超低压选择区域生长法制备产生10GHz重复率超短光脉冲的级联电吸收调制器与分布反馈激光器单片集成光源

采用超低压(22×１０^２Pa)选择区域生长(selective area growth, SAG)金属有机化学气相沉积(metal-organic chemical vapor deposition, MOCVD)技术成功制备了InGaAsP/InGaAsP 级联电吸收调制器(electroabsorption modulator, EAM)与分布反馈激光器(distributed feedback laser, DFB)单片集成光源的新型光电器件.实验结果表明，采用该技术制备的器件 关键词： 超低压 选择区域生长 集成光电子器件 超短光脉冲     

用于10Gb/s传输系统的电吸收调制器与分布反馈激光器集成光源

采用超低压(22×１０^２Pa)选择区域生长(selective area growth, SAG)金属有机化学气相沉积(metal-organic chemical vapor deposition, MOCVD)技术成功制备了应变型InGaAsP/InGaAsP电吸收调制器(electroabsorption modulator, EAM)与分布反馈激光器(distribute feedback laser, DFB)单片集成光源的新型光电器件.实验结果表明，采用该技术制备的集成器件表现出了良好的性能：激射阈值为19 mA，出光功率接近7 mW，边模抑制比(side-mode suppression ratio, SMSR)大于40 dB，将该集成器件出射光耦合进普通单模光纤后进行测量，获得了16 dB的消光比，器件3 dB响应带宽达到了10 GHz以上.将该集成器件完全封装后成功进行了10 Gb/s非归零码(non-return zero, NRZ)的传输实验：在误码率为10^-10的传输条件下于普通单模光纤中传输了53.3 km，色散代价小于1.5 dB，动态消光比大于8 dB，且眼图清晰张开. 关键词： 超低压 选择区域生长 集成光电子器件 10 Gb/s     

InGaAsP分别限制量子阱激光器

长波长InGaAsP量子阱激光器,以其低阈值、窄光谱线宽和高的调制频带宽等优良特性而成为大容量通信的基础。为此,我们利用低压MOVCD技术生长了1.62μm和1.3μm的InGaAsP材料,测得其77K光荧光(PL)谱线半峰高宽分别为18.7meV和28meV.利用X射线双晶衍射测得两种材料的晶格失配度不大于1×10^-3.并生长了四个不同阱宽的InGaAsP/InP量子阱结构,测得77K温度下的PL谱,分析了阱宽对发光波长及半峰宽的影响,并提出在量子阱激光器中减小界面层影响的方法。在此基础上,生长了分别限制量子阱激光器结构,并利用质子轰击制备出条形结构激光器,测得其最低阈值电流为100mA.直流工作光谱峰值波长为1.52μm左右,单面输出外微分量子效率约为36%.     

长波长大应变InGaAs/InGaAsP分布反馈激光器的材料生长与器件制备

采用低压金属有机化合物气相沉积法(LP-MOCVD)生长并制作了1.6—1.7μm大应变InGaAs/InGaAsP分布反馈激光器.采用应变缓冲层技术，得到质量良好的大应变InGaAs/InP体材料.器件采用了4个大应变的量子阱，加入了载流子阻挡层改善器件的温度特性.1.66μm和1.74μm未镀膜的3μm脊型波导器件阈值电流低(小于15mA)，输出功率高(100mA时大于14mW).从10—40℃，1.74μm激光器的特征温度T₀=57K，和1.55μm InGaAsP分布反馈激光器的特征温度相当. 关键词： MOCVD InGaAs/InGaAsP 应变量子阱 分布反馈激光器     

InGaAs/GaAs应变量子阱的发光特性研究

利用低压金属有机化学气相沉积技术(LP-MOCVD)生长InGaAs/GaAs单量子阱(SQW),通过改变生长速率、优化生长温度和V/III比改善了量子阱样品的室温光致发光(PL)特性。测试结果表明,当生长温度为600℃、生长速率为1.15μm/h时,生长的量子阱PL谱较好,增加V/III比能够提高量子阱的发光强度。实验分析了在不同的In气相比条件下,生长速率对量子阱质量的影响,利用模型解释了高In气相比时,随着生长速率增加PL谱蓝移现象消失的原因。     

1.3μm InGaAsP/InP双异质结发光管的特性研究

用液相外延技术生长的三层和四层InGaAsP/InP双异质结材料,制成了1.3μm InGaAsP/InP双异质结发光管。光功率输出(100mA)>1.0mW,最高2mW,尾纤输出功率(N.A.0.23,芯径60μ)>50μW。文中描述了器件的特性参数,还讨论了光功率的饱和特性和退化特性。     

调制掺杂ZnSe/BeTe Ⅱ型量子阱结构中的内秉电场和新型带电激子

报道了调制掺杂的ZnSe/BeTe/ZnSe Ⅱ型量子阱(type-Ⅱ QW)在低温(2—5 K)条件下的光致发光(PL)，光致发光激发(PLE)和磁性光致发光(magneto-PL)光谱的实验结果.　观察到非掺杂样品的PL有两个很强的主发光峰而掺杂样品只有一个的奇异发光.　PL直线偏振度和PLE的测量结果都表明了这些空间间接型跃迁PL是来自两个异质结界面的贡献，非掺杂样品的两个主发光峰的分离则是起因于QW结构中的内秉电场(built-in electric field).在平行于QW生长方向的强磁场中， 关键词： 光致发光 二维电子气 带电激子 Ⅱ型量子阱     

Si1-xCex/Si量子阱发光材料制备及特性研究

在si(100)衬底上用分子束外延成功生长了Si_(1-x)Ge_x/si量子阱发光材料,发现在生长过程中背景杂质含量直接影响材料的发光特性,用光致发光(PL)和卢瑟福背散射(RBS)对样品质量进行标定。在PL测量中观察到合金量子阱带边激子分辨峰,并对发光峰能和峰宽作了讨论。 关键词：     

InxGa1-xN/InyGa1-yN多量子阱结构 发光特性的测量与分析

利用MOCVD方法在蓝宝石衬底上生长了In_xGa_1-xN/In_yGa_1-yN多量子阱结构外延层,并用变温光致发光(PL)光谱、选择激发光谱以及激发(PLE)光谱等手段研究了该结构的量子效率、多峰效应的起源以及峰位随温度变化等信息。变温PL光谱的结果表明:在温度从30 K变化到300 K时,其峰值强度只下降了1.36倍且发光波长发生了蓝移。通过选择激发光谱证明了其发光峰位的独立性。PLE结果表明了GaN和势垒层的Stokes位移很小,但是In_xGa_1-xN阱层的Stokes位移变化很大。同时,提出了一种可同时获得多个吸收边的数据处理方法。     

InGaN/GaN多量子阱的组分确定和晶格常数计算

采用金属有机化学气相沉积(MOCVD)技术以蓝宝石为衬底在n型GaN单晶层上生长了InGaN/GaN多量子阱结构外延薄膜，利用高分辨X射线衍射(HRXRD)，卢瑟福背散射/沟道(RBS/channeling)，以及光致发光(PL)技术对InGaN/GaN多量子阱结构薄膜分别进行了平均晶格常数计算、In原子替位率计算和In组分的定量分析.研究表明：InGaN/GaN多量子阱的水平和垂直方向平均晶格常数分别为a_epi=0.3195nm，c_epi=0.5198nm，In原子的替位率为99.3%，利用HRXRD和RBS/channeling两种分析技术计算In的组分分别是0.023和0.026，并与样品生长时设定的预期目标相符合，验证了两种实验方法的准确性；而用室温条件下的光致发光谱(PL)来计算InGaN/GaN多量子阱中In的组分是与HRXRD和RBS/channeling的实验结果相差很大，说明用PL测试In组分的方法是不适宜的. 关键词： InGaN/GaN多量子阱 高分辨X射线衍射 卢瑟福背散射/沟道 光致发光     

Experimental and theoretical investigations of optical properties of GaN/AlGaN MQW nanostructures. Impact of built-in polarization fields

We report the results from detailed optical spectroscopy from MOCVD grown GaN/AlGaN multiple quantum wells (MQWs), as opposed to most previous studies where MBE was employed by means of photoluminescence (PL) technique. In this paper we will present theoretical and experimental results demonstrating how polarization induced electric fields and bound interface charges in GaN/AlGaN MQWs affect the emission peak energy, PL line shape, as well as the emission line width. Theoretically estimated fields in this work are consistent with experimental data. Transition energy of the heavy hole and electron ground state Ee-hh in GaN/AlGaN MQWs were calculated and it is found that it stays in good agreement with the experimental data.     

利用选择性外延法生长单芯片双波长白光InGaN/GaN多量子阱结构

为了制备单芯片无荧光粉白光InGaN/GaN多量子阱发光结构,利用选择性外延生长法在SiO2条纹掩膜板上生长出具有梯形形貌的GaN微面结构,并在该GaN微面结构上生长InGaN/GaN多量子阱结构,最终在单芯片上获得了双波长发光.结果表明:梯形GaN微面由(0001)和(11-22)面组成,两者的表面能和极性不同,并且在InGaN/GaN多量子阱生长过程中,In原子和Ga原子迁移速率不同,从而使得(0001)和(11-22)面上的多量子阱具有不同的发光波长;该性质可以使(11-22)面的微面量子阱发出蓝光(峰值波长为420nm),而(0001)面的量子阱发出黄光(峰值波长为525nm),最终形成双波长的复合白光外延结构.     

Growth and characterization of strain-compensated InGaAs/GaAsSb type II multiple quantum wells on InP substrate

Strain-compensated InGaAs/GaAsSb type II multiple quantum wells (MQWs) were grown by molecular beam epitaxy (MBE) and their optical and electrical properties were studied. High-quality strain-compensated type II MQWs were successfully grown, which have longer emission wavelength than that of lattice-matched type II MQWs. PL peak energy at 300 K of the strain-compensated type II MQWs, where the InGaAs layer has 0.6% tensile strain and GaAsSb layer has 0.6% compressive strain, shows a red-shift of 43 meV, which is 12 meV larger than the calculated energy shift of 31 meV. In addition, the PL intensity and the electron mobility of the strain-compensated MQWs are comparable to those of the lattice-matched MQWs, suggesting that the crystal quality of the strain-compensated MQWs is good and are very promising for low dark current photodiodes in the 2 μm wavelength region.     

Quantum well intermixing of multiple quantum wells on InP by argon plasma bombardment and the sputtered-SiO2 film

A quantum well intermixing process combining inductively-coupled-plasma reactive ion etching (ICP-RIE) and SiO₂ sputtering film was investigated for the InGaAsP and InGaAlAs multi-quantum wells (MQWs). Optimal distance is 300-nm-thick for InGaAsP and of 200-nm-thick for InGaAlAs. Between MQWs and the upper cladding by ICP-RIE and bombardment, covering the 300-nm-thick sputtered SiO₂ using rapid thermal annealer (RTA) processing resulted in a band-gap blue-shift of 90 nm for InGaAsP and of 60 nm for InGaAlAs.     

Investigation of electron energy states in InGaN/GaN multiple quantum wells

Blue light emitting diodes (LED) consisting of InGaN/GaN multiple quantum wells (MQWs) have been grown by metal organic chemical vapor deposition (MOCVD) on sapphire. The width of the quantum wells (InGaN) was maintained in the range of 3–5 nm with a barrier of 10–15 nm of GaN. Various diagnostic techniques were employed for the characterization of the InGaN/GaN heterostructure. Carrier concentration depth profile from C–V measurements demonstrated the presence of MQWs. The higher value of built-in voltage (15 V) determined from C⁻²–V plot also supported the presence of MQWs as assumed to alter the space-charge region width and hence the intercept voltage. Arrhenius plots due to DLTS spectra from the device revealed at least four energy states (eV) 0.1, 0.12, 0.15 and 0.17, respectively in the quantum wells, with respect to the barrier. Further the photoluminescence spectrum showed an InGaN-based broad band centered at 2.9 eV and the GaN peak at 3.4 eV. A comparison of the PL spectrum with the literature helped to estimate the indium content in the QW (InGaN) and its width to be ∼13% and ∼3 nm, respectively. The results were consistent with the DLTS findings.     

多量子阱超辐射发光二极管(SLD)热分布计算

对由8个量子阱所组成的条形超辐射发光二极管(Super luminescent diode,SLD)进行了热分析,计算了不同器件结构下的热阻和温度分布。计算结果表明,热阻变化受芯片宽度和长度的影响较大,可以达到两个数量级;当注入功率达到1W时,有源区的温度将接近50K。该分析对有效地设计芯片的结构,减少温度升高对SLD稳定性的影响具有指导意义。     

Influence of holmium doping on the optical properties of quaternary InGaAsP epitaxial layers

Photoluminescence and photoconductivity measurements were used to study the influence of Ho doping on the optical properties of InGaAsP layers grown by liquid phase epitaxy (LPE). The full width at half maximum (FWHM) of the photoluminescence peak was found to decrease as the amount of Ho increases. When the amount of Ho is 0.11 wt%, the FWHM has a minimum value of 7.93 meV, about 46% lower than that of the undoped InGaAsP. The absorption tails observed in the photoconductivity were analyzed with the Urbach tail model and the Urbach energies were obtained from the fits. The Urbach energy decreases as the amount of Ho increases, indicating that Ho doping greatly reduces the amount of residual impurities in LPE-grown layers.     

无杂质空位扩散法造成InGaAsP/InP多量子阱结构带隙蓝移规律的研究

采用光荧光谱(PL)和光调制反射谱(PR)的方法,研究了由Si₃N₄、SiO₂电介质盖层引起的无杂质空位(IFVD)诱导的InGaAsP四元化合物半导体多量子阱(MQWs)结构的带隙蓝移。实验中Si₃N₄、SiO₂作为电介质盖层,用来产生空位,再经过快速热退火处理(RTA)。实验结果表明:多量子阱结构带隙蓝移和退火温度、复合盖层的组合有关。带隙蓝移随退火温度的升高而加大。InP、Si₃N₄复合盖层产生的带隙蓝移量大于InP、SiO₂复合盖层。而InGaAs、SiO₂复合盖层产生的带隙蓝移量则大于InGaAs、Si₃N₄复合盖层。同时,光调制反射谱的测试结果与光荧光测试的结果基本一致,因此,PR谱是用于测试带隙变化的另一种方法。     

纳米折叠InGaN/GaN LED材料生长及器件特性

在以自组织Ni纳米岛为掩膜制作的n-GaN纳米柱上,利用MOCVD方法外延生长了具有折叠InGaN/GaN多量子阱(MQW)的LED结构外延片,进而制作了LED器件.外延片上中下游的光致荧光测试,结果表明外延片具有很好的均匀性.用该外延片制作的LED的电致发光谱,随注入电流增加没有明显蓝移,这表明纳米结构能更好地释放应力,纳米柱上外延生长的多量子阱,具有较低的压电极化电场.正向工作电流20 mA时,LED器件的工作电压为4.6 V. 关键词： 纳米柱LED 光致发光 电致发光     

反应磁控溅射ZnO/MgO多量子阱的光致荧光光谱分析

采用反应射频磁控溅射方法，在Si(001)基片上制备了具有高c轴择优取向的ZnO/MgO多量子阱.利用X射线反射、X射线衍射、电子探针，光致荧光光谱等表征技术，研究了ZnO/MgO多量子阱的结构、成份和光致荧光特性.研究结果表明，多量子阱的调制周期在1.85—22.3 nm之间，所制备的多量子阱具有量子限域效应，导致了室温光致荧光峰的蓝移，并观测到了量子隧穿效应引起的荧光效率下降.建立了基于多声子辅助激子复合跃迁理论的室温光致荧光光谱优化拟合方法，通过室温光致荧光光谱拟合发现，ZnO/MgO比ZnO/ZnMgO多量子阱具有更大的峰位蓝移，探讨了导致光致荧光光谱展宽的可能因素. 关键词： ZnO/MgO 多量子阱 磁控溅射 光致荧光 量子限域效应