新型噁二唑有机电致发光小分子光电性质研究

通过升降温差热分析(DSC)曲线、偏光显微镜、紫外吸收光谱、电化学行为曲线以及多层器件等,研究了噁二唑衍生物小分子的电学和光学性质,发现其同时具有液晶性、电子和空穴传输性、发光性等优良性能.引进R-OXD(En)层后的多层器件在低于3 V时就能得到可见光发射,在7 V时可以得到光亮度为1000 cdm^-2.此系列小分子可降低有机电致发光器件开启电压,提高发光亮度和发光效率,是一种非常具有吸引力的有机电致发光小分子.     

Characterization of thermal, optical and carrier transport properties of porous silicon using the photoacoustic technique

In this work, the porous silicon layer was prepared by the electrochemical anodization etching process on n-type and p-type silicon wafers. The formation of the porous layer has been identified by photoluminescence and SEM measurements. The optical absorption, energy gap, carrier transport and thermal properties of n-type and p-type porous silicon layers were investigated by analyzing the experimental data from photoacoustic measurements. The values of thermal diffusivity, energy gap and carrier transport properties have been found to be porosity-dependent. The energy band gap of n-type and p-type porous silicon layers was higher than the energy band gap obtained for silicon substrate (1.11 eV). In the range of porosity (50-76%) of the studies, our results found that the optical band-gap energy of p-type porous silicon (1.80-2.00 eV) was higher than that of the n-type porous silicon layer (1.70-1.86 eV). The thermal diffusivity value of the n-type porous layer was found to be higher than that of the p-type and both were observed to increase linearly with increasing layer porosity.     

Enhancement of the evanescent field using polymer waveguides fabricated by deep UV exposure on mesoporous silicon

Polymer integrated reverse symmetry waveguides on porous silicon substrate fabricated by using deep ultraviolet radiation in poly(methyl methacrylate) are presented. The layer sequence and geometry of the waveguide enable an evanescent field extending more than 3 microm into the upper waveguide or analyte layer, enabling various integrated optical devices where large evanescent fields are required. The presented fabrication technique enables the generation of defined regions where the evanescent field is larger than in the rest of the waveguide. This technology can improve the performance of evanescent-wave-based waveguide devices.     

Nanostructured Au/Si substrate for organic molecule SERS detection

Nanoparticles of noble metals, such as gold and silver, exhibit unique and tunable optical properties on account of their surface plasmon resonance. In particular, gold nanoparticles on silicon substrates are attractive for future nanoscale sensors and optical devices due to their resistance to oxidation and due to their electrical and optical properties. In this study, we developed a nanostructured gold/macroporous silicon (Au/PS) substrate capped with 11-mercaptoundecanoic acid (11-MUA) with ultra-sensitive detection properties achieved in characterization, an approach based on surface-enhanced Raman scattering (SERS). Surface-enhanced Raman scattering allows us to detect substances at a low concentration level and to observe structural details of a thiol molecule bonded to small film thicknesses. Raman measurements were carried out at 514 nm and 785 nm. In order to emphasize the effect of the Si microstructuration on the efficiency of this new substrate (Au/PS) proposed for SERS experiments, the same molecule (11-MUA) was adsorbed on it as well as on gold/atomically flat silicon (Au/Si) and on commercial Klarite (Mesophotonics) substrates. Systematic studies realized by Raman spectroscopy, electron microscopy, and X-ray spectroscopy show the influence of silicon substrate texturing and metallic deposition conditions, including time and temperature on the optical phenomena.     

Low loss optical channel waveguides for the infrared range using niobium based hybrid sol-gel material

In this work, we report the fabrication of single-mode Nb₂O₅ based hybrid sol-gel channel waveguides. Nb₂O₅ based hybrid sol-gel material has been deposited by spin-coating on silicon substrate and channel waveguides have been fabricated by a UV direct laser writing process. Optical guided modes have been observed to confirm single-mode conditions and optical propagation loss measurements have been performed using the cut-back technique. Optical propagation losses were measured to be 0.8 dB/cm and 2.4 dB/cm at 1.31 μm and 1.55 μm respectively. These experimental results demonstrate low loss optical waveguiding within the infrared range and are very promising in view of material choice for the development of integrated optical devices for telecommunication.     

GaN基发光二极管衬底材料的研究进展

GaN基发光二极管(LED)作为第三代照明器件在近年来发展迅猛.衬底材料作为LED制造的基础,对器件制备与应用具有极其重要的影响.本文分析综述了衬底材料影响LED器件设计与制造的关键特性(晶格结构、热胀系数、热导率、光学透过率、导电性),对比了几种常见衬底材料(蓝宝石、碳化硅、单晶硅、氮化镓、氧化镓)在高质量外延层生长、高性能器件设计和衬底材料制备方面的研究进展,并对几种材料的发展前景做出了展望.     

Integrated optical proximity microsensor

This paper presents the design, simulation and experimental results of an integrated proximity sensor manufactured on silicon substrate. The sensor was designed for microrobotic applications like integration into a microgripper arm or detection of the position of gripper arms relative to an object. The structure is based on an SU8 polymeric optical waveguide splitted into three arms, integrated with a multielement photodetector on silicon substrate. Each element of the photodetector is a metal-semiconductor-metal (MSM) photodiode with Ti/Al Schottky interdigitated electrodes.The operation principle of this sensor consists in the light coupling in the central arm of the optical waveguide, interaction with the object (reflection) of the radiation which exits from this principal arm, the coupling of the “affected” radiation which comes back through the end of the waveguide and its splitting into three arms of the optical waveguide. From the optical waveguide, the light is coupled in photodiode and the photogenerated carriers are collected to the electrodes giving the electrical signal which is read and processed in real time.The optimal parameters of the waveguide (width, thicknesses of the core and the claddings) of the photodetector and the coupling between them were defined by simulation, using FDTD and BeamProp method (Opti FDTD software). Our microsensor can detect the position of an object in the range of 0-300 μm, as position sensor and with high precision in the range of zero to twice the wavelength, as proximity sensor.     

Quantum dot lasers and integrated optoelectronics on silicon platform Invited Paper

Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot (QD) lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of selforganized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength (> 1.3 μm) QD lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.     

Heterogeneous integration of InGaAsP microdisk laser on a silicon platform using optofluidic assembly

Heterogeneous integration of InGaAsP microdisk lasers on a silicon platform is demonstrated experimentally using an optofluidic assembly technique. The 200-nm-thick, 5- and 10-μm-diameter microdisk lasers are fabricated on InP and then released from the substrates. They are reassembled on a silicon platform using lateral-field optoelectronic tweezers (LOET). The assembled laser with 5-μm diameter exhibits a threshold pump power of 340 μW at room temperature under pulse condition. The heterogeneously-integrated InGaAsP-on-Si microdisk laser could provide the much needed optical source for CMOS-based silicon photonics. The small footprint and low power consumption make them attractive for optical interconnect applications. The optofluidic assembly technique enables efficient use of the III–V epitaxial materials in silicon photonic integrated circuits.     

Optical signal processing using four wave mixing in highly nonlinear silicon nano-wire

Silicon-on-insulator (SOI) waveguide devices are emerging for the realization of optical signal processing systems for the last couple of years. The recent technological advancement in silicon photonics is the main driving force at the back of these devices. Using non-linear optical phenomenon in silicon wires and their compatibility with CMOS devices provide the stage for integrated photonic devices. All-optical signal processing devices are being investigated at present, but the chip-scale solution provided by the silicon photonics is the most promising. In this research we have investigated all-optical signal processing in a 10 mm long SOI waveguide by exploiting well established coupled wave equations. We consider single pulsed pump to analyze frequency shifting by four-wave-mixing (FWM). For the wavelengths 20?30 nm far from the pump, the gain overcomes nonlinear losses resulting in higher frequency conversion efficiency.     

Growth and properties of InGaAs nanowires on silicon

Free‐standing ternary InGaAs nanowires (NW) are at the core of intense investigations due to their integration capabilities on silicon (Si) for next‐generation photovoltaics, integrated photonics, tunneling devices, and high‐performance gate all‐round III–V/Si NW transistors. In this review, recent progress on the growth, structural, optical and electrical properties of InGaAs NWs on Si substrate is highlighted. Particular focus is on a comparison between conventional catalyst‐assisted and catalyst‐free growth methods as well as self‐assembled versus site‐selectively grown NW arrays. It will be shown that catalyst‐free, high‐periodicity NW arrays with extremely high compositional uniformity are mandatory to allow un‐ambiguous structure–property correlation measurements. Here, interesting insights into the electronic/optical properties of wurtzite, zincblende and mixed crystal phases of InGaAs will be highlighted based on recent photoluminescence spectroscopy data. Finally, the InGaAs NW‐on‐Si system is also discussed in the realms of heterojunction properties, providing a promising system for steep‐slope tunneling field effect transistors in future low‐power post‐CMOS intergrated microelectronics and broad‐band photoabsorption and detec‐tion devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Functional integration of microdevices by field assisted manipulation and trapping

A novel programmable force field method is presented which enables controlled electric field assisted transport and localization of microdevices at silicon chip substrates. Electrically addressable chips bearing n×n arrays of receptor electrode sites are developed and field directed assembly methods are optimized for on-chip transport, trapping and integration of sub-100 m discrete GaAs-based optoelectronic devices. Tweezer-less field assisted manipulation and trapping of discrete 50 m diameter 670 nm emitting GaAs-based light emitting diodes is achieved. Following assembly in this manner, the LED devices are permanently integrated by solder reflow bonding to the receptor sites enabling direct device electrical characterization and successful demonstration of light emission. PACS 81.16Dn; 81.05.Hd; 42.82.Fv; 42.82.Gw     

电泳沉积法制备V2O5薄膜的结构和性能

将V2O5溶胶电泳沉积在ITO导电基片上制备V2O5薄膜.运用X射线衍射和扫描电镜对薄膜的结构进行分析,通过紫外-可见光透射光谱和循环伏安法分别测试其光学和电化学性能.实验结果表明,电泳沉积V2O5薄膜具有致密的显微结构,薄膜厚度均匀、与基片的粘附性很好;循环实验中,薄膜呈现黄色到绿色的可逆变化,最大的透射率变化达到30%左右;薄膜具有很好的注入/退出可逆性和循环稳定性,50次循环效率仍能达到88.02%,并且循环后的薄膜与ITO导电玻璃的粘附性仍然很好,没有溶解现象;应用交流阻抗法计算Li+在V2O5薄膜着色过程的扩散系数为5.10×10-12cm2/s,表明该薄膜可以作为电致变色材料得到应用.     

Arrays of silicon microdischarge devices with multicomponent dielectrics

Arrays as large as 15x15 of microdischarge devices having inverted pyramidal silicon cathodes (50mumx50mum) and SiO(2)- Si(3)N(4)- polymer composite dielectrics have been fabricated and characterized with Ne gas. The lifetimes, reliability, and ignition characteristics of the arrays are superior to those of earlier designs having a single polymer dielectric. Operating voltages as low as 150 V for a 10x10 pixel array and 1000 Torr of Ne have been measured. Single (50mumx50mum) pyramidal cathode devices operate at voltages as low as 113 V when the Ne pressure is 900 Torr.     

Electrical behaviors of ZnO/graphene/Si and ZnO/graphene/PS composite structures obtained by spraying different volumes of graphene solution

In this paper, a novel ZnO/graphene/porous silicon hybrid device is fabricated and its electrical behaviors are studied along with a ZnO/graphene/silicon device. Graphene (G) is prepared by exfoliation of graphite foil in aqueous solution of inorganic salt. Porous silicon (PS) is fabricated by electrochemical etching of p-type silicon (Si). Graphene is deposited on the surface of Si and PS substrates by thermal spray pyrolysis method. ZnO rods are grown on the samples by using catalyst-free chemical vapor transport and condensation method. The current–voltage relationships of ZnO/G/Si and ZnO/G/PS devices are studied under different volumes of graphene solution. The results reveal the distinctive features of the I–V characteristics of the two devices for different volumes of graphene solution under room light as well as UV illumination.     

The effects of porous silicon on the crystalline properties of ZnO thin films

In the present work, ZnO was deposited on porous silicon substrates by sol-gel spin coating and rf magnetron sputtering. The porous silicon (PS) substrates were formed by electrochemical anodization on p-type (1 0 0) silicon wafer, and the starting material for ZnO was Zinc acetate dehydrate. Raman spectroscopy revealed the good quality of the porous silicon substrate. XRD analysis showed that highly (0 0 2) oriented ZnO thin films were formed. SEM, AFM and optical microscope have been used to understand the effects of the substrate on crystalline properties of the samples. The results indicated that the porous silicon substrate is beneficial to improve the crystalline quality in lattice mismatch heteroepitaxy due to its sponge-like structure.     

纤维光锥有效透过率的理论分析

光锥的有效透过率不仅影响光锥与CCD的耦合效率,而且会影响到耦合器件的信噪比.本文主要从理论上讨论了影响光锥有效透过率性能的因素,从纤维光学元件的实际内部结构推导出了其实际有效填充率,从光线在光锥中的传输特征推导出了光线在光锥中传播时产生的衰减损耗,最后提出了提高光锥有效透过率的方法和途径.     

硅基混合表面等离子体纳米光波导及集成器件

总结并展望了硅基混合表面等离子体纳米光波导及集成器件方面的理论和实验研究工作。首先介绍了几种硅基混合表面等离子体纳米光波导结构,其尺寸可小至100 nm以下,而传播长度达100μm量级;其次介绍了基于硅基混合表面等离子体纳米光波导的功分器、偏振分束器和谐振器等集成器件,其尺寸为亚微米量级;最后探讨了硅基混合表面等离子体纳米光波导与硅纳米线光波导的耦合及对其进行增益补偿。     

Single-photon imaging at 20,000 frames/s

A complete two-dimensional imaging system based on a silicon monolithic array of 60 single-photon counters is presented. The fabricated solid-state array is rugged and operates at low voltages. Detection efficiency is higher than 40% in the visible range, and cross talk among 50 microm pixels is lower than 10(-4). The complete system provides a maximum throughput of 20 kframes/s with truly parallel readout and nanosecond gating, thanks to the use of an integrated active quenching circuit for each pixel of the array. We report optical and electrical characterizations of the whole imaging system.     

Nanomembrane transfer process for intricate photonic device applications

We demonstrate a process for the fabrication and transfer of silicon nanomembranes (Si-NMs) that have been released from their host substrates and redeposited on foreign flexible or flat substrates. The transfer process developed allows intricate photonic devices to be transferred via NMs to a variety of new substrate materials. This allows the transferred devices to benefit from the material properties of both substrate and NM. Our process is designed to transfer and stack large-area photonic devices without compromising their optical performance. The process has been used to transfer large-area unpatterned silicon NMs, in excess of 2.5 cm(2), and photonic devices with intricate device designs containing various fill factors. We have also demonstrated transferred photonic crystal devices that have maintained structural integrity and functionality.