硅基MEMS技术

结合MEMS技术的发展历史 ,概括了当今硅基MEMS加工技术的发展方向。指出表面牺牲层技术和体硅加工技术是硅基MEMS加工技术的两条发展主线 ;表面牺牲层技术向多层、集成化方向发展 ;体硅工艺主要表现为键合与深刻蚀技术的组合 ,追求大质量块和低应力以及三维加工。SOI技术是新一代的体硅工艺发展方向 ;标准化加工是MEMS研究的重要手段

High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre

A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46% and 25% at a wavelength of 1.55 mu m are achieved by simulation and experiment, respectively. An optical 3 dB bandwidth of 45 nm from 1530 nm to 1575 nm is also obtained in experiment. Numerical calculation shows that a tolerance to fabrication error of 10 nm in etch depth is achievable. The measurement results indicate that the alignment error of +/-2 mu m results in less than 1 dB additional coupling loss.

Tuning of the two electron states in quantum rings through the spin-orbit interaction

The effect of the Coulomb interaction on the energy spectrum and anisotropic distribution of two electron states in a quantum ring in the presence of Rashba spin-orbit interaction (RSOI) and Dresselhaus SOI (DSOI) is investigated in the presence of a perpendicular magnetic field. We find that the interplay between the RSOI and DSOI makes the single quantum ring behaves like a laterally coupled quantum dot and the interdot coupling can be tuned by changing the strengths of the SOIs. The interplay can lead to singlet-triplet state mixing and anticrossing behavior when the singlet and triplet states meet with increasing magnetic field. The two electron ground state displays a bar-bell-like spatial anisotropic distribution in a quantum ring at a specific crystallographic direction, i.e., [110] or [1 (1) over bar0], which can be switched by reversing the direction of the perpendicular electric field. The ground state exhibits a singlet-triplet state transition with increasing magnetic field and strengths of RSOI and DSOI. An anisotropic electron distribution is predicted which can be detected through the measurement of its optical properties.

Fabrication of a Low-Loss SSC Using High-Dose Electron Beam Lithography Exposure With Negative PMMA Resist

A silicon-on-insulator optical fiber-to-waveguide spot-size converter (SSC) using Poly-MethylMethAcrylate (PMMA) is presented for integrated optical circuits. Unlike the conventional use of PMMA as a positive resist, it has been successfully used as a negative resist with high-dose electron exposure for the fabrication of ultrafine silicon wire waveguides. Additionally, this process is able to reduce the side-wall roughness, and substantially depresses the unwanted propagation loss. Exploiting this technology, the authors demonstrated that the SSC can improve coupling efficiency by as much as over 2.5 dB per coupling facet, compared with that of SSC fabricated with PMMA as a positive resist with the same dimension.

Sub-nanosecond silicon-on-insulator optical micro-ring switch with low crosstalk

We demonstrate a sub-nanosecond electro-optical switch with low crosstalk in a silicon-on-insulator (SOI) dual-coupled micro-ring embedded with p-i-n diodes. A crosstalk of -23 dB is obtained in the 20-mu m-radius micro-ring with the well-designing asymmetric dual-coupling structure. By optimizations of the doping profiles and the fabrication processes, the sub-nanosecond switch-on/off time of < 400 ps is finally realized under an electrical pre-emphasized driving signal. This compact and fast-response micro-ring switch, which can be fabricated by complementary metal oxide semiconductor (CMOS) compatible technologies, have enormous potential in optical interconnects of multicore networks-on-chip.

Wafer-Level Testable High-Speed Silicon Microring Modulator Integrated with Grating Couplers

A wafer-level testable silicon-on-insulator-based microring modulator is demonstrated with high modulation speed, to which the grating couplers are integrated as the fiber-to-chip interfaces. Cost-efficient fabrications are realized with the help of optical structure and etching depth designs. Grating couplers and waveguides are patterned and etched together with the same slab thickness. Finally we obtain a 3-dB coupling bandwidth of about 60nm and 10 Gb/s nonreturn-to-zero modulation by wafer-level optical and electrical measurements.

制作用于1.55微米通信波段硅波导光电转换器的方法

本发明公开了一种制作用于1.55微米通信波段的硅波导光电转换器的方法，包括:在SOI的顶层硅上刻蚀出直波导和环形波导，使二者相切或保持一定的耦合关系;在环形波导两侧分别注入或扩散V族和III族离子并退火，形成波导侧壁连续的n型和p型掺杂区，在环形波导表层构造横向p-i-n结构，并控制本征区i的宽度;向环形波导表面的本征区i内注入硅离子、银离子或氢离子，并退火，形成深能级缺陷;在n型和p型掺杂区表面、以及SOI材料背面分别蒸发金属电极，形成非带隙吸收、深能级电荷遂穿、波长可调的硅波导光电转换器。利用本发明，使硅波导p-i-n横向结构对1.55微米波段能够进行探测，并利用热效应来调节转换波长。

硅基级联谐振腔结构的低功耗电光调制器

本发明公开了一种硅基级联谐振腔结构的低功耗电光调制器，该电光调制器由制作在绝缘体上硅SOI衬底上的两个法布里-珀罗谐振腔(4)串联而成，该两个法布里-珀罗谐振腔(4)采用游标式级联的形式串联形成级联谐振腔结构的低功耗电光调制器。所述法布里-珀罗谐振腔(4)由两个布拉格光栅(3)与位于该两个布拉格光栅之间的脊形波导(1)构成，布拉格光栅(3)作为该法布里-珀罗谐振腔(4)的反射镜。本发明大幅提高了谐振腔的F值、FSR、Q值等参数，使得电光调制器的消光比大大增加，调制所需功耗更小，速度更快，而且器件结构紧凑，制作工艺与成熟的微电子CMOS工艺兼容。

倒锥波导耦合器的制作方法

一种倒锥波导耦合器的制作方法，包括如下步骤:步骤1:在SOI上用电子束光刻和感应耦合等离子体刻蚀技术，将SOI的硅波导层刻蚀为一倒锥波导和微纳波导集成器件;步骤2:利用有机/无机杂化的溶胶凝胶法制备光敏性溶胶薄膜材料;步骤3:在SOI的SiO2隔离层及倒锥波导和微纳波导集成器件上旋涂溶胶薄膜;步骤4:对旋涂的溶胶薄膜进行前烘、凝胶;步骤5:在溶胶薄膜上利用掩模版进行紫外写入;步骤6:腐蚀掉紫外写入区以外的部分溶胶薄膜，形成光纤耦合波导，该光纤耦合波导和倒锥波导构成倒锥波导耦合器;步骤7:后烘，完成倒锥波导耦合器的制作。

Flexible Control of Light Propagation Using a Novel Photonic Crystal Hetero-Waveguide Based on Silicon-on-Insulator Slab

We demonstrate a photonic crystal hetero-waveguide based on silicon-on-insulator (SOI) slab, consisting of two serially connected width-reduced photonic crystal waveguides with different radii of the air holes adjacent to the waveguide. We show theoretically that the transmission window of the structure corresponds to the transmission range common to both waveguides and it is in inverse proportion to the discrepancy between the two waveguides. Also the group velocity of guided mode can be changed from low to high or high to low, depending on which port of the structure the signal is input from just in the same device, and the variation is proportional to the discrepancy between the two waveguides. Using this novel structure, we realize flexible control of transmission window and group velocity of guided mode simultaneously.

Study of GaN growth on ultra-thin Si membranes

10 mu m-thick ultra-thin Si (111) membranes for GaN epi-layers growth were successfully fabricated on silicon-on-insulator (SOI) substrate by backside etching the handle Si and buried oxide (BOX) layer. Then 1 mu m-thick GaN layers were deposited on these Si membranes by metal-organic chemical vapor deposition (MOCVD). The crack-free areas of 250 mu m, x 250 mu m were obtained on the GaN layers due to the reduction of thermal stress by using these ultra-thin Si membranes, which was further confirmed by the photoluminescence (PL) spectra and the simulation results from the finite element method calculation by using the software of ANSYS. In this paper, a newly developed approach was demonstrated to utilize micromechanical structures for GaN growth, which would improve the material quality of the epi-layers and facilitate GaN-based micro electro-mechanical system (MEMS) fabrication, especially the pressure sensor, in the future applications. (C) 2008 Elsevier Ltd. All rights reserved.

Recent progresses of Si-based photonics in chinese main land

Si-based photonic materials and devices, including SiGe/Si quantum structures, SOI and InGaAs bonded on Si, PL of Si nanocrystals, SOI photonic crystal filter, Si based RCE (Resonant Cavity Enhanced) photodiodes, SOI TO (thermai-optical) switch matrix were investigated in Institute of Serniconductors, Chinese Academy of Sciences. The main results in recent years are presented in the paper. The mechanism of PL from Si NCs embedded in SiO2 matrix was studied, a greater contribution of the interface state recombination (PL peak in 850 similar to 900 nm) is associated with larger Si NCs and higher interface state density. Ge dots with density of order of 10(11) cm(-2) were obtained by UHV/CVD growth and 193 nm excimer laser annealing. SOI photonic crystal filter with resonant wavelength of 1598 nm and Q factor of 1140 was designed and made. Si based hybrid InGaAs RCE PD with eta of 34.4% and FWHM of 27 nut were achieved by MOCVD growth and bonding technology between InGaAs epitaxial and Si wafers. A 16x16 SOI optical switch matrix were designed and made. A new current driving circuit was used to improve the response speed of a 4x4 SOI rearrangeable nonblocking TO switch matrix, rising and failing time is 970 and 750 ns, respectively.