Wide-Band Polarization-Independent Semiconductor Optical Amplifier Gate with Tensile-Strained Quasi-Bulk InGaAs

A semiconductor optical amplifier gate based on tensile-strained quasi-bulk InGaAs is developed. At injection current of 80mA,a 3dB optical bandwidth of more than 85nm is achieved due to dominant band-filling effect.Moreover, the most important is that very low polarization dependence of gain (＜0. 7dB),fiber-to-fiber lossless operation current (70～90mA) and a high extinction ratio (＞50dB) are simultaneously obtained over this wide 3dB optical bandwidth (1520～1609nm) which nearly covers the spectral region of the whole C band (1525～1565nm)and the whole L band (1570～ 1610nm). The gating time is also improved by decreasing carrier lifetime. The wideband polarization-insensitive SOA-gate is promising for use in future dense wavelength division multiplexing (DWDM) communication systems.

掺杂InGaAs/InAlAs单量子阱中电子对称态和反对称态磁输运研究

利用变温Hall测量研究了重掺杂InGaAs/InAlAs单量子阱中二维电子气,发现在量子阱中由于存在电子对称态和反对称态导致纵向电阻出现拍频现象.通过分析拍频节点位置,得到电子对称态和反对称态之间的能级间距为4meV.此外,通过迁移率谱方法和多载流子拟合过程研究了不同迁移率电子的浓度和迁移率随温度的变化关系.

1.78 μm Strained InGaAs-InGaAsP-InP Distributed Feedback Quantum Well Lasers

Ridge-waveguide distributed-feedback(DFB) lasers with highly strained InGaAs/InGaAsP active regions,emitting at 1.78 μm were fabricated by low pressure metal-organic vapor phase epitaxy(LP-MOVPE) and tested.The lasers exhibited threshold current of 33 mA for 900 μm long cavities at room temperature.A maximum light output power of 8 mW from one facet and an external differential quantum efficiency of 7% were also obtained.In oddition,the side mode suppression ratio (SMSR) is 27.5 dB.

高增益偏振不灵敏InGaAs/InP体材料半导体光放大器

采用三元InGaAs体材料为有源区,通过直接在InGaAs体材料中引入0.20%张应变来加强TM模的增益,研制了一种适合于作波长变换器的偏振不灵敏半导体光放大器(SOA).在低压金属有机化学气相外延(LP-MOVPE)的过程中,只需调节三甲基Ga的源流量便可获得所要求的张应变量.制作的半导体光放大器在200 mA的注入电流下,获得了50nm宽的3 dB光带宽和小于0.5dB的增益抖动;重要的是,半导体光放大器能在较大的电流和波长范围里实现小于1.1dB的偏振灵敏度.对于1.55μm波长的信号光,在200 mA的偏置下,其偏振灵敏度小于1 dB,同时获得了大于14dB光纤到光纤的增益,3 dBm的饱和输出功率和大于30 dB的芯片增益.用作波长变换器,可获得较高的波长变换效率.进一步提高半导体光放大器与光纤的耦合效率,可得到性能更佳的半导体光放大器.

变In组分沟道的MM-HEMT材料电子输运特性研究

在变缓冲层高迁移率晶体管(MM-HEMT)器件中,二维电子气的输运性质对器件性能起着决定作用.通过低温下二维电子气横向电阻的量子振荡现象,结合变温度的Hall测量,系统研究了不同In组分沟道MM-HEMT器件中子带电子迁移率和浓度随温度的变化关系.结果表明,沟道中In组分为0.65的样品,材料电学性能最好,In组分高于0.65的样品,严重的晶格失配将产生位错,引起迁移率下降,大大影响材料和器件的性能.

具有InAlAs浸润层的InGaAs量子点的制备和特性研究

采用自组装方法生长了一种新型的InGaAs量子点/InAlAs浸润层结构.通过选取合适的In组分,使InAlAs浸润层的能级与GaAs势垒相当,从而使浸润层的量子阱特征消失.通过低温光致发光(PL)谱的测试分析得到InGaAs量子点/InAlAs浸润层在样品中的确切位置.变温PL谱的研究显示,具有这种结构的量子点发光峰的半高全宽随温度上升出现展宽,这明显区别于普通InGaAs量子点半高全宽变窄的行为.这是因为采用了InAlAs浸润层后,不仅增强了对InGaAs量子点的限制作用,同时切断了载流子的转移通道,使得量子点更加孤立后表现出来的性质.

MBE生长的跨导为186 mS/mm的AlGaN/GaN HEMT

用分子束外延(MBE)技术研制出了AlGaN/GaN高电子迁移率晶体管(HEMT)材料,其室温迁移率为1 035 cm2/Vs、二维电子气浓度为1.0×1013 cm-2;77 K迁移率为2 653 cm2/V*s、二维电子气浓度为9.6×1012 cm-2.用此材料研制了栅长为1 μm、栅宽为80 μm、源-漏间距为4 μm的AlGaN/GaN HEMT,其室温最大非本征跨导为186 mS/mm、最大漏极饱和电流密度为925 mA/mm、特征频率为18.8 GHz.另外,还研制了具有20个栅指(总栅宽为20×80 μm＝1.6 mm)的大尺寸器件,该器件的最大漏极饱和电流为1.33 A.

Optimization of InGaAs Quantum Dots for Optoelectronic Applications

Self-assembled In_0.35Ga_0.65As/GaAs quantum dots with low indium content are grown under different growth temperature and investigated using contact atomic force microscopy(AFM). In order to obtain high density and high uniformityu of quantum dots, optimized conditions are concluded for MBE growth. Optimized growth condi-tions also compared with these of InAs/GaAs quantum dots. This will be very useful for InGaAs/GaAs QDs opto-electronic applications, such as quantum dots lasers and quantum dots infrared photodetectors.

快速热处理对应变InGaAs/GaAs单量子阱激光二极管电子发射和DX中心的影响

研究分子束外延（MBE）生长的应变In_(0.2)Ga_(0.8)As/GaAs折射率梯度变化异质结单量子阱激光二极管的快速热处理（RTA）效应。结果表明，RTA移除了InCaAs/GaAs界面非辐射中心，提高77K光致发光效率和有源层电子发射。同时Al和Ga原子互扩散，也增加了AlGaAs波导层DX中心浓度。RTA处理后样品电流冲击老化实验证明DX中心浓度呈现出相应的增加。这表明DX中心可能是激光二极管性能退化的原因之一。

A Single Mode 980nm InGaAs/GaAs/AlGaAs Large Optical Cavity Quantum Well Laser with Low Vertical Divergence Angle

To achieve high optical power as well as low vertical divergence angle, a new kind of optimized large optical cavity (LOC) structure is applied to a ridge waveguide 980nm InGaAs/GaAs/AlGaAs multi-quantum well laser. The optical power density in the waveguide is successfully reduced. The maximum output power is more than 400mW with a slope efficiency of 0.89W/A and the far-field vertical divergence angle is lowered to 23°.

InGaAs/GaAs/AlGaAs应变量子阱激光器

优化设计了既能实现较小垂直方向远场发散角，又能降低腔面光功率密度的InGaAs/GaAs/AlGaAs应变层量子阱激光器，并计算了该结构激光器实现基横模工作的脊形波导结构参数。利用分子束外延生长了InGaAs/GaAs/AlGaAs应变量子阱激光器材料并研制出基横模输出功率大于140mW，激射波长为980nm的脊形波导应变量子阱激光器，其微分量子效率为0.8W/A，垂直和平行结平面方向远场发散角分别为28°和6.8°。

InGaAs/InAlAs量子级联激光器研究

简要报道了自行研制的InGaAs/InAlAs量子级联激光器的制备及其主要特性。该器件具有增强型脊型波导结构，在80K时阈值电流为0.5A，相应的阈值电流密度为5KA/cm~2。

InGaAs/GaAs自组织量子点光致发光特性研究

用PL谱测试研究了GaAs和不同In组份In_xGa_(1-x)As(x=0.1,0.2,0.3)覆盖层对分子束外延生长的InAs/GaAs自组织量子点发光特性的影响。用In_xGa_(1-x)As外延层覆盖InAs/GaAs量子点，比用GaAs做覆盖层其发光峰能量向低能端移动，发光峰半高宽变窄，量子点发光峰能量随温度的红移幅度变小。理论计算证实这是由于覆盖层In_xGa_(1-x)As减小了InAs表面应力导致发光峰红移，而In元素有效抑制了InAs/GaAs界面组份的混杂，量子点的均匀性得到改善，PL谱谱半高宽变窄。用InGaAs覆盖的In_(0.5)Ga_(0.5)As/GaAs自组织量子点实现了1.3μm发光，室温下PL谱半高宽为19.2meV，是目前最好的实验结果。

InGaAs/InP中离子注入和新型HPT

北京市基金,国家自然科学基金