Impurity Deionization Effects on Surface Recombination DC Current-Voltage Characteristics in MOS Transistors

Impurity deionization on the direct-current current-voltage characteristics from electron-hole recombi-nation(R-DCIV)at SiO<,2>/Si interface traps in MOS transistors is analyzed using the steady-state Shockley-Rea-Hall recombination kinetics and the Fermi distributions for electrons and holes.Insignificant distortion is observed over 90%of the bell-shaped R-DCIV curves centered at their peaks when impurity deionization is excluded in the theory.This is due to negligible impurity deionization because of the much lower electron and hole concentrations at the interface than the impurity concentration in the 90% range.     

用激射延迟法研究DH激光器的复合性质

利用激射延迟方法,对GaA_3-Al_(0.3)Ga_(0.7)A_3DH激光器的复合机制进行了分析和测量.得出了只有同时考虑双分子过程辐射复合和非辐射复合两种复合机理,才能对DH激光器的激射延迟性质进行较全面研究的结论.并由此可提供一种测定辐射复合系数和少数载流子寿命的方法.     

Modeling of Recombination in HgCdTe

Minority carrier recombination lifetime calculations for narrow-gap semiconductors are of direct practical interest in establishing whether a material’s recombination is extrinsically or intrinsically limited, and therefore in guiding research and development programs regarding material quality improvements. We describe efforts to obtain accurate electronic band structures of HgCdTe alloy-based materials with infrared energy gaps and employ them to evaluate Auger recombination lifetimes. We use a 14-band k · p formalism to compute and optimize electronic band structures, and use the obtained electronic energies and matrix elements directly in the numerical evaluation of Auger and radiative lifetimes.     

突变 HBT准费密能级分裂与复合电流

要精确描述HBT的复合电流,必须考虑异质结界面处的准费密能级分裂。而重掺杂改变了分裂量的大小．从而使复合电流发生与之相对应的变化。本文利用更准确的考虑了重掺杂效应影响的准费密能级分裂模型,计算了各种复合电流。通过比较得出准费密能级分裂对复合电流的重要性。     

GaAs表面及Al_xGa_（1－x）As／GaAsHBT外基区表面（NH_4）_2S／SiN_x钝化工艺研究

分析了ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓＨＢＴ外基区表面复合电流及外基区表面复合速度对直流增益的影响，用光致发光（ＰＬ）谱和Ａｌ／ＳｉＮｘ－Ｓ／ＧａＡｓＭＩＳ结构Ｃ－Ｖ特性，研究了ＧａＡｓ表面（ＮＨ４）２Ｓ／ＳｉＮｘ钝化工艺的效果及其稳定性。结果表明，ＥＣＲ－ＣＶＤ淀积ＳｉＮｘ覆盖并在Ｎ２气氛中退火有助于改善ＧａＡｓ表面硫钝化效果的稳定性。在此基础上形成了一套包括（ＮＨ４）２Ｓ处理、ＳｉＮｘＥＣＲ－ＣＶＤ淀积及退火并与现有ＨＢＴ工艺兼容的外基区表面钝化工艺，使发射区面积为４×１０μｍ２的器件增益比钝化前提高了４倍，且６０天内不退化。     

钙离子复合激光的实验研究

报道了一台平均功率为５０ｍＷ的钙离子复合激光实验装置。通过改变缓冲气体压强、脉冲重复率及输入电功率等参量，分析了Ｈｅ－Ｃａ＋复合激光的工作特性，测量了一些参量之间的关系     

类氦等电子系列离子的双电子复合速率系数

给出了一套计算类氦等电子数系列离子双电子复合速率系数的解析公式，这套公式能快速、准确地给出类氦离子从Ｂ３＋到Ｘｅ５２＋、电子温度在０．１ｋｅＶ到７０ｋｅｙ范围内各离子的双电子复合速率系数。作为一个例子，计算了类氦硅离子双电子复合速率系数，并与Ｋａｒｉｍ等人的理论从头计算的结果作了比较，二者十分一致。     

Charge Recombination Dynamics in Organic Photovoltaic Systems with Enhanced Dielectric Constant

Increasing the dielectric constant of organic photovoltaic materials to reduce recombination rates has long been pursued, however, material modification often results in the modification of multiple device characteristics, making system comparison difficult. In this study, a fullerene derivative with an increased blend dielectric constant is examined by the addition of a triethylene glycol appendage to the fullerene (TEG‐PCBM). Density functional theory calculations show a small change to the permanent dipole moment between TEG‐PCBM and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₀BM) resulting in similar solubility, morphology, and device performance. TEG‐PCBM is blended with donors P3HT and PTB7‐Th and a comparable performance to PC₆₀BM is found. This model system shows the rarely reported characteristic of an increase in the dielectric constant while leaving its other properties unaltered. Looking at light intensity effects on open‐circuit voltage (V_oc), short‐circuit current (J_sc), and fill factor (FF) along with exciton dissociation efficiency, it is observed that when switching to the TEG‐ modified fullerene derivative, geminate recombination is not reduced, and Shockley–Read–Hall recombination is increased. While triethlyene glycol appendages may prove to be ineffective in improving recombination through increased dielectric constant, an approach for studying recombination in future high dielectric systems is provided.     

The Effect of the Microstructure on Trap‐Assisted Recombination and Light Soaking Phenomenon in Hybrid Perovskite Solar Cells

Despite the rich experience gained in controlling the microstructure of perovskite films over the past several years, little is known about how the microstructure affects the device properties of perovskite solar cells (HPSCs). In this work, the effects of the perovskite film microstructure on the charge recombination and light‐soaking phenomenon in mixed halide HPSCs are investigated. Devices with noncompact perovskite morphology show a severe light soaking effect, with the power conversion efficiency (PCE) improved from 3.7% to 11.6% after light soaking. Devices with compact perovskite morphology show a negligible light soaking effect, with PCE slightly increased from 11.4% to 11.9% after light soaking. From device investigations, photoluminescence, and impedance spectroscopy measurements, it is demonstrated that interface electron traps at the grain boundaries as well as at the crystal surface dominate the light soaking effect. Severe trap‐assisted recombination takes place in HPSCs using noncompact films, while it is effectively eliminated in devices with compact films. Moreover, how the grain size of the perovskite film affects the light soaking phenomenon is investigated. In the case of compact perovskite films, the size of the grains has a limited effect on the light soaking. In these compact films, grains are fused and trap states are effectively reduced.     

Recombination parameters for antimonide-based semiconductors using the radio frequency photoreflectance technique

Radio-frequency (RF) photoreflectance measurements and one-dimensional device simulations have been used to evaluate bulk and surface recombination parameters in doubly capped, 0.50–0.59-eV, p-type InGaAsSb epitaxial materials. The InGaAsSb lifetime structures with variable active-layer thicknesses are used to extract the surface recombination velocity (SRV), while samples with different active-layer doping concentrations have been used to determine the Auger and radiative recombination coefficients. The RF photoreflectance measurements and analysis are compatible with a radiative recombination coefficient (B) of approximately 3×10⁻¹¹ cm³/s, Auger coefficient (C) of 1×10⁻²⁸ cm⁶/s, and SRV of ∼10³ cm/s or lower for 0.50–0.59 eV, doubly capped, p-type InGaAsSb epitaxial layers.     

双层异质结器件载流子复合位置的研究

载流子的复合是有机电致发光过程的一个重要环节,它直接影响着器件的效率,稳定性,寿命等性能。以双层器件ITO／N,N＇-Diphenyl-N,N＇-bis（1-naphthyl）-（1,1＇-biphenyl）-4,4＇-diamine（NPB）／tri-（8-hydroxy-quinoline）-aluminum（Alq3）／Mg：Ag为基础,以红光掺杂剂4-（dicyanomethylene）-2-t-butyl-6-（1,1,7,7-tetramethyljulolidyl-9-enyl）-4H-pyran（DCJTB）为探针,通过改变在Alq3层中掺杂层的厚度,研究了双层异质结器件中载流子的复合位置。结果表明,对于双层器件NPB／Alq3,载流子的复合及激子的辐射衰减位于界面处的Alq3层0～10nm范围内。     

类钠Ar~(7 )离子内壳层双电子复合

研究了类钠Ａｒ７＋离子内壳层双电子的复合激发截面，此结果对研制Ｘ射线激光有一定的参考价值，并给出了２ｐ５３ｐ２和２ｐ５３ｄ２组态的双电子复合截面     

一种基于矩阵重组的功率倒置改进算法

针对功率倒置(Power Inversion,PI)算法信噪比恶化问题,推导了最小均方误差准则下最优权矢量组成,提出了处理增益更高、工作范围更广的改进算法.算法通过对接收信号协方差矩阵进行特征分解,根据特征值分布特点舍去噪声特征向量,组成新的协方差矩阵,得到具有指向性的最优权值矢量.仿真结果表明,与传统PI算法相比,改...     

挑战、成因与中国电信业的战略重组(上)

目前我国电信行业依然面临着多重挑战,主要表现在重复建设、规模经济效益弱化、市场缺乏有效调解机制、产业链布局不合理等。其成因主要是产业组织结构调整不到位、产权结构和内部治理机制不合理,以及人力资产的路径依赖等。新一轮电信改革有三大目标,其经济目标一是提高对国民经济贡献率,二是对产业链及旁侧产业的拉动。政治目标是必须从根本上体现全体国民的总体福利,主要通过资费水平的下调和服务质量的提高来体现。因此,如何通过新的改革,控制或降低电信行业的垄断租金,使其转化为消费者剩余,也应成为新一轮改革的重要目标。社会目标是更好地处理好普遍服务问题。     

Relationship of Band-Edge Luminescence to Recombination Lifetime in Silicon Wafers

In recent years, intrinsic luminescence has been used as a method to characterize the recombination lifetime of crystalline silicon. The assumption is that the steady-state intrinsic photoluminescence at 1.09 eV (1.134 μm) can be related to the recombination lifetime. In this work, we measured the band-edge photoluminescence (PL) intensities of a number of single-crystal wafers. The resistivity in the wafer set ranges from 1 to 11,000 ohm-cm under constant excitation intensity. We then measured the PL spectra and recombination lifetimes of these wafer sets under a variety of conditions. The lifetime was measured using resonant-coupled photoconductive decay (RCPCD) in both air ambient and an iodine/methanol solution. The same procedure was used for the PL spectra. Plots of the measured lifetime versus the PL intensity showed weak correlation between the two quantities in air ambient. However, there is a positive relationship between the near-bandgap PL intensity and the recombination lifetime for passivated surfaces. Some fundamental physical reasons will be used to explain these results.     

有机磷光电致发光器件中的复合宽度和外量子效率

从经验公式出发,基于T-T湮灭过程,建立了有机磷光电致发光器件中复合宽度和外量子效率的理论模型.结果表明:(1)随外加电压升高,器件的复合宽度减小,外量子效率增加;(2)随器件厚度的增加,复合宽度相应增加,但外量子效率在不同的电压下呈现不同的变化趋势;(3)外量子效率随复合电流密度的增大而显著降低.讨论了外加电压和器件厚度对复合宽度的影响,分析了外量子效率随外加电压、器件厚度及复合电流密度变化的原因.     

Recombination Through Different Types of Localized States in Organic Solar Cells

Recombination in bulk heterojunction solar cells is explored by observing the result of prolonged white light illumination, thermal annealing to high temperature, and chemical doping. Measurements of the photocurrent spectral response, the steady state photocurrent‐voltage characteristics, transient photoconductivity and the dark forward bias current on polymer:fullerene solar cells provide information about the density of states and the electronic properties. Illumination generates deep localized states in the interface gap, which act as recombination centers and also increase the diode ideality factor. Annealing induces both nanostructural and electronic changes. The coarsening of the domain structure reduces the probability that excitons reach the interfaces and also reduces the charge transfer absorption. At the same time annealing broadens the exponential band tails and increases the recombination rate. Doping introduces shallow states near the fullerene conduction band, which also act as recombination centers. The results show that recombination is through localized states of different character, depending on the circumstances.     

界面效应对半导体量子点异质结的电子能级扰动的分析

提出采用壳状结构和渐变有限深势阱模型的方法来分析界面效应对半导体量子点异质结的束缚态电子能级的扰动。模拟计算表明，对于处于强受限的量子点，界面效应明显。随着量子点的表面区域增大和量子点尺寸的减小，能级移动增加，在低能级时近似呈线性变化关系。     

用Columnar模型对电子空穴对复合逃逸产额的模拟计算

用一种比较简单的 Jaffe近似方法计算了质子在 Si O2 中的电子空穴对的逃逸率 ,讨论了辐照偏置、电场、质子入射角度、质子能量等对逃逸产额的影响 .得到了电子空穴对复合逃逸率与质子能量、电场成正比的结果 .计算结果与实验结果的比较 ,说明了 Jaffe近似方法可以比较正确地描述质子在二氧化硅中的总剂量效应 .