Si(001)衬底上分子束外延生长Ge0.975Sn0.025合金薄膜

使用低、高温两步法生长的高质量Ge薄膜作为缓冲层,在Si(001)衬底上采用分子束外延法生长出Ge_0.975Sn_0.025合金薄膜.X射线双晶衍射和卢瑟福背散射谱等测试结果表明,Ge_0.975Sn_0.025合金薄膜具有很好的晶体质量,并且没有发生Sn表面分凝.另外,Ge_0.975Sn_0.025合金薄膜在500 ℃下具有很好的热稳定性,有望在Si基光电器件中得到应用. 关键词： GeSn Ge 分子束外延 外延生长     

A comparison of silicon oxide and nitride as host matrices on the photoluminescence from Er+ ions

This paper compares the properties of silicon oxide and nitride as host matrices for Er ions.Erbium-doped silicon nitride films were deposited by a plasma-enhanced chemical-vapour deposition system.After deposition,the films were implanted with Er3+ at different doses.Er-doped thermal grown silicon oxide films were prepared at the same time as references.Photoluminescence features of Er3+ were inspected systematically.It is found that silicon nitride films are suitable for high concentration doping and the thermal quenching effect is not severe.However,a very high annealing temperature up to 1200° C is needed to optically activate Er3+,which may be the main obstacle to impede the application of Er-doped silicon nitride.     

Sixteen-element Ge-on-SOI PIN photo-detector arrays for parallel optical interconnects

We describe the structure and testing of one-dimensional array parallel-optics photo-detectors with 16 photodiodes of which each diode operates up to 8 Gb/s. The single element is vertical and top illuminated 30μm-diameter silicon on insulator （Ge-on-SOI） PIN photodetector. High-quality Ge absorption layer is epitaxially grown on SO1 substrate by the ultra-high vacuum chemical vapor deposition （UHV-CVD）. The photodiode exhibits a good responsivity of 0.20 A/W at a wavelength of 1550 nm. The dark current is as low as 0.36/aA at a reverse bias of 1 V, and the corresponding current density is about 51 mA/cm2. The detector with a diameter of 30 t.trn is measured at an incident light of 1.55 μm and 0.5 mW, and the 3-dB bandwidth is 7.39 GHz without bias and 13.9 GHz at a reverse bias of 3 V. The 16 devices show a good consistency.     

基于Franz-Keldysh效应的倏逝波锗硅电吸收调制器设计

本文设计了一种基于Franz-Keldysh (FK) 效应的GeSi电吸收调制器. 调制器集成了脊形硅单模波导. 光由脊形硅波导以倏逝波形式耦合进锗硅吸收层. 在硅基锗二极管FK效应实验测试的基础上, 有源区调制层锗硅中的硅组分设计为1.19%, 从而使得器件工作在C (1528–1560 nm) 波段. 模拟结果显示该调制器的3 dB带宽可达64 GHz, 消光比为8.8 dB, 而插损仅为2.7 dB. 关键词： 锗硅 调制器 电光集成     

带隙法测定SiGe/Si材料的应变状态

从固体模型理论的结果出发，计算了生长于Si（100）衬底上x值小于085的Si_1-xGe_x合金材料（能带结构为类Si结构）的间接带隙与应变的关系，结 果表明，应变的S iGe材料的带隙和完全弛豫状态下材料的带隙之差与应变呈线性关系.基于这一结果，提出了 用测量带隙来间接测定SiGe/Si应变状态的方法.用带隙法和x射线双晶衍射法测量了不同应 变状态下的SiGe/Si多量子阱材料的应变弛豫度，两者可以较好的符合，表明带隙法测量SiG e应变弛豫度是可行的. 关键词： SiGe合金 应变 带隙     

Room-temperature direct-bandgap photoluminescence from strain-compensated Ge/SiGe multiple quantum wells on silicon

Strain-compensated Ge/Si_0.15Ge_0.85 multiple quantum wells were grown on an Si_0.1>Ge_0.9 virtual substrate using ultrahigh vacuum chemical vapor deposition technology on an n⁺-Si(001) substrate. Photoluminescence measurements were performed at room temperature, and the quantum confinement effect of the direct-bandgap transitions of a Ge quantum well was observed, which is in good agreement with the calculated results. The luminescence mechanism was discussed by recombination rate analysis and the temperature dependence of the luminescence spectrum.     

High bandwidth surface-illuminated InGaAs/InP uni-travelling-carrier photodetector

Uni-traveling-carrier photodiodes(UTC-PDs)with ultrafast response and high saturation output are reported.A gradient doping layer and a narrow InP cliff layer were introduced to enhance the saturation and bandwidth characteristics.We measured the dark current,photo response,bandwidth,and saturation current of the fabricated UTC devices.For a15-μm-diameter device,the dark current was 3.5 nA at a reverse bias of 1 V,and the 3-dB bandwidth was 17.2 GHz at a reverse bias of 5 V,which are comparable to the theoretically values.The maximum responsivity at 1.55μm was 0.32 A/W.The saturation output current was over 19.0 mA without bias.     

Efficient evanescent coupling design for GeSi electro-absorption modulator

Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for increasing the modulating efficiency and alleviating the sensitivity of the extinction ratio （ER） and insertion loss （IL） to the length of the active region. The light behavior and the effect of the taper are explored in detail using the beam propagation method （BPM）. After optimization, the light can nearly be totally confined in the GeSi layer without any oscillation. The modulator with the designed taper can achieve low IL and high ER.     

掺杂对多层Ge/Si(001)量子点光致发光的影响

利用超高真空化学气相沉积设备, 在Si (001) 衬底上外延生长了多个四层Ge/Si量子点样品. 通过原位掺杂的方法, 对不同样品中的Ge/Si量子点分别进行了未掺杂、磷掺杂和硼掺杂. 相比未掺杂的样品, 磷掺杂不影响Ge/Si量子点的表面形貌, 但可以有效增强其室温光致发光; 而硼掺杂会增强Ge/Si量子点的合并, 降低小尺寸Ge/Si量子点的密度, 但其光致发光会减弱. 磷掺杂增强Ge/Si量子点光致发光的原因是, 磷掺杂为Ge/Si量子点提供了更多参与辐射复合的电子. 关键词： Ge/Si量子点 磷掺杂 光致发光     

单行载流子光电探测器中空间电荷屏蔽效应理论分析和实验研究

本文优化设计和外延生长了一种单行载流子(UTC)光电探测器有源区结构,并且采用微电子工艺制备了台面尺寸为30μm的UTC光电探测器.同时,采用了漂移-扩散模型对该有源区结构进行了理论模拟,从载流子浓度和空间电场角度重点分析研究了空间电荷屏蔽效应对UTC光电探测器直流饱和特性影响的物理机理.UTC光电探测器理论模拟结果与实测数据基本相符.