键合界面对面发射激光器光与热性质的影响

通过界面有效吸收系数的计算及界面对腔模的反射率的影响可知,采用双面键合技术制备面发射激光器应使键合界面处于驻波场分布零点位置,同时界面厚度应该小于20 nm以使器件光学性能受界面吸收系数的影响较小.采用有限元方法分析VCSEL温度分布,结果证实薄的键合界面使VCSEL有源区温度对界面的热导率和电导率改变不敏感,而厚的键合界面将可能使有源区温度有较大地升高,给器件带来严重的不良影响.亲水键合和疏水键合的SEM照片说明疏水处理界面较薄,适合用于器件的制备.而亲水处理界面厚度>40 nm,对器件的光、热特性不利 关键词： 键合 面发射激光器 热导率 电导率     

厚度偏差对VCSEL的反射谱和反射相移的影响

采用光学传输矩阵方法分析了厚度偏差对VCSEL的反射谱和反射相移产生的影响。结果表明,反射镜和VCSEL中各层厚度的偏大,将使反射镜的中心波长以及VCSEL的模式波长向长波方向移动,而反射镜和VCSEL中各层厚度的偏小,将使反射镜的中心波长以及VCSEL的模式波长向短波方向移动。将键合界面离有源区稍微远一些,有利于减小其厚度偏差对VCSEL的模式波长的影响。     

Ge/Si异质键合半/绝接触界面态对异质结光电输运特性的影响研究

Ge/Si异质键合技术作为一种新型的通用材料制备工艺,在制备高质量Si基Ge薄膜方面展现出巨大的潜力,是研制高性能Ge/Si光电器件的备选方案之一。现阶段主流的直接键合和等离子体键合方法在制备Ge/Si薄膜时都容易在Ge/Si键合界面处引入纳米氧化锗层(GeO₂),导致Ge/GeO₂及GeO₂/Si半/绝接触界面存在界面态,从而器件性能受影响。基于载流子三大输运方程、非局域隧穿模型及半经典量子解法,构建了低温Ge/Si异质键合界面,研究了键合界面的界面态密度(ISD)对Ge/Si异质结的载流子电学输运、光吸收、复合及高频响应等性能的影响。结果表明,随着ISD的增加,Ge/Si异质结的暗电流增大,同时界面态对载流子的俘获能力加强,导致总电流减小,光谱响应减弱。另外,ISD的增加导致Ge层内的电场减小,高频特性变差。为获得性能良好的键合Ge/Si异质结,ISD必须低于1×10¹² cm^-2。该研究结果为高质量Si基Ge薄膜及高性能Ge/Si光电器件的制备提供了理论指导。     

InGaAs/Si键合界面a-Si键合层厚度对InGaAs/Si雪崩光电二极管性能的影响

为从根本上阻断InGaAs/Si之间的失配晶格,获得低噪声的InGaAs/Si雪崩光电二极管,理论上在InGaAs/Si键合界面插入超薄a-Si键合层,彻底隔断键合界面异质晶格,同时保证InGaAs吸收层和Si倍增层超高的晶体质量和良好的电学传输.模拟了a-Si键合层厚度对InGaAs/Si雪崩光电二极管性能影响.由于...     

亚毫安阈值的1.3μm垂直腔面发射激光器

设计并研制了室温连续工作的单模13 μm垂直腔面发射激光器（VCSEL）,阈值电流为051 mA,最高连续工作温度达到82℃,斜率效率为029 W/A.采用InAsP/InGaAsP应变补偿多量子阱作为有源增益区,由晶片直接键合技术融合InP基谐振腔和GaAs基GaAs/Al（Ga）As分布布拉格下反射腔镜,并由电子束蒸发法沉积SiO₂/TiO₂介质薄膜上反射腔镜形成13 μm VCSEL结构.讨论并分析了谐振腔模式与量子阱增益峰相对位置对器件性能的影响. 关键词： 垂直腔面发射激光器 晶片直接键合 应变补偿多量子阱     

基于智能剥离技术的SOI材料制备

优化了硅片低温直接键合与智能剥离技术的工艺流程，在550℃，2.1×10^-2 Pa条件下制备了SOI材料，其顶层单晶Si膜的表面粗糙度为8.5 nm，缺陷密度为90 cm^-2，键合强度达到153.7 kg/cm²，形成的SOI结构除了可以形成三维集成电路中有源层间良好的绝缘层，避免了高温过程对有源层器件结构、材料及性能的影响，还能为三维集成电路后续有源层的制造提供高质量的单晶硅材料. 关键词： 绝缘体上硅 智能剥离 低温直接键合     

直接键合InP-GaAs结构界面的特性研究

通过对直接键合InP-GaAs结构的红外吸收光谱分析以及断面扫描电子显微镜观察发现，样品制备过程中不均匀的外加压强导致InP-GaAs交界面局部出现了不连续过渡的空间层，实验上将熔融石蜡渗透并被填充到该空间层，利用其对3.509μm波长光的强烈吸收特性可表征 这种局部的键合不连续区域，二维扫描测试样品不同区域的吸收谱得到3.509μm波长吸收强 度等值线图，从而描绘出外加压强的不均匀分布.实验上通过改进键合装置的施压均匀性， 得到了连续过渡界面且均匀键合的InP-GaAs结构，利用这种均匀键合技术有望制备大尺寸器 件例如光学微腔等. 关键词： 晶片直接键合 界面 红外吸收光谱     

直接键合的三结太阳能电池研究

本文研制了直接键合的三结GaInP/GaAs/InGaAsP太阳电池.直接键合技术可以减少晶格不匹配的材料在外延生长过程中产生的线位错和面缺陷,将缺陷限制在界面几十纳米的薄层而不向内扩散,是未来实现高效多结电池的发展趋势之一.此类电池国内鲜有报道.本文键合三结电池的键合界面采用p+GaAs/n+InP结构,得到电池开路电压3.0 V,在电池结构没有优化的情况下获得效率24%,表面未做减反膜.开路电压表明三结电池实现了串联,为单片集成的高效多结电池提供了新的途径.对实验结果进行了分析并给出了改进措施.     

吸收对垂直腔面发射激光器光学特性的影响

采用光学传输矩阵方法，详细分析了反射镜以及键合界面的吸收对垂直腔面发射激光器光学特性的影响. 结果表明，反射镜以及键合界面的吸收对反射镜和垂直腔面发射激光器的反射率和势透射率有较大影响，而对反射镜中心波长处的反射相移以及垂直腔面发射激光器模式的反射相移和模式位置影响很小. 随着反射镜以及键合界面的吸收增大，反射镜中心波长处的反射率逐渐减小，垂直腔面发射激光器的模式反射率变化则是先急剧减小，达到一个极小值，然后再逐渐增大，而反射镜中心波长处以及垂直腔面发射激光器模式处的势透射率则都是迅速降低的. 此外，将有吸收的键合界面离有源区的距离远一些，有利于提高垂直腔面发射激光器模式处的光输出效率.     

考虑空间电荷层效应的氧离子导体电解质内载流子传输特性

晶界或异质界面诱发的空间电荷层(space charge layer,SCL)效应,被认为是氧离子导体电解质内界面附近区域载流子传输特性显著区别于体相区域的关键原因之一.现有研究多采用Poisson-Boltzmann(PB)方程预测SCL效应的影响规律,但其基于载流子电化学平衡假设,无法用于载流子存在宏观运动的工况,极大限制了相关传输机理研究.本文耦合Poisson方程和载流子质量守恒方程,建立了适用于载流子具有宏观运动时氧离子导体内载流子传输过程的模型,推导了控制SCL效应的关键无量纲参数.聚焦固体氧化物燃料电池中常用的AO2-M2O3氧离子导体电解质,对比研究了传统PB方程和本文建立的Poisson-载流子质量守恒耦合方程的预测结果可靠性.进一步采用耦合模型深入分析了考虑SCL效应时氧离子导体内部氧空位传输机理,发现导体界面电流密度增大导致SCL电阻先减小后增大.增大无量纲Debye长度(表征空间电荷层厚度与导体厚度的比值)可显著增大SCL电阻.当驱动氧空位移动的过电势与热势数量级相当时,增大无量纲电势(表征过电势与热势的比值)导致SCL电阻增大;当过电势远小于热势时,改变无量纲电势对氧空位传输过程几乎无影响.本文研究结论可为通过合理设计晶界或异质界面以改善氧离子导体内载流子传输能力及最终提高相关电化学器件性能提供理论依据.     

垂直腔面发射激光器电、光特性分析

根据增益波导垂直腔面发射激光器(VCSELs)直接耦合的准三维理论模型,通过有限差分法对泊松方程、注入电流密度、载流子浓度和光场分布方程求自洽解,研究了垂直腔面发射激光器的电特性和光波导特性.计算结果表明,氧化限制层位置是影响激光器特性的主要因素之一,如果忽略N型DBR层的影响,将与实际的垂直腔面发射激光器有较大偏差.     

Characterization of the hole transport and electrical properties in poly(9,9-dioctylfluorene)

A systematic study of the hole transport and electrical properties in blue-emitting polymers as poly(9,9-dioctylfluorene) (PFO) has been performed. We show that the temperature dependent and thickness dependent current density versus voltage characteristics of PFO hole-only devices can be accurately described using our recently introduced improved mobility model based on both the Arrhenius temperature dependence and non-Arrhenius temperature dependence. Within the improved model, the mobility depends on three important physical quantities: temperature, carrier density, and electric field. For the polymer studied, we find the width of the density of states σ=0.115 eV and the lattice constant a=1.2 nm. Furthermore, we show that the boundary carrier density has an important effect on the current density versus voltage characteristics. Too large or too small values of the boundary carrier density lead to incorrect current density versus voltage characteristics. The numerically calculated carrier density is a decreasing function of distance from the interface. The numerically calculated electric field is an increasing function of distance. Both the maximum of carrier density and minimum of electric field appear near the interface.     

Management of the electrical injection uniformity in broad-area top-emitting VCSELs

The electrical properties of broad-area 850 nm top emitting VCSELs have been investigated in order to improve carrier injection uniformity in their active zone. First, we have demonstrated using an electrical simulation tool that a multi-point localized injection design associated with a spreading layer at the top of the device (ITO) can lead to a significant improvement of carrier injection and on its spatial distribution. Secondly, the electrical contrast achievable by applying this method with localized etchings has been experimentally measured. Finally, stripe-shaped devices with output power up to 50 mW in a continuous-wave operation at room temperature have been demonstrated.     

Electrical and dielectric characterization of Au/ZnO/n-Si device depending frequency and voltage

Au/Zn O/n-type Si device is obtained using atomic layer deposition(ALD) for Zn O layer, and some main electrical parameters are investigated, such as surface/interface state(Nss), barrier height(Φb), series resistance(Rs), donor concentration(Nd), and dielectric characterization depending on frequency or voltage. These parameters are acquired by use of impedance spectroscopy measurements at frequencies ranging from 10 k Hz to 1 MHz and the direct current(DC) bias voltages in a range from-2 V to +2 V at room temperature are used. The main electrical parameters and dielectric parameters,such as dielectric constant(ε"), dielectric loss(ε"), loss tangent(tan δ), the real and imaginary parts of electric modulus(M and M), and alternating current(AC) electrical conductivity(σ) are affected by changing voltage and frequency. The characterizations show that some main electrical parameters usually decrease with increasing frequency because charge carriers at surface states have not enough time to fallow an external AC signal at high frequencies, and all dielectric parameters strongly depend on the voltage and frequency especially in the depletion and accumulation regions. Consequently, it can be concluded that interfacial polarization and interface charges can easily follow AC signal at low frequencies.     

Current spreading and series resistance of proton-implanted vertical-cavity top-surface-emitting lasers

In this paper, the current flow through the whole volume of the proton-implanted Vertical-Cavity top-Surface-Emitting Lasers (VCSELs) is analysed in detail. A simple approximate analytical relation was derived for a radial distribution of the current density entering active regions of those lasers. This distribution is nearly uniform in the case of VCSELs with a very small active region, but is becoming more and more non-uniform with an increase in its size. In VCSELs with very large active regions, current is flowing practically only within a narrow annular area close to the active-region perimeter. The VCSEL series electrical resistance is determined as a function of its active-region radius.     

沟道宽度对ZnO-TFT电学性能的影响

用射频磁控溅射法生长的ZnO薄膜作为有源层,制备出了ZnO基薄膜晶体管(ZnO-TFT),并在空气环境下350℃退火1 h,研究了沟道宽度对ZnO-TFT器件性能的影响。实验结果表明:阈值电压随着沟道宽度的减小而增加,这是由于沟道越窄,载流子被捕获的几率越大,在相同栅压下沟道内可动载流子浓度越小,相应的阈值电压就越大;饱和迁移率随着沟道宽度的减小而增加,认为这是由源/漏电阻的侧壁效应及边缘电子场效应引起的附加电流所致。     

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采用PSpice软件进行了等离子体流动控制实验系统的电特性仿真。将等离子体放电建模为分段非线性的电压控制电流源子模块,较好地解决了等离子体流动控制系统电特性仿真的关键问题。在此基础上,对等离子体流动控制实验系统进行了仿真。仿真结果证实了等离子体放电模型的有效性,可用于指导进一步仿真和流动控制实验系统的改进。     

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用Matlab软件对大气压均匀辉光放电等离子体(OAUGDP)激励器系统的电特性进行了仿真。在仿真模型中,等离子体放电被建模成一个电压控制的电流源:当加在气隙上的电压超过等离子体产生电压时,该受控电流源接通;电流源的输出电流和所加电压之间遵循幂律。建立了一个OAUGDP激励器系统中等离子体放电的电路模型。仿真结果与实际激励器系统的实验数据很吻合。仿真结果表明,在不同的运行条件下,放电电流与电压之间遵循不同的指数幂律,仿真放电电流波形也不同。     

Electrical and piezoresistive properties of ion beam deposited DLC films

In present study diamond like carbon (DLC) films were deposited by closed drift ion source from the acetylene gas. The electrical and piezoresistive properties of ion beam synthesized DLC films were investigated. Diode-like current–voltage characteristics were observed both for DLC/nSi and DLC/pSi heterostructures. This fact was explained by high density of the irradiation-induced defects at the DLC/Si interface. Ohmic conductivity was observed for DLC/nSi heterostructure and metal/DLC/metal structure at low electric fields. At higher electric fields forward current transport was explained by Schottky emission and Poole–Frenkel emission for the DLC/nSi heterostructures and by Schottky emission and/or space charge limited currents for the DLC/pSi heterostructures. Strong dependence of the diamond like carbon film resistivity on temperature has been observed. Variable range hopping current transport mechanism at low electric field was revealed. Diamond like carbon piezoresistive elements with a gauge factor in 12–19 range were fabricated.     

非欧姆注入单层有机发光器件低场下电流传导温度特性的数值研究

温度是影响有机发光器件特性的一个重要因素,考虑了电流的注入限制和体限制之后,运用数值方法,研究了在低电场下温度对单层有机发光器件的J-V特性以及电场和载流子在有机层中的分布的影响。结果表明,在一定电压下,温度升高时,器件电流增大,有机层中载流子及其梯度分布增大,电场强度分布梯度也增大。并且当温度逐渐升高时,器件的电流传导将趋向于体限制,而当温度逐渐降低时,器件电流传导将趋向于注入限制,此时有机层内各处电场强度趋于均匀。并且结果表明,数值结果与实验结果符合得比较好。