超薄氧化铝层的电场调制效应（英文）

研究了基于高k介质材料的阻变存储器的写入/擦除(SET/RESET)特性和物理机制.研究发现基于NbAlO材料的阻变存储器SET/RESET电压具有较大波动性,通过结构优化,在Al_2O_3/NbAlO/Al_2O_3纳米薄片堆垛结构器件中获得高度稳定性的可重复的阻变特性.基于电场调制效应,提出了一种统一的电阻开关模型去模拟阻变存储器的SET/RESET行为,并探讨了单层阻变薄膜的阻变存储器中由导电单元形成和湮灭的巨大随机性引起的阻变特性分布.当在NbAlO基阻变存储器中嵌入超薄Al_2O_3膜后,阻变存储器的SET/RESET电压稳定性将显著提升,其原因在于采用堆垛结构的阻变器件中各介质层中的电场重新分布并精确可控,因此导电细丝的导通/断裂通过电场调制作用稳定均匀地在发生在具有高电场的薄缓冲层介质层中.     

厚度与带隙可调、原子层沉积的超薄五氧化二钒纳米晶薄膜

利用原子层沉积方法制备V_2O_5纳米片晶薄膜.薄膜厚度可以被精确控制,并对纳米晶V_2O_5薄膜的结构形貌、光学带隙和拉曼振动有显著影响.原子层沉积过程中V_2O_5薄膜生长的两个阶段导致薄膜具有两个光学带隙,这将有助于理解超薄薄膜生长与功能应用.     

原子层沉积技术发展现状

复杂的非平面结构基板形貌对传统的薄膜沉积技术产生了极大的挑战,不同类型的集成电路器件需要不同的生产技术,同时也对薄膜材料提出了不同的要求。为了突破现有材料的性能限制就要求开发具有更高性能的材料。原子层沉积(ALD)是一种可足以应对这些挑战的独特技术,它所沉积的薄膜具有极佳的均匀性、台阶覆盖率和(对薄膜图形的)保形性。介绍了原子层沉积技术原理、新一代逻辑组件所面临的课题、原子气相沉积技术AVD及原子层沉积设备现状。     

复合介质层SOI高压器件电场分布解析模型

提出复合介质埋层SOI(compound dielectric buried layer SOI,CDL SOI)高压器件新结构,建立其电场和电势分布的二维解析模型,给出CDL SOI和均匀介质埋层SOI器件的RESURF条件统一判据.CDL SOI结构利用漏端低k(介电常数)介质增强埋层纵向电场,具有不同k值的复合介质埋层调制漂移区电场,二者均使耐压提高.借助解析模型和二维数值仿真对其电场和电势进行分析,二者吻合较好.结果表明,对低k值为2的CDL SOILDMOS,其埋层电场和器件耐压分别比常规SOI结构提高了82%和58%.     

有n缓冲层SOI RESURF结构的电场分布解析模型

提出了有n缓冲层SOI RESURF结构的电场分布解析模型,采用MEDICI数值仿真,验证了上述模型的正确性。基于所建立的解析模型,获得了缓冲层的最优杂质浓度分布,提出了提高SOI RESURF结构耐压的缓冲层分段变掺杂新结构。     

铁电薄膜和铁电场效应存储器研究

简述了铁电场效应管ＦＦＥＴ工作原理；说明了器件对薄膜和结构的要求；指出了铁电薄膜的电滞回线及金属铁电半导体结构的Ｃ－Ｖ特性。     

电光晶体中电场分布对相位调制的影响

用有限差分法计算了不同电极宽度下,电光晶体(LiNbO3)内部的电场分布情况,详细分析了电场不均匀性对晶体折射率和光束相位延迟的影响规律.发现选择合适的电极宽度,充分利用晶体中轴附近相对均匀的电场分布,可以避开复杂的边缘效应,同时能够降低畸变率,从而提高调制的精确性和稳定性.     

一种电场调制载流子存储槽栅双极型晶体管

提出了一种性能优良的电场调制载流子存储槽栅双极型晶体管(CSTBT)。结合电场调制原理,在器件的载流子存储(CS)层引入P掺杂条,改善器件栅极下方氧化硅拐角处的电场分布,防止器件提前发生雪崩击穿,提高了器件的击穿电压。器件处于关断状态时,内部大量的空穴载流子通过CS层中未完全耗尽的P掺杂条到达发射极,抑制了CS层阻挡空穴的作用,有效提高了器件的关断速度。与传统CSTBT器件相比,改进器件的击穿电压值提高了379 V,关断时间缩短了19.1%,器件性能大幅提高。     

硫化锌薄膜的原子层沉积生长及表征

为满足硫化锌(ZnS)薄膜在光学薄膜领域进一步应用的要求,基于原子层沉积(Atomic Layer Deposition, ALD)技术在130℃温度下以二乙基锌(DEZ)和硫化氢(H2S)为反应源,在砷化镓(GaAs)衬底表面沉积了ZnS薄膜。用扫描电子显微镜(Scanning Electron Microscope, SEM)分析了样品的表面形貌和膜界面特性,用X射线衍射仪(X-ray Diffraction, XRD)分析了薄膜的结构特性,并通过X射线光电子能谱(X-ray Photoelectron Spectroscopy, XPS)分析了薄膜的化学成分。研究了厚度对薄膜结构和形貌的影响。结果表明,得到的ZnS薄膜为多晶结构,薄膜的厚度随循环数线性增加,速率为1.45 ?/cycle。对在75℃温度下烘烤48 h后的薄膜进行了XPS分析,得出的Zn/S比为1.07:1,表明烘烤除去了薄膜中残存的H2S。以较短生长时间得到的较薄的薄膜具有更好的表面平整度和更致密的结构。     

Giant modulation of magnetism in(Ga,Mn)As ultrathin films via electric field

Taking the advantages of semiconducting properties and carrier-mediated ferromagnetism in(Ga,Mn)As,a giant modulation of magnetism via electric field in(Ga,Mn)As ultrathin film has been demonstrated.Specifically,huge interfacial electric field is obtained by using ionic liquid as the gate dielectric.Both magnetization and transport measurements are employed to characterize the samples,while the transport data are used to analyze the electric filed effect on magnetism.Complete demagnetization of(Ga,Mn)As film is then realized by thinning its thickness down to ~2 nm,during which the degradation of ferromagnetism of(Ga,Mn)As ultrathin film induced by quantum confinement effect is suppressed by inserting a heavily-doped p-type GaAs buffer layer.The variation of the Curie temperature is more than 100 K,which is nearly 5-times larger than previous results.Our results provide a new pathway on the efficient electrical control of magnetism.     

Effect of the radial electric field on absorption in a quantized spherical layer

Electronic states in the quantized spherical layer under the presence of a static radial field are considered. Expressions for the energy spectrum and the wave functions of carriers are obtained. The electroabsorption coefficient has a resonance nature; electric-field induced oscillations are observed in each subband. The external field leads also to a shift of the absorption edge to shorter wavelengths. A weak rise of the absorption coefficient is observed in each quantum-well subband with increasing field.     

工频电场对ADSS光缆特性的影响

随着电压等级的不断提高,超高压输电线路发展非常迅速.但是这些架空输电线路在运行时,附近存在较高的电场,对周围物体和公用走廊的其它线路会产生影响.电压等级越高,产生的电场影响越大.输电线路产生的电场越来越受到人们的重视.尤其是对于超高压输电线路,由于在电力铁塔上同塔悬挂全介质自承式光缆(ADSS),因此分析工频电场对ADSS光缆特性的影响非常必要.     

Model for modulation doped field effect transistor

A model describingC-VandI-Vcharacteristics of modulation doped FET's is proposed. The model takes into account the change in the Fermi energy with the gate voltage. At high two dimensional electron concentrations, the equations of the model for the charge control by the gate voltage become similar to the equations of the charge control model where the thickness d of AlGaAs layer should be substituted by d + Δ d and Δ d is the effective width of the potential well (≃ 80 Å). Another important prediction of the model is the existence of the "subthreshold" current. A very good quantitative agreement is obtained with our experimentalI-Vcurves using the measured values of the low field mobility and the source resistance.     

Effect of BCP ultrathin layer on the performance of organic light-emitting devices

Based on conventional double layer device, triple layer organic light-emitting diodes （OLEDs） with two heterostructures of indium-tin oxide （ITO）/N,N＇-diphenyl-N,N＇-bis（1-naphthyl）（1,1 ＇-biphenyl）-4,4＇-diamine（NPB）/2,9-dimethyl-4,7-diphenyl- 1,10-phenanthroline （BCP）/8-Hydroxyquinoline aluminum （Alq3）/Mg：Ag USing vacuum deposition method have been fabricated. The influence of different film thickness of BCP layer on the performance of OLEDs has been investigated. The results showed that when the thickness of the BCP layer film gradually varied from 0.1 nm to 4.0 nm, the electroluminescence （EL） spectra of the OLEDs shifted from green to greenish-blue to blue, and the BCP layer acted as the recombination region of charge carriers related to EL spectrum, enhancing the brightness and power efficiency. The power efficiency of OLEDs reached as high as 7.3 lm/W.     

The effect of external electric field on the performance of perovskite solar cells

Planar heterojunction perovskite solar cells were fabricated through a low temperature approach. We find that the device performance significantly depends on the external bias before and during measurements. By appropriate optimization of the bias conditions, we could achieve an 8-fold increase in the power conversion efficiency. The significant improvement in device performance might be caused by the ion motion in the perovskite under the external electric field.     

Effect of BCP ultrathin layer on the performance of organic light-emitting devices

Based on conventional double layer device, triple layer organic light-emitting diodes (OLEDs) with two heterostructures of indium-tin oxide (ITO)/N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'-diamine(NPB)/2,9-dimethyl-4,7-diphenyl- 1,10-phenanthroline (BCP)/ 8-Hydroxyquinoline aluminum (Alq3)/Mg:Ag using vacuum deposition method have been fabricated. The influence of different film thickness of BCP layer on the performance of OLEDs has been investigated. The results showed that when the thickness of the BCP layer film gradually varied from 0.1 nm to 4.0 nm, the electrolumines- cence (EL) spectra of the OLEDs shifted from green to greenish-blue to blue, and the BCP layer acted as the recombination region of charge carriers related to EL spectrum, enhancing the brightness and power efficiency. The power efficiency of OLEDs reached as high as 7.3 lm/W.     

CBP超薄层对有机电致磷光器件效率的影响

在空穴传输层(HTL)和发光层(EML)间插入4,4-N,N′-二咔唑基联苯(CBP)超薄层,制备了结构为ITO/NPB/CBP(xnm)/CBP:Ir(ppy)3/BCP/Alq3/LiF/Al有机电致磷光器件。与未插入CBP超薄层的器件相比,CBP超薄层的引入可以有效阻挡Ir(ppy)3的三线态能量通过Dexter能量转移到HTL的NPB中,减少无辐射能量损失,提高了器件发光效率。调整CBP薄层的厚度,当x为3nm时,器件的效率提高幅度最大,从x为0nm时的9.0cd/A提高到16.9cd/A。     

逐层剥离对激光诱导残余应力场影响的数值模拟

为评价激光冲击强化效果,通常采用X射线衍射法(XRD)测定工件的残余应力分布。由于X射线穿透深度一般在微米数量级,为获得工件深度方向上的残余应力分布规律,常采用电解抛光的方法逐层剥离工件表面材料。逐层剥离过程改变了工件表面的边界条件,使得残余应力分布发生了改变,导致XRD实验测得的残余应力与未剥离前不同。本文采用有限元数值模拟方法研究了剥离过程对激光诱导残余应力场分布的影响。结果表明:在残余压应力区域,剥离材料后内部的残余压应力较剥离前增大,残余压应力增加程度随着剥离深度的增大而增加;剥离表面较浅一层材料时,整体残余应力场的分布变化较小,且有利于消除激光冲击强化产生的"残余应力洞"。该研究对基于XRD实验测定的残余应力修正具有一定的指导意义。