The effects of strain and surface roughness scattering on the quasi-ballistic characteristics of a Ge nanowire p-channel field-effect transistor

The effects of strain and surface roughness scattering on the quasi-ballistic hole transport in a strained gate-all-around germanium nanowire p-channel field-effect transistor （pFET） are investigated in this work. The valence subbands are shifted up and warped more parabolically by the influence of HfO2 due to the lattice mismatch. However, the boundary force only shifts the subbands downwards and has little effect on the reshaping of bands. Strain induced by HfO2 increases both the hole mobility and ON-current （/ON）, but has little effect on the hole mobility. The/ON is degraded by the surface roughness scattering in both strained and unstrained devices.     

Quadratic nonlinear response to 1.56-μm continuous wave laser in semi-insulating GaAs

The nonlinear photoresponse to a 1.56μm infrared continuous wave laser in semi-insulating （SI） galliu- marsenide （GaAs） is examined. The double-frequency absorption （DFA） is responsible for the nonlinear photoresponse based on the quadratic dependence of the photocurrent separately on the coupled optical power and bias voltage. The electric field-induced DFA remarkably affects the native DFA in SI GaAs. The surface electric field or the surface band-bending of SI GaAs significantly affects the magnitude variation of the Dhotocurrent and dark current     

Emission enhancement in Er^3＋/Pr^3＋-codoped germanate glasses and their use as a 2.7-μm laser material

Emission enhancement at 2.7 μm is observed in Er^3＋/Pr^3＋--codoped germanate glasses when pumped by a 980-nm laser diode. Significant reductions in 1.5-μm emission and upeonversion intensity indicate efficient energy transfer between Er^3＋ and Pr^3＋; the energy transfer efficiency is as high as 77.4%. The mechanisms of energy transfer are discussed in detail. The calculated emission cross-section of Er^3＋/Pr^3＋- codoped germanate glass is 8.44× 10 ^-21 cm^2, which suggests that Er^3＋/Pr^3＋-codoped germanate glass can be used to achieve efficient 2.7-μm emission.     

Enhanced NIR emission in Ce^3＋/Er^3＋-doped YAG induced by Bi^3＋ doping

Ce^3＋/Er^3＋/Bi^3＋ triply-doped yttrium aluminum garnet （YAG） is synthesized using co-precipitation method. The Bi^3＋ concentration-dependent near-infrared （NIR） emission behavior is systemically in- vestigated. The NIR emission of Er^3＋ ions at 1531 nm is enhanced threefold by the addition of 7 mol% Bi^3＋. Bi^3＋doping results in the formation of exciton in YAG and the variation in the local environment of the doped rare-earth ions. The enhancement in NIR luminescence is ascribed to the combined effects of the sensitization of exciton→Ce^3＋ →Er^3＋ and the Bi^3＋ doping-induced adjustment of the local environment for Ce^3＋ and Er^3＋ ions.     

Cr4+掺杂Li1.14Zn1.43SiO4透明微晶玻璃近红外宽带光谱特性

采用高温熔融法和热处理制备了Cr⁴⁺掺杂Li_1.14Zn_1.43SiO₄微晶玻璃, 探讨了不同热处理温度下样品的物相、微观形貌及发光性能. 结果表明: 580℃热处理2h得到的微晶玻璃, Li_1.14Zn_1.43SiO₄微晶的粒径约为5nm, 在808nm的二极管激发下, 可观察到中心波长位于1226nm, 半高宽为230nm的近红外宽带发射峰, 荧光寿命约为200.73±1.71μs. 随着热处理温度的升高, Cr⁴⁺离子所处的晶体场环境发生了变化, 且可以观察到样品吸收光谱发生微弱的蓝移, 而荧光光谱发生少量的红移, 分析了晶体场环境变化对样品发光性能的影响. 关键词： 铬离子 微晶玻璃 超宽带发光 晶体场     

激光诱导叶绿素荧光寿命的测量及其特性分析

提出了一种用于评估植物生长状况及环境监测的激光诱导叶绿素荧光寿命测量方法. 采用波长355 nm的激光作为光源激发叶绿素荧光, 由光电倍增管接收其荧光信号, 由于被测叶绿素荧光衰减函数与激光脉冲、仪器响应函数卷积在一起, 根据它们的特性, 运用时间分辨测量法分别测得叶绿素荧光及其背景信号, 并结合一种新型解卷积算法可分离出真实的叶绿素荧光衰减函数, 从而获取叶绿素的荧光寿命. 测试结果表明: 该方法能够实现叶绿素荧光寿命的高精度实时监测, 对不同叶绿素含量的溶液荧光寿命进行了测试, 证明叶绿素含量与其荧光寿命具有相关性, 并且拟合了叶绿素含量与荧光寿命的标定曲线. 关键词： 荧光寿命 激光诱导荧光 时间分辨测量法 叶绿素含量     

原子介质中的多波混频相干控制

多波混频是一种重要的非线性光学过程,其在非线性光学和量子信息科学中有重要的应用.本文详细讲述了该领域的进展.在频域中,首先通过电磁诱导透明在实验上得到了共存的四六波混频信号,继而观察到了它们之间伴随着能量交换和时空干涉的相互竞争.此外,两个竞争的四六波混频之间的抑制增强以及相应的AT分裂也被实验证实了.在空间域中,研究了因为两束泵浦光之间干涉导致的电磁诱导光栅,对多波混频信号的空间移动和分裂也进行了讨论,并且得到了带隙孤子,涡旋孤子,有荷偶极孤子,以及二维表面孤子.这些概念可以扩展到量子领域,并且与之相关的一些效应具有研究价值.本文同时也讨论了多波混频在腔量子电动力学中,里德堡态中,以及全固态量子计算中的发展前景以及潜在应用.     

Influences of Mg^2＋ ion on dopant occupancy and upconversion luminescence of Ho^3＋ ion in LiNbO3 crystal

The effects of a Mg^2＋ ion on the dopant occupancy and upconversion luminescence of a Ho^3＋ ion in LiNbO3 crystal are reported. The birefringence gradient of the crystal is measured to investigate the optical homogeneity. The X-ray powder diffraction spectrum and the upconversion luminescence are used to investigate defect structure and spectroscopic properties of Mg,Ho：LiNbO3. Under 808-nm excitation, blue, red, and very intense yellow-green bands are observed. Based on the energy levels of Ho^3＋ in LiNbO3, and the pump intensity dependence of the observed emission, an excitation scheme is presented. The upconversion emission spectra reveal an enhancement of upconversion intensity when the Mg^2＋ ions are introduced into Ho：LiNbO3. The main upconversion mechanism is discussed in this work.     

Tm3+,Yb3+共掺钨酸钙多晶材料的上转换发光及荧光温度特性

采用高温固相法制备了Tm³⁺,Yb³共掺CaWO₄多晶材料. 980 nm二极管激光器激发下,在可见区获得了¹G₄→³H₆,¹G₄→³H₄,³H₂,³H₃→³H₆ 跃迁产生的上转换荧光. 讨论了Yb³⁺ 离子浓度的变化对Tm³⁺ 的上转换发光强度的影响,同时根据荧光强度比的方法研究了689 和705 nm 红色上转换荧光在313–773 K 范围内的温度特性. 结果表明：基于Tm³⁺,Yb³⁺ 共掺CaWO₄ 多晶材料的红色上转换荧光可以实现温度监测,其测温的最大灵敏度值为5.7×10^-4 K^-1,相应的测量温度为458 K. 关键词： 上转换发光 3+')" href="#">Tm³⁺ 钨酸钙 荧光温度传感     

功能层厚度对叠层有机电致发光器件出光性能影响的数值研究

功能层厚度是影响有机电致发光器件出光效率的主要因素之一,故获得不同功能层厚度对器件出光特性的影响规律是制备高性能器件的重要基础. 本文基于薄膜光学原理、电偶极子辐射理论及Fabry-Pérot微腔原理,建立了结构为glass/ITO/N,N0-bis（naphthalen-1-yl）-N,N0-bis（phenyl）-benzidine（NPB）/tris（8-hydroxyquinoline）aluminum（Alq₃）/molybdenum trioxide（MoO₃）/NPB/Alq₃/Al的叠层有机电致发光器件的光学模型,系统地研究了各个功能层厚度对叠层有机电致发光器件出光强度的影响,得到了功能层厚度对器件出光强度影响的规律. 该模型的建立与所获得的结果可对深入了解叠层有机电致发光器件的工作机理以及制备高性能的器件提供一定的帮助. 关键词： 叠层有机发光器件 出光特性 厚度 数值研究