乙基己氧基-对苯乙烯)])和Alq3作为发光层,成功制备出ITO/SiO2/MEH-PPV/SiO2/Al结构和ITO/SiO2/Alq3/SiO2/Al结构的固态阴极射线器件.通过分析SSCL光谱,认为这些高速电子激发有机材料后形成Frenkel激子.当器件两个电极之间加的电压比较低时,有机薄膜层的场强也比较低,这些激子被解离的概率很小,从而产生的是激子发光的长波发射;当器件两个电极之间加的电压比较高时,有机薄膜层的场强很高,在有机层形成的激子大部分被解离,解离后的电子直接跃迁至LUMO(lowest unoccupancied molecular orbit),这些电子弛豫后从LUMO能级到HOMO(highest occupancied molecular orbit)能级直接辐射跃迁,接着重新复合发光,从而产生短波发射.制作的固态阴极射线器件可以实现全色发光,提高发光效率和加强蓝光发射.作者可以预期所研制出的这种SSCL器件必将引发平板显示领域一场新的革命性变革.     

Numerical investigations on the current conduction in bilayer organic light—emitting devices with ohmic injection of charge carriers

A numerical model for bilayer organic light-emitting diodes (OLEDs) has been developed on the basis of trappedcharge limited conduction. The dependences of the current density on the operation voltage, the thickness andtrap properties of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure an-ode/HTL/EML/cathode have been numerically investigated. It has been found that, for given values of reduced trapdepth, total trap density, and carrier mobility of HTL and EML, there exists an optimum thickness ratio of HTL tothe sum of HTL and EML, by which a maximal current density, and hence maximal quantum efficiency and luminance,can be achieved. The current density decreases quickly with the mean trap density, and decreases nearly exponentiallywith the mean reduced trap depth.     

Deposition of carbon nitride films for space application

Carbon nitride thin films were prepared by electron-beam evaporation assisted with nitrogen ion bombardment and TiN/CN_x composite films were by unbalanced dc magnetron sputtering, respectively. It was found that the sputtered films were better than the evaporated films in hardness and adhesion. The experiments of atomic oxygen action, cold welding, friction and wearing were emphasized, and the results proved that the sputtered TiN/CN_x composite films were suitable for space application.     

蓝色有机发光材料LiBq4的合成及其发光特性

蓝色有机发光材料的开发对于实现有机发光二极管(OLED)的全彩色化具有十分重要的意义.报道了蓝色有机发光材料8-羟基喹啉硼化锂(LiBq₄)的合成及提纯,研究了LiBq₄的光致发光特性,并用LiBq₄作为发光材料制备了蓝色有机发光器件,研究了电子传输层Alq₃的厚度及空穴缓冲层CuPc对器件电流-电压和亮度-电压特性的影响.结果表明,LiBq₄的光致发光峰值波长为452nm,器件ITO/PVK:TPD/LiBq₄/Alq₃/Al的电致发光光谱峰值波长位于475nm处,在25V工作电压下其最高亮度约为430cd/m².但CuPc的加入加剧了器件中载流子的不平衡注入,导致器件性能恶化.通过调整Alq₃的厚度,同时在Alq₃和Al阴极之间加入LiF薄膜以提高电子注入效率,获得了较为理想的实验结果.     

Air-stable ambipolar organic field effect transistors with heterojunction of pentacene and N,N''-bis(4-trifluoromethylben-zyl)perylene-3,4,9,10-tetracarboxylic diimide

Fabrication of ambipolar organic field-effect transistors(OFETs) is essential for the achievement of an organic complementary logic circuit.Ambipolar transports in OFETs with heterojunction structures are realized.We select pentacene as a P-type material and N,N’-bis(4-trifluoromethylben-zyl)perylene-3,4,9,10-tetracarboxylic diimide(PTCDI-TFB) as a n-type material in the active layer of the OFETs.The field-effect transistor shows highly airstable ambipolar characteristics with a field-effect hole mobility of 0.18 cm 2 /(V·s) and field-effect electron mobility of 0.031 cm 2 /(V·s).Furthermore the mobility only slightly decreases after being exposed to air and remains stable even for exposure to air for more than 60 days.The high electron affinity of PTCDI-TFB and the octadecyltrichlorosilane(OTS) self-assembly monolayer between the SiO 2 gate dielectric and the organic active layer result in the observed air-stable characteristics of OFETs with high mobility.The results demonstrate that using the OTS as a modified gate insulator layer and using high electron affinity semiconductor materials are two effective methods to fabricate OFETs with air-stable characteristics and high mobility.     

Alq3/ITO结构的表面和界面电子状态的XPS研究

用传统的真空蒸镀法制备了Alq3/ITO样品,并用X光电子能谱（XPS）研究了Alq3/ITO紧密接触的表面和界面电子化学状态。对Alq3/ITO样品的表面分析表明,在Alq3分子中,Al原子的束缚能（Eb)为70．7eV和75．1eV,分别对应于Al(0)和Al(Ⅲ）态;C原子的束缚能为285．8eV、286．3eV和286．8eV,分别对应于C－C、C－O和C－N键;N原子的主峰位于401．0eV,对应于C－N＝C键;而O原子主要与H原子成键,其束缚能为532．8eV。为了研究Alq3/ITO的界面电子状态,我们用氩离子束对样品表面进行了溅射剥蚀,当溅射时间分别为30,35,45分种时进行XPS采谱分析。结果表明,随着氩离子束溅射时间增长,Al2p、Cls、Nls、Ols、In3d5/2和Sn3d5/2峰都向低束缚能方向有微小移动,且Al2p、Cls和Nls峰变弱,这是受ITO中扩散进入Alq3层的O、In和Sn原子的影响所致。     

用AFM和XPS研究LiBq4/ITO的表面和界面

用原子力显微镜(AFM)研究了LiBq4／ITO样品表面形貌,结果表明LiBq4层中存在很多裂缝和空隙。用X射线光电子谱(XPS)研究样品表面和界面的电子状态,发现Cls谱在高结合能端出现氧化特征的肩峰,表明真空蒸发沉积的LiBq4分子存在明显的氧化现象;对Bls谱的分析发现,界面处B原子的相对值远低于理论值,说明界面处存在B原子离解,导致了LiBq4分子的更高氧化态;从Cls谱发现,表面污染C的比例很高,而界面处大为下降,原因是表面吸附了气体,从而证实了LiBq4表面存在大量空隙和裂缝。定量研究发现,界面处存在N原子与In、Sn原子的相互作用,这将影响LiBq4的发光颜色。     

PTCDA/ITO表面和界面的X射线光电子能谱分析

利用X射线光电子能谱对PTCDA/p-Si有机/无机光电探测器中PTCDA/ITO表面和界面进行了测试分析. 结果表明, 苝环上的C原子的结合能为284.6 eV, 酸酐中的C原子的结合能为288.7 eV, 并存在来源于ITO膜中的氧对C原子的氧化现象, 界面处C(1s)谱中较高结合能峰消失, 且峰值向低结合能发生化学位移;CO键中O原子的结合能为531.5 eV, C-O-C键中的O原子的结合能为533.4 eV.     

窄禁带稀磁半导体二维电子气的拍频振荡

通过对调制掺杂的n型Hg_0.82Cd_0.16Mn_0.02Te/Hg_0.3Cd_0.7Te第一类量子阱中磁性二维电子气磁阻拍频振荡的研究，发现温度、栅压的变化都会引起磁阻拍频节点位置的变化.从对拍频的分析中，可以将依赖于栅压的Rashba自旋-轨道分裂和依赖于温度的巨大塞曼分裂区分开来. 关键词： 磁性二维电子气 自旋分裂 sp-d交换相互作用 拍频