电致发光显示究研动向

继粉末电致发光(注:以下电致发光均略写为EL)显示器件之后,1968年美国贝尔研究所研制出不同发光机理的高亮度薄膜EL器件,引起了广泛的注意。这种器件,是在ZnS中掺进希土类氟化物分子(TbF_3)作为发光中心,亮度达到数百尺朗伯(fL)。接着,美国Sigmatron公司又研制成硫化锌掺锰的三层薄膜EL器件,发光层背面镶有As_2S_3黑色绝缘层,提高了屏的反差。日本霞浦公司于1973年,研制成将ZnS发光层夹在Y_2O_3和Si_3N_4绝缘层间的对称型薄膜EL器件,亮度达1,500fL,     

Ⅱ-Ⅵ族化合物薄膜电致发光

电致发光薄膜是平板显示器的重要材料之一,我们从研究ZnS:Mn,Cu直流电致发光薄膜的大面积稳定发光开始,首次将稀土离子引进直流电致发光薄膜,实现了各色的直流电致发光,并研究其激发机理、过热电子的能量分布、稀土离子的碰撞截面和稀土离子发光中心在晶格中的位置等。在国内首先研制成功ZnS:Mn交流电致发光薄膜计算机终端显示器,并扩大面积到640×480像素(对角线10英寸)。为了实现彩色化显示,研制出稀土离子掺杂的各色交流电致发光薄膜。研究不同稀土离子在薄膜中的浓度猝灭,以便提高薄膜的发光亮度。在致力于实现彩色的过程中,首要的任务是提高蓝色电致发光薄膜的亮度和探索新的蓝色电致发光薄膜材料:从ZnS:TmF₃到CaS:TmF₃,发光亮度有了很大的提高;使SrS:Ce薄膜蓝色电致发光的亮度超过1000cd/m²;同时探索纳米Si和非晶Si/SiO₂超晶格结构的蓝色电致发光。成功地实现了ZnS:Mn/SrS:Ce白色电致发光和SrS:HoF₃三基色线谱发射的白色电致发光,发光亮度也超过1000cd/m²。     

《国外信息显示》一九七三年分类目录

一无机发光材料的一般问题: 发射光谱 余辉测量 光和颜色的测量 国外无机晶体发光研究概况 发光材料的能带结构 体效应场致发光 一种联合的发光中心 等电子陷阱二场致发光显示器件和材料: CdS:Cu粉末磷光体直流场致发光(DCEL)性质的研究 利用场致发光屏作发光天棚的可能性 粉末场致发光屏亮度的测量 粉末材料EL效率的测量 n一班族化合物粉末的直流场致发光 ZnS薄膜场致发光 粉末场致发光应用现状 薄膜PC一EL夹层型象加强器 碱卤晶体的场致发光简讯:一种硫化镐场致发光器件 ZnS:TbF3薄膜的直流场致发光 Mn注入的ZnS薄膜场致发光元件…     

ZnS作为空穴缓冲层的新型有机发光二极管

采用磁控溅射方法在ITO表面沉积了不同厚度的ZnS超薄膜作为有机发光二极管(OLEDs)的缓冲层,使典型结构(ITO/TPD/Alq3/Al)的OLEDs的发光性能得到改善。ZnS缓冲层厚度对器件性能影响的实验结果表明,当ZnS缓冲层厚度为5nm时,器件电流密度提高了近2倍,亮度提高了2倍;当ZnS缓冲层厚度为10nm时,器件发光的电流效率提高18%,器件的性能得到改善。宽禁带的ZnS缓冲层对空穴从阳极到有机功能层的注入有阻碍作用,促进器件载流子平衡,提高了器件发光效率,改善了器件性能。     

新结构电致发光薄膜器件各层的优化

本文比较了以SiO为预热层和以SiO2/Y2O3、SiO2/Ta2O5为复合预热层的新结构器件的发光亮度和传导电流,并拟合出这三种器件热电子能量,得出以SiO为预热层的新结构器件的热电子能量和发光亮度最高,比较了以SiO2和ZnS分别作加速层对发光和传导电荷的影响,得出在提高注入电荷方面,以ZnS做加速层优于SiO2做加速层；在提高热电子能量和发光亮度方面,以SiO2做加速层要好于ZnS做加速层。     

交流场致发光薄膜显示器

据美国《电气与电子工程师协会会报》1973年7期报导,美国西马闯公司制造的交流场致发光薄膜显示屏的结构如图所示。 场致发光薄膜材料主要是ZnS:Mn蒸发膜,膜的下面有一层黑色的电介质,上面有一层透明的电介质。黑色介电层的反射率仅为0.25％。在实验室正常照明条件下,反差比可达30:1。据称,当显示器表面亮度     

团聚效应对基于CdSe/ZnS量子点的电致发光二极管性能的影响

通过旋涂含有CdSe/ZnS量子点(Quantum dot,QD)的溶液为发光层薄膜,制备了叠层结构的电致发光二极管,利用原子力显微镜研究了QD发光亮度、薄膜形貌与其工艺条件、参数的关系。研究结果表明:随QD厚度的增加,QD纳米粒子薄膜由单层向多层薄膜形成,QD纳米颗粒发生团聚现象,并使器件亮度降低。此外,退火温度对QD薄膜形貌及其发光强度影响很大:当退火温度高于150 ℃时,产生的热量也会造成QD纳米粒子团聚,并导致QLED器件发光性能下降。     

退火处理对ZnS∶Cu,Mn电致发光材料亮度的影响

ZnS系列电致发光已经在低亮度照明、液晶显示、汽车和航空仪表等领域得到广泛的应用。Mn、Cu是ZnS电致发光材料常用的激活剂,Mn2+在晶体中形成橙色发光中心,发光中心波长580 nm;Cu+在晶体中不但形成发光中心,还形成发光所必需的CuxS,因此二者对发光亮度有明显的影响。由于ZnS∶Cu,Mn橙色发光材料中的Mn掺杂量较大,影响了发光材料的内在结构,在灼烧过程中Mn化合物的其他成分还可能对发光材料的亮度产生了不利的影响,导致发光材料的亮度远低于蓝绿色材料。采用在退火过程中添加适量的Mn、Cu化合物,通过低温扩散的方式,使Mn2+均匀进入到ZnS晶格,获得了亮度较高的ZnS∶Cu,Mn ACEL粉末材料。并对制备工艺中Cu、Mn含量、掺杂Mn化合物的形式、退火温度等对发光亮度的影响进行了讨论。实验中发现,在三种Mn化合物中(碳酸锰、乙酸锰、硫酸锰),以乙酸锰掺杂的材料亮度最高。得到Mn(以乙酸锰为添加物)的添加量为2%、Cu的添加量为0.1%、退火温度为700℃时,所制备的材料亮度最高。低温退火时掺杂Mn的材料亮度比常规材料的亮度高出1倍。     

退火处理对ZnS: Cu,Mn电致发光材料亮度的影响

ZnS系列电致发光已经在低亮度照明、液晶显示、汽车和航空仪表等领域得到广泛的应用.Mn、Cu是ZnS电致发光材料常用的激活剂,Mn²⁺在晶体中形成橙色发光中心,发光中心波长580nm;Cu⁺在晶体中不但形成发光中心,还形成发光所必需的Cu_xS,因此二者对发光亮度有明显的影响.由于ZnS:Cu,Mn橙色发光材料中的Mn掺杂量较大,影响了发光材料的内在结构,在灼烧过程中Mn化合物的其他成分还可能对发光材料的亮度产生了不利的影响,导致发光材料的亮度远低于蓝绿色材料.采用在退火过程中添加适量的Mn、Cu化合物,通过低温扩散的方式,使Mn²⁺均匀进入到ZnS晶格,获得了亮度较高的ZnS:Cu,MnACEL粉末材料.并对制备工艺中Cu、Mn含量、掺杂Mn化合物的形式、退火温度等对发光亮度的影响进行了讨论.实验中发现,在三种Mn化合物中(碳酸锰、乙酸锰、硫酸锰),以乙酸锰掺杂的材料亮度最高.得到Mn(以乙酸锰为添加物)的添加量为2%、Cu的添加量为0.1%、退火温度为700℃时,所制备的材料亮度最高.低温退火时掺杂Mn的材料亮度比常规材料的亮度高出1倍.     

场致发光ZnS:Er~(3 )薄膜的激发机理

在掺杂稀土离子的ZnS薄膜中,其发光中心为电场所激发的机理,过去认为可能有以下两种:(1)经由热电子直接碰撞激发;(2)基质晶格的碰撞离化产生了电子空穴对,继而发生从电子空穴对到发光中心的能量谐振迁移。 最近,Krupka证实了在ZnS:Tb~(3 )薄膜中的场致发光是由热电子直接碰撞而发生的。他观测了作为加在ZnS:Tb~(3 ),Ta_2O_5多层结构上的外加电压函数的荧光强度比     

Interface roughness: a reason of inaccessibility of the negative resistance region in resonant-tunneling devices

Interface roughness in double-barrier resonant-tunneling devices affects the lateral electron motion in the quantum well and can give rise to subsidiary subbands or quasibound states in the well. We demonstrate that a shoulder frequently appearing beyond the principal resonance peak in the current–voltage characteristic can result from the resonant tunneling via those states.     

AlGaN/GaN高电子迁移率晶体管肖特基高温退火机理研究

在不同应力条件下,研究了AlGaN/GaN高电子迁移率晶体管高温退火前后的电流崩塌、栅泄漏电流以及击穿电压的变化.结果表明,AlGaN/GaN高电子迁移率晶体管通过肖特基高温退火以后,器件的特性得到很大的改善.利用电镜扫描(SEM)和X射线光电子能谱(XPS)对高温退火前、后的肖特基接触界面进行深入分析,发现器件经过高温退火后,Ni和AlGaN层之间介质的去除,并且AlGaN材料表面附近的陷阱减少,使得肖特基有效势垒提高,从而提高器件的电学特性. 关键词： AlGaN/GaN高电子迁移率晶体管 肖特基接触 界面陷阱     

环绕声重放中通路信号相关性与听觉空间印象

通过心理声学实验研究了5.1通路环绕声重放中前方左、右,以及左环绕、右环绕四个扬声器通路信号相关性与听觉空间印象之间的关系。结果表明,对前方左、右扬声器重放或左环绕、右环绕扬声器重放,都可以通过控制通路信号的相关系数在一定程度上改变前方或后方声像的宽度。对不同频率范围的信号,声像宽度与通路信号的相关系数之间的定量关系有所不同。但对一对侧向扬声器重放,基本上不能通过控制通路信号相关系数来改变声像的宽度,并且声像宽度很窄。对于前方和环绕两对扬声器同时重放,对粉红噪声和中心频率不大于1 kHz的倍频程信号,适当控制各扬声器对通路信号的相关系数可以获得较强的包围感;但是对中心频率为2 kHz和4 kHz的倍频程信号则无法获得包围感。进一步的理论计算和实验测量结果表明,重放声像宽度和双耳听觉互相关系数(IACC)并没有唯一对应的关系,这可能和IACC的计算方法有关。对于IACC的计算方法和适用性还需要进一步的实验验证。本文的结果将有助于实际的环绕声节目制作和评价。      

Excited state biexcitons in monolayer WSe2 driven by vertically grown graphene nanosheets with high-density electron trapping edges

Interface engineering in atomically thin transition metal dichalcogenides (TMDs) is becoming an important and powerful technique to alter their properties, enabling new optoelectronic applications and quantum devices. Interface engineering in a monolayer WSe₂ sample via introduction of high-density edges of standing structured graphene nanosheets (GNs) is realized. A strong photoluminescence (PL) emission peak from intravalley and intervalley trions at about 750 nm is observed at the room temperature, which indicated the heavily p-type doping of the monolayer WSe₂/thin graphene nanosheet-embedded carbon (TGNEC) film heterostructure. We also successfully triggered the emission of biexcitons (excited state biexciton) in a monolayer WSe₂, via the electron trapping centers of edge quantum wells of a TGNEC film. The PL emission of a monolayer WSe₂/GNEC film is quenched by capturing the photoexcited electrons to reduce the electron-hole recombination rate. This study can be an important benchmark for the extensive understanding of light–matter interaction in TMDs, and their dynamics.     

对5通路3/2环绕声系统缺陷的分析

本文利用环绕声重发的声像定位理论，对一种受到重视、很可能将被国际上广泛应用的通用环绕声系统—5通路3／2系统的声像特性进行了分析，并对系统进行了声像定位实验．理论和实验结果表明，按目前的信号馈给方式，系统可在倾听者前方产生稳定而明晰的声像；但在侧向和后方只能产生模糊和不稳定的声像（扬声器方向除外）；将别是在侧向，存在着一个声像的死区，并且对侧向和后方声像来说，听音区域片不宽阔，因而作为一种通用的系统，虽然将其用作伴随图像的重发时，可获得较好的效果；但用作不伴随图像的重发时，系统并不能很好地再观原声场的空间感。由于系统存在这种不容忽视的缺陷，文中着重强调应设法在这方面对系统加以改进     

Evidence for different types of mechanoreceptors from measurements of the psychophysical threshold for vibrations under different stimulation conditions

The shape of the psychophysical frequency threshold curve for vibrations presented to the skin in the frequency region 5-1000 Hz is strongly dependent on the static force that the vibrator exerts on the skin and on whether there is a rigid surround around the vibrating contactor (presence of contrast). Where there is no rigid surround, an increase in static force reduces the threshold in the high-frequency region and increases it at low frequencies. When the static forces are sufficiently large, the thresholds reach a minimum value above 30 Hz and a maximum one below 30 Hz, this being the crossover frequency. Under these conditions in the frequency region around 200 Hz, where the threshold is determined by the Pacini receptor system, the vibration sensitivities of finger pad and thenar eminence (glabrous skin) are equal, while the value for the inner side of the forearm (hairy skin) is 12 dB higher. However, when a rigid surround is used, the threshold increases above 30 Hz and decreases below 30 Hz. The latter increase in sensitivity, which is introduced by the presence of contrast cues, amounts to about 20 dB and is sharply tuned at 18 Hz for the glabrous skin of the finger. It is argued that in this case the threshold is determined by the Meissner receptor system. This increase in sensitivity is less pronounced (about 10 dB) and less sharply tuned for the other sites. Finally, when the contact of the vibrating surface to the skin is at a minimum, the vibration threshold has the same displacement value (about 3 microns) over the whole frequency region independent of the site of stimulation and whether or not a rigid surround is present.     

改进的5.1通路环绕声三扬声器虚拟重发系统

提出一种改进的5．1通路环绕声的三扬声器虚拟重发系统。本文首先指出,现有的两扬声器虚拟重发存在听音区域窄、声像稳定性差等缺陷。通过理论分析和心理声实验证明,采用一对布置在前方±30°的全频带扬声器和一个前方0°的高频中置扬声器组成5．1通路环绕声虚拟重发系统,不但可提高重发声像的稳定性,且扬声器布置实际可行,信号处理相对简单。因此所提出的虚拟系统及其扬声器布置是适合于电视和多媒体计算机的应用。     

The effects of a surround on vibrotactile thresholds: evidence for spatial and temporal independence in the non-Pacinian I (NPI) channel

Detection thresholds were measured for sinusoidal vibrations applied to the thenar eminence and volar forearm. Stimuli were applied via a 0.72-cm2 circular contactor, with and without a rigid surround. At low frequencies, below about 40 Hz, the thresholds were higher without the surround than with the surround. However, in contrast to earlier reports, the shape of the threshold function was the same with and without the surround, suggesting that the temporal and spatial tuning characteristics of the non-Pacinian I (NPI) channel are independent.     

Interface models and processing technologies for surface passivation and interface control in III-V semiconductor nanoelectronics

Interface models and processing technologies are reviewed for successful establishment of surface passivation, interface control and MIS gate stack formation in III-V nanoelectronics. First, basic considerations on successful surface passivation and interface control are given, including review of interface models for the band alignment at interfaces, and effects of interface states in nanoscale devices. Then, a brief review is given on currently available surface passivation technologies for III-V materials, including the Si interface control layer (ICL)-based passivation scheme by the authors’ group. The Si-ICL technique has been successfully applied to surface passivation of nanowires and to formation of a HfO₂ high-k dielectric/GaAs interfaces with low values of the interface state density.     

Comparison between post-irradiation annealing and post-high electric field stress annealing of n-channel power VDMOSFETs

The behavior of the defects created in the gate oxide and at the Si/SiO₂ interface of n-channel power vertical double-diffused metal-oxide-semiconductor field-effect transistors (VDMOSFETs) by irradiation and positive high electric field stress have been investigated. Interface traps exhibit the same behavior after both types of stress, while there are significant differences in post-stress responses of the charge trapped in the oxide, consisting of fixed and switching component.