GaAs半导体表面的S-N混合等离子体钝化及在激光器工艺上的应用

利用射频(RF)等离子方法,对GaAs半导体表面进行 了S-N混合等离子体钝化实验,并对工作压强、RF 功率进行了优化。光致发光(PL)测试结果表明,经过S-N混合等离子体钝化的GaAs样品PL 强度提高135%。将本文 钝化方法应用到980nm波长InGaAs应变量子阱(QW)激光器的制备工艺 ,器件的COD阈值功率明显增加。     

半导体激光器面面观

量子阱(QW)激光器 (1)QW激光器 随着金属有机物化学汽相淀积(MOCVD)技术的逐渐成熟和完善,QW激光器很快从实验室研制进入商用化。QW器件是指采用QW材料作为有源区的光电子器件,材料生长一般     

低阈值高效率InAlGaAs量子阱808 nm激光器

以Al0.3Ga0.7As/InAlGaAs/Al0.3Ga0.7As压应变量子阱代替传统的无应变量子阱作为有源区,实现降低808 nm半导体激光器的阈值电流,并提高器件的效率。首先优化设计了器件结构,并利用金属有机物化学气相淀积(MOCVD)进行了器件的外延生长。通过优化外延生长条件,保证了5.08 cm片内的量子阱(QW)光致发光(PL)光谱峰值波长均匀性达0.1%。对于条宽为50μm,腔长为750μm的器件,经镀膜后的阈值电流为81mA,斜率效率为1.22 W/A,功率转换效率达53.7%。变腔长实验得到器件的腔损耗仅为2 cm-1,内量子效率达90%。结果表明,压应变量子阱半导体激光器具有更优异的特性。     

脊形InGaAs量子阱激光器的高频响应研究

对MBE生长的InGaAs 量子阱(QW)激光器的频率特性进行了研究.研制了InGaAs QW脊波导结构的激光器,通过控制脊的腐蚀深度,得到阈值电流密度为300 A/cm2的激光器,且激光器在常温下工作稳定,输出功率较大,其阈值电流附近3 dB带宽超过2 GHz.比较了不同电极面积时器件的调制响应,结果表明小面积电极可以有效提高器件的调制带宽.     

980nm大功率半导体激光器的MOCVD外延生长条件优化

为了对980 nm大功率半导体激光器的波导层和有源层外延材料进行快速表征,设计了相应的双异质结(DH)结构和量子阱(QW)结构,并在不同条件下进行了MOCVD外延生长,通过室温荧光谱测试分析,得到Alo.1Ga0.9As波导层的最佳生长温度为675℃,InGaAs QW的最佳长温度为575℃.为了兼顾波导层需高温生长和QW层需低温生长的需求,提出在InGaAsQW附近引入Alo.1Gao.9As薄间隔层的变温停顿生长方法,通过优化间隔层的厚度,InGaAs QW在室温下的PL谱的峰值半高宽只有23 meV.基于优化的外延工艺参数,进行了980 nm大功率半导体激光器的外延生长,并制备了腔长4 mm、条宽95 μm的脊形器件.结果显示,在没有采取任何主动散热情况下,器件在30A注入电流下仍未出现腔面灾变损伤,输出功率达到23.6W.     

MOCVD生长1．06μm InGaAs／GaAs量子阱LDs

用低压MOCVD生长应变InGaAs/GaAs量子阱,采用中断生长、应变缓冲层(SBL)、改变生长速度和调节Ⅴ/Ⅲ等方法改善InGaAs/GaAs量子阱的光致发光(PL)质量。PL结果表明,10s生长中断结合适当的SBL生长的量子阱PL谱较好。该量子阱应用于1.06μm激光器的制备,未镀膜的宽条激光器(100μm×1000μm)有低阈值电流密度(110A/cm2)和高的斜率效率(0.256W/A,per.facet)。     

Al薄膜对(002)ZnO/Al/Si结构基片中ZnO薄膜特性影响的实验研究

采用射频磁控溅射法沉积制备了(002)ZnO/A l/Si复合结构。研究了Al薄膜对(002) ZnO/Al/Si复合结构的声表面波器件(SAWD)基片性能影响以及当ZnO 薄膜厚度一定时的Al膜最佳厚度。采用X射线衍射(XRD)对Al和ZnO薄膜进行了结构表征 ,采用 扫描电镜(SEM)对ZnO薄膜进行表面形貌表征,并从薄膜生长机理角度进行了分析。结果 表明,加Al薄膜有利于ZnO薄膜按(002)择优取向生长,并且ZnO 薄膜的结晶性能提高;与(002)ZnO/Si结构基片相比,当Al薄膜 厚为100nm时,(002)ZnO/Al/Si结构中ZnO薄 膜的机电耦合系数提高 了65%。     

碳纤维强化聚合物封装的FBG传感器制备与特性试验

采用碳纤维强化聚合物(CFRP)对光纤Bragg光栅(FBG)进行封装,研制出用于测量混凝土内部应变的FBG应变传感器,分析了传感器轴向应变分布与结构参数的关系.通过在等强度梁和霍普金森压杆(SHPB)上的试验,得到了FBG传感器的静态性能指标和动态响应特性,结果表明,FBG应变传感器线性度≤1%,埋入混凝土结构内的F...     

以聚乙烯亚胺作为电子注入层的聚合物发光器件特性研究

在传统结构与倒置结构的有机发光二极管(LED)的聚合物发光层和阴极之间加入聚乙烯亚胺(PEIE)层能够显著地提高器件的发光效率。通过采用不同厚度的PEIE层的器件发光特性研究表明:PEIE层作为电子注入层(EIL)/空穴阻挡层(HBL)来平衡器件中的电子和空穴浓度,这主要来源于PEIE作为界面偶极层,能有效地降低阴极与发光层之间的电子注入势垒。     

850nm垂直腔面发射激光器结构优化与制备

根据分布布拉格反射镜(DBR)的工作原理,优化量子阱(QW)和DBR结构,采用Crosslight计算机模拟软件模拟了垂直腔面发射半导体激光器(VCSEL)的反射谱和QW增益谱,确定QW组分、厚度以及DBR的对数。采用分子束外延技术外延生长并制备了850nm顶发射VCSEL。测试结果表明,阱宽为5nm的In_(0.075)Ga_(0.925)As/Al_(0.35)Ga_(0.65)As QW,在室温下激射波长在840nm左右,设计的顶发射VCSEL结构通过Ocean Optics Spectra Suite软件验证,得到室温下的光谱中心波长在850nm附近,证实了结构设计的正确性。     

High-performance strain-compensated InGaAs-GaAsP-GaAs(λ=1.17 μm) quantum well diode lasers

This letter reports studies on highly strained and strain-compensated InGaAs quantum-well (QW) active diode lasers on GaAs substrates, fabricated by low-temperature (550°C) metal-organic chemical vapor deposition (MOCVD) growth. Strain compensation of the (compressively strained) InGaAs QW is investigated by using either InGaP (tensile-strained) cladding layer or GaAsP (tensile-strained) barrier layers. High-performance λ=1.165 μm laser emission is achieved from InGaAs-GaAsP strain-compensated QW laser structures, with threshold current densities of 65 A/cm² for 1500-μm-cavity devices and transparency current densities of 50 A/cm². The use of GaAsP-barrier layers are also shown to significantly improve the internal quantum efficiency of the highly strained InGaAs-active laser structure. As a result, external differential quantum efficiencies of 56% are achieved for 500-μm-cavity length diode lasers     

高效率GaAsP/AlGaAs张应变量子阱激光二极管

从理论上设计优化了高效率808 nm GaAsP/AlGaAs张应变量子阱激光二极管外延材料的量子阱结构和波导结构参数,并采用低压金属有机气相外延技术实验制备了外延材料.将制作的芯片解理成不同腔长,测试得到外延材料的内损耗系数和内量子效率分别为0.82 cm-1和93.6 %.把腔长为900 μm的单巴条芯片封装在热传...     

量子阱材料盖层对结构稳定性和能带隙的影响

介绍了应变量阱材料单结点失配位错能量平衡模型,计算了一些典型量子阱 阱层临界应变和应变体材料的最大允许应变。报告了Ｎｏ．５５８压应变量子阱材料的实际阱层应变和Ｎｏ．９１８２材料非应变盖层对有源层泊影响。     

Linewidth enhancement factor in strained quantum well lasers

The linewidth enhancement factor α of strained quantum-well lasers is analyzed by the k-p perturbation method using the effective-mass approximation. It is found that the α factor in a strained In_0.80Ga_0.20As/InP quantum-well (QW) laser with 1.9% biaxial compression is less than 1.5. For a strained QW laser with p-type modulation doping (MD) of 5×10 ¹⁸ cm^-3, the α factor is as small as 0.8. It is also demonstrated that the spectral linewidth and wavelength chirping in the strained MD QW laser are significantly less than those in conventional bulk and QW lasers     

Threshold current density reduction of strained AlInGaAs quantum-well laser

In the last decades, researchers have tried to implement novel optoelectronic devices with new semiconductor material compounds. There are few competitors in the race for more reliable, more efficient, pump sources for solid-state lasers. These diodes should operate at high power, intense brightness, and with low threshold current. The strained AlInGaAs-GaAs quantum-well (QW) laser is a promising candidate. In this study we optimized the growth parameters of strained AlInGaAs quantum wells using a model for linewidth broadening of photoluminescence, which was extended for the first time to handle quaternary alloys. This model enables us to identify the dominant contributions to the broadening. As a result of our growth parameters optimization technique, low threshold current density of simple broad-area lasers has been obtained, indicating a superior material quality. Moreover, we have studied for the first time the effect of indium and aluminum content and QW width on the threshold current density of quaternary AlInGaAs QW lasers. As a result of these studies the lowest known threshold current density for AlInGaAs on GaAs single QW broad-area laser has been achieved.     

InGaN/GaN quantum well growth on pyramids of epitaxial lateral overgrown GaN

InGaN/GaN quantum wells (QW) were grown by metalorganic chemical vapor deposition (MOCVD) on pyramids of epitaxial lateral overgrown (ELO) GaN samples. The ELO GaN samples were grown by MOCVD on sapphire (0001) substrates that were patterned with a SiN_x mask. Scanning electron microscopy and cathodoluminescence (CL) imaging experiments were performed to examine lateral variations in structure and QW luminescence energy. CL wavelength imaging (CLWI) measurements show that the QW peaks on the top of the grooves are red-shifted in comparison with the QW emission from the side walls. The results show that In atoms have migrated to the top of the pyramids during the QW growth. The effects of V/III ratio, growth temperature as well as ELO GaN stripe orientation on the QW properties are also studied.     

Dependence of linewidth enhancement factor on crystal orientationin strained quantum well lasers

The linewidth enhancement factor a in strained quantum well (QW) lasers is estimated theoretically for various crystallographic directions. It is found that the a factor in a strained In_0.7Ga_0.3As-InP QW laser on a (111) substrate is less than 1.4, much lower than for conventional strained QW lasers on (001) substrates     

Reduction of noise figure in semiconductor laser amplifiers with Ga1-xInxAs/GaInAsP/InP strained quantum wellstructures

The noise characteristics of semiconductor laser amplifiers (SLAs) in the Ga_1-xIn_xAs/GaInAsP/InP strained quantum well (QW) system are theoretically calculated and analyzed using density-matrix theory and taking into account the effects of band mixing on both the valence subbands and the transition dipole moments. The numerical results show that a reduced noise figure can be obtained in both tensile and compressively strained QW structures due to the increase in differential gain and the decrease in transparent carrier density. From a comparison among compressively strained (x=0.70), unstrained (x=0.53), and tensile strained (x=0.40) QW SLAs at a fixed carrier density and optical confinement factor, it is found that the noise figure of the tensile strained QW reaches its lowest value of 3.4 dB at average input optical power of -20 dB     

An 850-nm InAlGaAs strained quantum-well vertical-cavitysurface-emitting laser grown on GaAs (311)B substrate withhigh-polarization stability

The polarization stability of 850-nm InAlGaAs strained quantum-well (QW) vertical-cavity surface-emitting laser (VCSEL) grown on GaAs (311)B substrate was investigated by comparing it with that of GaAs unstrained QW VCSEL grown on GaAs (311)B substrate. Photoluminescence measurement showed that strained QWs grown on GaAs (311)B substrate had larger anisotropy in optical gain than unstrained QWs. The VCSEL with strained QWs showed an orthogonal polarization suppression ratio (OPSR) as high as 21 dB under CW operation. Time-dependent OPSR measurement indicated that the strained QW VCSEL had higher polarization stability than the unstrained QW VCSEL under zero-bias modulation     

1.5< lambda <1.7 mu m strained multiquantum well InGaAs/InGaAsP diode lasers

The long wavelength limitations of strained In/sub 0.7/Ga/sub 0.3/As/InGaAsP four-quantum well (QW) lasers are investigated. For this confining structure and QW composition, wavelengths range from 1.52 to 1.72 mu m for QW thicknesses between 33 and 70 AA, and there is an optimum QW thickness of approximately 40 AA.<>