光电导型混晶Si1-xGex波导探测器

首次报导了光电导型混晶Ｓｉ－ｘＧｅｘ波导探测器。混晶Ｓｉ１－ｘＧｅｘ是在硅基ＳｉＯＮ／ＳｉＯ２／Ｓｉ上用快速加热超低压化学气相淀积生长并经６５０℃退火３０ｍｉｎ得到的。探测器宽１０μｍ,长２ｍｍ。探测器加２０Ｖ偏置电压是,探测灵敏在０．０２２－０．０１０Ａ／Ｗ之间。混晶Ｓｉ１－ｘＧｅｘ造成探测器的光谱响应曲线发生蓝移。当锗组分ｘ＝０．３５、０．４、０．５、和０．６时,探测器峰值波长分别对应为８７５     

提高Si3N4抗氧化性能的陶瓷涂层

采用Ｓｏｌ－Ｇｅｌ法在热压Ｓｉ３Ｎ４表面涂上一层ＳｉＯ２涂层，用Ｘ光电子能谱（ＸＰＳ）检测了涂覆ＳｉＯ２后Ｓｉ３Ｎ４表面的组成，结果表明，在Ｓｉ３Ｎ４表面有ＳｉＯ２涂层存在，经涂覆 热压Ｓｉ３Ｎ４在１３０℃氧化１００ｈ后，氧化增重从未涂覆的０．４２ｍｇ／ｃｍ＾２降到０．２８ｍｇ／ｃｍ＾２。     

生物材料PCL的晶体结构

用ＷＡＸＤ方法测定了生物高分子材料ＰＣＬ的晶体结构。求出晶胞参数数ａ＝０．７４７２ｎｍ，ｂ＝０．４９９５ｎｍ，ｃ＝＝１．７０５０ｎｍ，Ｖ＝０．６３６３ｎｍ＾３及晶体密度Ｄｃ＝１．２０ｇ／ｃｍ＾３；ｚ＝４属正交晶系；对称性分离，属Ｐ２２２空间群，Ｎ＝２，分子链构橡为ＰＺ型，并给出了晶结构模型。     

复合型Si光电发射材料

采用碱锑化合物的镀制与铯氧激活可制备复合型Ｓｉ光电发射材料（Ｓｉ－Ｎａ＿２Ｓｂ－Ｃｓ）－Ｏ－Ｃｓ，（Ｓｉ－Ｋ＿３Ｓｂ－Ｃｓ）－Ｏ－Ｃｓ，（Ｓｉ－Ｃｓ＿３Ｓｂ－·Ｃｓ）－Ｏ－Ｃｓ和（Ｓｉ－Ｎａ＿２ＫＳｂ－Ｃｓ）－Ｏ－Ｃｓ，其最高灵敏度分别可达９５０，１０５０，１５０和２０００μＡ／１ｍ，其最低逸出功分别已达１．０，０．９，０．８５和０．９ｅＶ。比较了复合型Ｓｉ光电发射材料与Ｓｉ和Ｎａ＿２ＫＳｂ（Ｃｓ）光电材料的一些性能参数，提出了复合型Ｓｉ光电材料的表面原子模型；讨论了复合型Ｓ光电材料的光电发射过程并分析了碱锑过渡层的作用。     

Fe73.5Cu1Mo3Si13.5B9微晶软磁合金的结构及其对磁性的影响

对Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９微晶软磁合金的结构及其对合金磁性的影响了研究，结果表明，在最佳磁性能下，晶相点阵常数ａ＝０．２８４３ｎｍ，相当于Ｆｅ（Ｓｉ）固溶体中含Ｓｉ％（ｍｏｌ／ｍｏｌ）：１８－２０，体积百分数Ｖ＝７４．８％，晶粒尺寸Ｄ＝１４．６ｎｍ；残余非晶层厚度δ＝１．２３ｎｍ；当Ｔ退火≥５６０℃时明显有Ｆｅ－Ｂ化合物析出。Ｆｅ７３．５Ｃｕ１Ｍｏ３Ｓｉ１３．５Ｂ９合金的磁性不仅与     

溶胶—凝胶碳热法制备超细Si3N4粉的研究

本文报道了用溶胶－凝胶碳热氮化法、在高氮气压下（１．５ＭＰａ）各种参数对氮化硅生成的影响。在１７００℃／５ｈ下能得到初始粒径为几十ｎｍ的超细α－Ｓｉ３Ｎ４粉，氮含量达３８ｗｔ％以上，且无结晶的ＳｉＯ２和ＳｉＣ。     

Si3N4—TiC复合材料的微观结构和化学反应

在１８００℃温度和Ａｒ，Ｎ２气氛下热压试样中，研究了ＴｉＣ加入Ｓｉ３Ｎ４中对ＴｉＣ－Ｓｉ３Ｎ４体系的微观结构和中间相化学反应的影响。根据热力学方法，估算出ＴｉＣ１－ｘＮｘ固溶体的组成，并以氰化钛作为一种理想的固溶体。这个估算值（ｘ＝０．７）略高于通过测定晶格参数和根据Ｖｅｇａｒｄ定律而计算出的值（ｘ＝０．６７）。样品在Ｎ２气中热压后可观察到４个区别明显的相区，它们是β－Ｓｉ３Ｎ４、ＴｉＣ和氰化钛固     

热处理过程中纳米非晶Si－N－C粉的晶化及微结构变化研究

本文在１４７３～１９７２Ｋ温度范围内对激光合成的、平均粒径为３０ｎｍ的非晶Ｓｉ－Ｎ－Ｃ粉进行热处理（ｌａｔｍ．Ｎ２，１ｈ）；研究了粉体的晶化及微结构变化，结果表明，纳米非晶Ｓｉ－Ｎ－Ｃ粉具有短程有序的亚稳结构，此亚稳结构在＞１５２３Ｋ发生稳定团相分离，在１７７３Ｋ开始形成α－Ｓｉ３Ｎ４；β－ＳｉＣ，此时粒子间出现明显的表面扩散形成粒子簇；到１８７３Ｋ晶化加剧，α－Ｓｉ３Ｎ４和β－ＳｉＣ明显增多，并有少量的石墨碳形成。在１７７３～１８７３Ｋ，由固相分离形成α－Ｓｉ３Ｎ４／β－ＳｉＣ纳米复合结构。     

离子束增强沉积Si3N4／Si多层红外干涉滤波薄膜

利用离子束增强沉积工艺，在硅基片上制备Ｓｉ３Ｎ４／Ｓｉ多层红外干涉滤波薄膜。结构表明，Ｎ＾＋２＋Ｎ＋的辅助轰击对于合成接近化学配比的Ｓｉ３Ｎ４薄膜起了关键作用。薄膜的折射率可达１．７４－１．８４。实验测得的多层滤波薄膜的红外反射谱与值相当接近。     

Al—5Fe—2Ni合金析出相的Mossbauer谱

用Ｍｏｓｓｂａｕｅｒ谱学和ＸＲＤ方法研究了快速凝固Ａｌ－５Ｆｅ－２Ｎｉ（原子百分数）合金的析出相，结果表明，析出相为三元化合物Ａｌ９ＦｅｘＮｉ２－ｘ（０〈ｘ〈２）属于单斜晶系，晶格参数ａ＝０．８５８ｎｍ，ｂ＝０．６３１ｎｍ，ｃ＝０．６２１ｎｍ，β＝９４．８，它的Ｍｏｓｓｂａｕｅｒ谱为一套双线，同质异能移位ＩＳ＝０．１２ｍｍ．ｓ＾－１，四极分别ＱＳ＝０．３２ｍｍ．ｓ＾－１，线宽Г＝０．２６ｍｍ．ｓ＾     

Ordered Ge-dot arrays in a Si-waveguide for 1.5 µm detectors

In the present work we demonstrate a Si rib waveguide photodiode based on a vertical p-i-n junction with Ge islands operating in the near infrared spectral region around λ = 1.55 µm at room temperature. The device employs Ge islands as infrared absorbing medium, in which the electron-hole recombination is indirect in k- and real space resulting in long radiative life times. The 5 µm × 230 nm waveguide-like design of the photodiode ensures, on the one hand, a sufficient light path in order to get complete incident light absorption and, on the other hand, efficient and fast separation of the electron-hole pairs by using thin p-i-n junction perpendicular to the direction of light propagation. The Ge islands are precisely positioned in a 2-dimensional grid of periodicity at 460 nm matching the maxima of a standing wave, which can form in the waveguide, thus further enhancing the efficiency of the device.     

Swift and heavy ion implanted chalcogenide laser glass waveguides and their different refractive index distributions

Planar waveguides have been fabricated in Nd- or Ho-doped gallium lanthanum sulfide laser glasses by 60?MeV Ar or 20?MeV N ion implantation. The refractive index profiles were reconstructed based on the results of prism coupling. The Ar implanted waveguides exhibit an approximate steplike distribution, while the N implanted ones show a "well + barrier" type. This difference can be attributed to the much lower dose of Ar ions. After annealing, the N implanted waveguides can support two modes at 1539?nm and have low propagation loss, which makes them candidates for novel waveguide lasers.     

Ultrafast low-threshold all-optical switch implemented by arrays of ring resonators coupled to a Mach-Zehnder interferometer arm: based on 2D photonic crystals

Using an array of m x n nonlinear ring resonators (m = 1, 3, 5, and n = 1, 2, 3) coupled to the upper arm of a Mach-Zehnder interferometer (MZI), we have proposed an all-optical switch structure. Using a 5 x 3 array, we have shown the possibility of designing an all-optical switching device with a threshold intensity as low as 15 mW/m(2) and switching window of approximately 35 ps. While using m x 1 arrays, we have achieved switching windows smaller than 10 ps, at the expense of higher switching thresholds, ranging from 37 to 55 mW/m(2). The whole structure is based on a square lattice photonic crystal of lattice constant a = 600 nm, formed by rods of radius r = 90 nm in an air background. The linear rods' refractive index is taken to be the same as that of Si(0.75)Ge(0.25); i.e., n(r) = 3.6, whereas the nonlinear rod's refractive index and Kerr index parameter are taken to be n(0) = 1.4 and n(2) = 10(-14) m(2)/W. The center wavelength at which the nonlinear rings are designed to make the resonance is taken to be lambda(0) = 1550 nm in free space.     

Photosensitivity in GeO2–SiO2 glasses and optical waveguides

Permanent refractive index changes caused by a KrF excimer laser operating at 248 nm in GeO₂–SiO₂ glasses deposited on Si (100) substrates using flame hydrolysis deposition (FHD) are presented. The sample was amorphouslike investigated by X-ray diffraction (XRD), and the ratio of Ge:Si is 14:86 from X-ray photoelectron spectroscopy (XPS) analysis. The 10-min irradiation with a KrF excimer laser (10 Hz, 187 mJ/cm²) induced a positive refractive index change of 0.341% at 1550 nm, which has achieved an international level of this field. An innovative photomask with a Cr-loaded structure coated on a UV quartz glass, was used to fabricate a 50 μm gap with a period of 100 μm waveguide grating under 1460 mJ/cm²/pulse at 6 Hz, and the diffraction patterns were observed clearly. The extinction coefficients of the samples are also measured over the range 250–1600 nm.     

Slow-light Mach–Zehnder modulators based on Si photonic crystals

Mach–Zehnder optical modulators are the key devices for high-speed electrical-to-optical conversion in Si photonics. Si rib waveguides with a p–n diode structure operated in the carrier depletion mode have mainly been developed as their phase shifters. Their length is usually longer than millimeters due to the limited change in the refractive index due to the carrier depletion in a Si p–n diode. This length is shorter than commercial LiNbO₃ modulators, but still much shorter devices are desired for large-scale integration and for simplifying the high-speed RF modulation. A promising solution is to use slow light in photonic crystal waveguides, which enhances the modulation efficiency in proportion to the group-velocity refractive index n_g. In particular, dispersion-engineered slow light allows more than five-fold enhancement, maintaining a wide working spectrum as well as large temperature tolerance. The devices with a phase shifter length of around 100 μm are fabricated by a standard process compatible with complementary metal-oxide semiconductors. The operation at 10 Gbps and higher speeds are obtained in the wavelength range of 16.9 nm and temperature range of 105 K.     

High quality ZnO layers with adjustable refractive indices for integrated optics applications

Thin ( 1 μm) crystalline ZnO films with a good optical quality and good (0002) texture are grown under two considerably different process parameter sets using a r.f. planar magnetron sputtering unit. The optical parameters of the two corresponding ZnO layers are distinctly different: high refractive index ( 2.0 at λ = 632.8 nm) ZnO films resembling the single crystal form, and ZnO films with considerably lower (typical difference 0.05) refractive indices. The refractive index of the latter ZnO layers is adjustable ( 1.93–1.96 at λ = 632.8 nm) through the process deposition parameters. It is shown that the difference in refractive index between the two ZnO types most probably results from a difference in package density of the crystal columns. The optical waveguide losses of both ZnO types are typically 1–3 dB/cm at λ = 632.8 nm, however the low refractive index ZnO layers need a post-deposition anneal step to obtain these values. The two ZnO types are used to fabricate optical channel-and slab waveguides with small refractive index differences.     

Si_3N_4/Si表面Ge生长过程的STM研究

利用STM和LEED分析了Ge在Si3 N4 /Si(111)和Si3 N4 /Si(10 0 )表面生长过程的结构演变。在生长早期 ,Ge在两种衬底表面上都形成高密度的三维纳米团簇 ,这些团簇的大小均在几个纳米范围内 ,并在高温退火时体积增大。当生长继续时 ,Ge的晶体小面开始显现。在晶态的Si3 N4 (0 0 0 1) /Si(111)表面 ,Ge的 (111)晶向的小面生长比其他方向优先。最后在大范围内形成以 (111)方向为主的晶面。相反 ,在非晶的Si3 N4 表面 ,即Si3 N4 /Si(10 0 ) ,Ge晶体的高指数侧面生长较顶面快 ,最终形成金字塔形的岛结构。对这样的表面生长过程进行了探讨并给出了合理的物理解释     

Deposition Temperature Effect on the Structure and Optical Property of RF‐PACVD‐Derived Hydrogenated SiCNO Film

Amorphous hydrogenated silicon oxocarbonitride (SiCNO:H) films have been deposited by plasma‐assisted chemical vapour deposition (PACVD) using bis(trimethylsilyl)carbodiimide (BTSC) as a single source precursor in a argon (Ar) radio‐frequency plasma. In this work the SiCNO:H films deposited at different deposition temperatures were studied in terms of deposition rate, refractive index, surface roughness, microstructure, and chemical composition including bonding state. The results showed that a higher deposition temperature enhanced the formation of Si‐N bonds, and disfavoured the formation of N=C=N, Si‐NCN, C‐H and Si‐CH₃ bonds. A higher deposition temperature also decreased the deposition rate and increased the refractive index of the resulting SiCNO:H film. With increasing temperature a denser film was formed, indicating a change of the deposition mechanism, i.e., transformation from particle precipitation to heterogeneous surface reaction. Except for the coatings deposited at room temperature, the surface of the films was smooth with a roughness of around 4 nm at the centre in the range of 5 μm x 5 μm area. Moreover, the films contained 8 ～ 16 at.% oxygen bonded to Si, which originated from the remnant H₂O in the deposition chamber.     

Slot optical waveguide usage in forming passive optical devices

We have reviewed the work on SOI slot optical waveguides followed by our work. In a slot waveguide structure, light can be confined in a low index slot guarded by high index slabs. Slot structures are being used in forming complex structures; such as ring resonator circuits. The increased round trip in ring resonator circuits signifies the importance of dispersion calculations. We did analytical and numerical investigations of slot structures' dispersion characteristics. Our dispersion tuned slot structures can help in reducing the dispersion effects on optical signal, which will in turn improve the efficiency of light-on-chip circuits. Since the advent of slot optical waveguides, SOI based slot optical waveguides have been under consideration. It has been found that glass based slot optical waveguide structures with relatively low refractive index contrast ratio can also play an important role in forming complex nano-size optical devices. We made use of power confined inside low index slot regions for a double slot structure. Opto-mechanical sensors have been proposed based upon: (a) variation in power confined inside low index slot region due to the movement of central high index slab under the action of external force (temperature, pressure, humidity, etc). vide Chinese Patent No. ZL 200710176770.1, 2007 (b) variation in power confined inside low refractive index slot regions due to movement of both slots under the action of external force (temperature, pressure, humidity, etc).     

Silver-doped germanium sulphide glass channel waveguides fabricated by chemical vapour deposition and photo-dissolution process

Germanium sulphide glass thin films have been fabricated by chemical vapour deposition directly on commercial glass substrates. Silver (Ag)-doped channel waveguide structures were then prepared in a three step process, first channels were patterned in photo-resist, next a Ag thin film was deposited on the patterned waveguide by thermal evaporation, and finally the silver ions were doped into germanium sulphide glass by a photo-dissolution process. The refractive index of germanium sulphide increased by about 0.02 through the photo-dissolution process. The loss of the channel waveguides measured at 632.8 nm was 0.63 ± 0.05 dB/cm.