InGaAsSb/AlGaAsSb长波长多量子阱激光器有源区的优化设计

系统地研究了波长为2.7μm的InGaAsSb/AlGaAsSb多量子阱激光器中有源区的优化设计.分别用含应变势的6带KP模型和抛物带模型计算价带和导带的能带结构，并得到薛定谔方程和泊松方程的自洽解，由此计算量子阱在载流子注入时的增益谱.研究表明制约量子阱增益的主要因素不是跃迁矩阵元，而是粒子数反转程度，尤其是空穴填充HH1子带的概率.增加压应变或减小阱宽都会提高量子阱增益.前者降低了价带HH1子带空穴的平面内有效质量；后者拉大了价带子带间距，尽管它同时略微增加了空穴有效质量.这两种因素都导致价带顶空穴态     

InGaAsSb／AIGaAsSb长波长多量子阱激光器有源区的优化设计

系统地研究了波长为2．7μm的InGaAsSb／AlGaAsSb多量子阱激光器中有源区的优化设计，分别用含应变势的6带KP模型和抛物带模型计算价带和导带的能带结构，并得到薛定谔方程和泊松方程的自洽解，由此计算量子阱在载流子注入时的增益谱，研究表明制约量子阱增益的主要因素不是跃迁矩阵元，而是粒子数反转程度，尤其是空穴填充HHl子带的概率，增加压应变或减小阱宽都会提高量子阱增益，前者降低了价带HHl子带空穴的平面内有效质量；后者拉大了价带子带间距，尽管它同时略微增加了空穴有效质量，这两种因素都导致价带顶空穴态密度的降低，提高了空穴在HHl子带的填充概率，最终提高了量子阱的增益，所得结论与已有的实验报道相符。     

近800nm波长张应变GaAsP/A1GaAs量子阱激光器有源区的设计

张应变GaAs_(1-x)P_x量子阱是高性能大功率半导体激光器的核心有源区,基于能带结构分析优化其结构参数具有重要的应用指导意义.首先,基于6×6 Luttinger-Kohn模型,采用有限差分法计算了张应变GaAs_(1-x)P_x量子阱的能带结构,得到了第一子带间跃迁波长固定为近800 nm时的阱宽-阱组分关系,即随着阱组分x的增加,需同时增大阱宽,且阱宽较大时靠近价带顶的是轻空穴第一子带lh_1,阱宽较小时靠近价带顶的是重空穴第一子带hh_1.计算并分析了导带第一子带c_1到价带子带lh_1和hh_1的跃迁动量矩阵元.针对808 nm量子阱激光器,模拟计算了阈值增益与阱宽的关系,得到大阱宽有利于横磁模激射,小阱宽有利于横电模激射.进一步考虑了自发辐射和俄歇复合之后,模拟计算了808 nm量子阱激光器的阱宽与阈值电流密度的关系,阱宽较大时载流子对高能级子带的填充使得阈值电流密度增加,而阱宽较小时则是低的有源区光限制因子导致阈值电流密度升高,因此存在一最佳的阱宽-阱组分组合,可使阈值电流密度达到最小.本文的模拟结果可对张应变GaAs_(1-x)P_x量子阱激光器的理论分析和结构设计提供理论指导.     

固定波长应变量子阱的设计与比较

针对lnGaAsP材料,我们比较了不同应变与阱宽组合的固定波长应变量子阱特性.压应变下量子阱的应变量越大,阱宽越窄,其能带结构越理想.张应变下主要由于电子与轻空穴的偶极矩阵元比电子与重空穴的大,以及其较大的态密度,使得张应变量子阱的微分增益比压应变和匹配量子阱的大得多.如果固定的张应变量只能使第一子带为LH,第二子带为HH,则存在一个最优的阱宽,阱宽太小不能消除LHI与HH2的耦合,阱宽太大又会带来LH3与HH2的耦合,同样会有不利影响.     

光抽运半导体激光器增益特性研究

以InGaAs/GaAs应变量子阱材料为例,介绍了考虑能带及波函数的混合效应的6×6Luttinger-Kohn哈密顿量,提出用有限差分法求解含Luttinger-Kohn哈密顿量的有效质量方程,数值模拟得到导带和价带的能带结构,计算应变量子阱的跃迁矩阵元,进而用Lorentzian线形函数计算材料增益。讨论了量子阱阱宽、注入载流子浓度、温度等因素对量子阱材料增益的影响。计算结果表明,压应变使得量子阱有效带隙增大,降低了材料增益的透明电流密度,继而降低器件的阈值,改善器件的输出特性;增益峰值波长和发射波长之间合适的偏差,会使光抽运半导体激光器的阈值电流和工作电流随温度有较小的变化。     

固定波长应变量子阱的设计与比较

针对ｌｎＧａＡｓＰ材料，我们比较了不同应变与阱宽组合的固定波长应变量子阱特性压应变下量子阱的应变量越大，阱宽越窄，其能带结构越理想张应变下主要由于电子与轻空穴的偶极矩阵元比电子与重空穴的大，以及其较大的态密度，使得张应变量子阱的微分增益比压应变和匹配量子阱的大得多如果固定的张应变量只能使第一子带为ＬＨ，第二子带为ＨＨ，则存在一个最优的阱宽，阱宽太小不能消除ＬＨＩ与ＨＨ２的耦合，阱宽太大又会带来ＬＨ３与ＨＨ２的耦合，同样会有不利影响     

近800 nm波长张应变GaAsP/AlGaAs量子阱激光器有源区的设计

张应变GaAs_1-xP_x量子阱是高性能大功率半导体激光器的核心有源区,基于能带结构分析优化其结构参数具有重要的应用指导意义.首先,基于6×6 Luttinger-Kohn模型,采用有限差分法计算了张应变GaAs_1-xP_x量子阱的能带结构,得到了第一子带间跃迁波长固定为近800 nm时的阱宽-阱组分关系,即随着阱组分x的增加,需同时增大阱宽,且阱宽较大时靠近价带顶的是轻空穴第一子带lh₁,阱宽较小时靠近价带顶的是重空穴第一子带hh₁.计算并分析了导带第一子带c₁到价带子带lh₁和hh₁的跃迁动量矩阵元.针对808 nm量子阱激光器,模拟计算了阈值增益与阱宽的关系,得到大阱宽有利于横磁模激射,小阱宽有利于横电模激射.进一步考虑了自发辐射和俄歇复合之后,模拟计算了808 nm量子阱激光器的阱宽与阈值电流密度的关系,阱宽较大时载流子对高能级子带的填充使得阈值电流密度增加,而阱宽较小时则是低的有源区光限制因子导致阈值电流密度升高,因此存在一最佳的阱宽-阱组分组合,可使阈值电流密度达到最小.本文的模拟结果可对张应变GaAs_1-xP_x量子阱激光器的理论分析和结构设计提供理论指导.     

应变Si/(001)Si1-xGex空穴有效质量各向异性

基于应变Si/(001)Si1-xGex材料价带E(k)-k关系模型,研究获得了其沿不同晶向的空穴有效质量.结果表明,与弛豫材料相比,应变Si/(001)Si1-xGex材料价带带边(重空穴带)、亚带边(轻空穴带)空穴有效质量在某些k矢方向变化显著,各向异性更加明显.价带空穴有效质量与迁移率密切相关,该研究成果为Si基应变PMOS器件性能增强的研究及导电沟道的应力与晶向设计提供了重要理论依据.     

基于两端自发荧光辐射的808nm半导体激光器增益偏振特性实验表征和能带分析

通过半导体激光器两端的放大自发荧光辐射可以获取器件的光学增益信息. 本文利用这一新的增益实验测量方法, 开展了对连续运行的808nm GaAs/AlGaAs量子阱激光器横向电场 (TE)与磁场(TM)偏振增益特性的实验研究. 通过将实验结果与理论增益曲线对比, 分析了非应变GaAs量子阱TE和TM极化偏振对应的空穴子能带随注入电流的变化规律, 以及激光器在连续运行状态下的实际增益状态和影响因素. 关键词： 半导体激光器 增益测量 偏振 量子阱和能带     

应变Si1－xGex/(111)Si空穴有效质量模型

利用应变Si_1-xGe_x/(111)Si材料价带E(k)-k关系,研究获得了沿不同晶向的空穴有效质量,并在此基础上,建立了空穴各向同性有效质量模型.结果表明,与弛豫材料相比,应变Si_1-xGe_x/(111)Si材料价带带边空穴有效质量各向异性更加显著,带边空穴各向同性有效质量随Ge组分明显减小.该研究成果可为Si基应变PM 关键词： 1-xGe_x')" href="#">应变Si_1-xGe_x 空穴有效质量 价带     

光纤光栅的温度增敏实验

用热膨胀系数较大的聚合物材料对光纤光栅进行封装处理,极大地提高了光纤光栅的温度灵敏度。我们将光纤光栅封装于两种不同的聚合物材料中,其温度灵敏度分别提高6倍和23倍之多。这是迄今有文献报道的最大的光纤光栅温度灵敏度。     

Analysis of linewidth enhancement factor for compressively strained AlGaInAs and InGaAsP quantum well lasers

We have compared and analyzed theoretical investigation for the possibility of extreme reductions in the linewidth enhancement factor (??-factor) in strained layer quantum-well (QW) lasers between AlGaInAs and InGaAsP material. Valence band effective masses and optical gain in both types of QW lasers under compressive strain have been calculated using 4 ×?4 Luttinger?CKohn Hamiltonian. We have used Kramers?CKronig relations to calculate the refractive index change due to carrier induced. The ??-factor was up to 1.61 times smaller in AlGaInAs QW than in InGaAsP QW laser. The material differential modal gain and carrier induced refractive index change was found to be approximately 1.38 times larger and 1.15 times smaller respectively, in the previous material QW than in the latter QW laser. We also compared our results to the previously reported results for both QWs lasers.     

Valence band structure and density of states effective mass model of biaxial tensile strained silicon based on k·p theory

After constructing a stress and strain model, the valence bands of in-plane biaxial tensile strained Si is calculated by k·p method. In the paper we calculate the accurate anisotropy valance bands and the splitting energy between light and heavy hole bands. The results show that the valance bands are highly distorted, and the anisotropy is more obvious. To obtain the density of states (DOS) effective mass, which is a very important parameter for device modeling, a DOS effective mass model of biaxial tensile strained Si is constructed based on the valance band calculation. This model can be directly used in the device model of metal-oxide semiconductor field effect transistor (MOSFET). It also a provides valuable reference for biaxial tensile strained silicon MOSFET design.     

Valence band structure of strained Si/(111)Si_(1-x)Ge_x

The strained Si techique has been widely adopted in the high-speed and high-performance devices and circuits. Based on the valence band E-k relations of strained Si/(111)Si1-xGex, the valence band and hole effective mass along the [111] and [-110] directions were obtained in this work. In comparison with the relaxed Si, the valence band edge degeneracy was partially lifted, and the significant change was observed band structures along the [111] and [-110] directions, as well as in its corresponding hole eff...     

Numerical study on strained InGaAsP/InGaP quantum wells for 850-nm vertical-cavity surface-emitting lasers

The physical and optical properties of compressively strained InGaAsP/InGaP quantum wells for 850-nm vertical-cavity surface-emitting lasers are numerically studied. The simulation results show that the maximum optical gain, transparency carrier densities, transparency radiative current densities, and differential gain of InGaAsP quantum wells can be efficiently improved by employing a compressive strain of approximately 1.24% in the InGaAsP quantum wells. The simulation results suggest that the 850-nm InGaAsP/InGaP vertical-cavity surface-emitting lasers have the best laser performance when the number of quantum wells is one, which is mainly attributed to the non-uniform hole distribution in multiple quantum wells due to high valence band offset. PACS 42.55.Px; 78.20.-e; 78.20.Bh; 78.30.Fs     

基于锡组分和双轴张应力调控的临界带隙应变Ge_(1-x)Sn_x能带特性与迁移率计算

能带工程通过改变材料的能带结构可以显著提升其电学和光学性质,已广泛应用于半导体材料的改性研究.双轴张应力和Sn组分共同作用下的Ge_(1-x)Sn_x合金,不仅可以解决直接带隙转变所需高Sn组分带来的工艺难题,而且载流子迁移率会显著提升,在单片光电集成领域有很好的应用前景.根据形变势理论,分析了(001)面双轴张应变Ge_(1-x)Sn_x的带隙转变条件,并给出了在带隙转变临界点Sn组分和双轴张应力的关系;采用8κ·p方法,得到了临界带隙双轴张应变Ge_(1-x)Sn_x在布里渊区中心点附近的能带结构,进而计算得到电子与空穴有效质量;基于载流子散射模型,计算了电子与空穴迁移率.计算结果表明:较低Sn组分和双轴张应力的组合即可得到直接带隙Ge_(1-x)Sn_x合金,且直接带隙宽度随着应力的增大而减小;临界带隙双轴张应变Ge_(1-x)Sn_x具有极高的电子迁移率,空穴迁移率在较小应力作用下即可显著提升.考虑工艺实现难度和材料性能两个方面,可以选择4%Sn组分与1.2 GPa双轴张应力或3%Sn组分与1.5 GPa双轴张应力的组合用于高速器件和光电器件的设计.     

单轴应变Si(001)任意晶向电子电导有效质量模型

单轴应变Si材料电子电导有效质量是理解其电子迁移率增强的关键因素之一, 对其深入研究具有重要的理论意义和实用价值. 本文从Schrödinger方程出发, 将应力场考虑进来, 建立了单轴应变Si材料导带E-k解析模型. 并在此基础上, 最终建立了单轴应变Si(001)任意晶向电子电导率有效质量与应力强度和应力类型的关系模型. 本文的研究结果表明: 1) 单轴应力致电子迁移率增强的应力类型应选择张应力. 2) 单轴张应力情况下, 仅从电子电导有效质量角度考虑, [110]/(001)晶向与[100]/(001)晶向均可. 但考虑到态密度有效质量的因素, 应选择[110]/(001)晶向. 3) 沿(001)晶面上[110]晶向施加单轴张应力时, 若想进一步提高电子迁移率, 应选取[100]晶向为器件沟道方向. 以上结论可为应变Si nMOS器件性能增强的研究及导电沟道的应力与晶向设计提供重要理论依据. 关键词： 单轴应变 E-k关系')" href="#">E-k关系 电导有效质量     

Numerical study on optical and electrical properties of strained GaInSb/GaInAlSb mid-infrared quantum well laser

The optical and electrical properties of compressively strained GaInSb/GaInAlSb mid-infrared quantum well lasers are numerically studied solving one-dimensional Schrödinger equation using finite difference method. The simulation results demonstrate that band-mixing effects and effective mass of hole are reduced when the well is compressively strained. The strain-dependent optical and differential gains are evaluated for 0.6, 0.9, 1.21, and 1.52% compressively strained quantum well and found maximum when well is strained by 1.52%. The emission wavelength for the proposed laser can be tuned from 2.40 to 2.26 μm due to change in compressive strain from 0.60 to 1.52% at temperature 300 K. For the range of strain, the shift in wavelength is found from 2.38 to 2.24 μm at temperature 275 K. The results obtained from PSPICE simulation indicate that, the optical output power and threshold current are strongly depend on the number of wells and found to be almost constant for the number of wells three and above.