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We proposed an ultra-thin Si-padded

We propose and demonstrate a novel Si/Si 3 N 4 composite waveguide structure potentially for implementing low-loss and high-speed photonic integrated circuits. The measured waveguide propagation loss is 0.46 dB/cm.

We present an asymmetric dual-level grating coupler fabricated on an ultra-thin Si/Si 3 N 4 composite photonics platform to achieve a high coupling efficiency for light coupled from a single-mode fiber to the waveguide and vice versa.

A miniaturized mmWave-over-fiber remote radio head implemented by heterogeneous integration of Si photonics and CMOS integrated circuits is presented. A 28-GHz, 16-QAM OFDM signal is transmitted through this module with EVM 9.52%.

Here, an efficient intracellular delivery of molecules with high cell viability is reported using nanosecond-pulsed laser-activated plasmonic photoporation, mediated by high-aspect-ratio nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles (nm-AuPNPs) at near-infrared wavelength. Upon pulsed laser illumination, nm-AuPNPs exhibit greater plasmonic extinction than spherical AuPNPs, which increase their energy efficiency and reduce the necessary illumination of light, effectively controlling cell damage and improving the delivery efficiency. Nm-AuPNPs exhibit surface plasmon absorption at near infrared region with a peak at 945 nm. Pulsed laser illumination at this plasmon peak triggers explosive nanobubbles, which create transient membrane pores, allowing the delivery of dyes, quantum dots and plasmids into the different cell types. The results can be tuned by laser fluence, exposure time, molecular size and concentration of nm-AuPNPs. The best results are found for CL1-0 cells, which yielded a 94% intracellular PI dye uptake and ∼100% cell viability at 35 mJ cm−2 laser fluence for 945 nm wavelength. Thus, the presented approach has proven to have an inevitable potential for biological cell research and therapeutic applications.

Optomechanics of colloidal microparticles has wide applications in biological analysis and sensing. For colloidal microspheres or microdroplets, the optomechanical force can be magnified through the cavity enhancement effect. However, it is difficult to analyze the force since the colloidal microspheres are suspended in liquid, and addressing a movable microsphere at a specific position in three-dimensional space is also challenging. An on-chip integrated operating platform comprising waveguides and microelectromechanical systems is employed to study the cavity-enhanced optical gradient force on colloidal microspheres, owing to the ability to precisely control the distance between a suspended microsphere and a waveguide through dielectrophoretic force. We introduce two kinds of optomechanical coupling mechanisms at resonance, depending on the initial coupling gap without inclusion of the optical gradient force. One is self-adjusted coupling, where the coupling gap of a suspended microsphere continuously varies with the optical input power, and the other is bistable coupling, where the coupling gap hops from one state to the other as the input power exceeds over a threshold value, which is caused by the nature of nonlinear gap-dependent optical gradient force.

In this paper, we present an ultra-sensitive photonic refractive index (RI) sensor based on nanoporous silicon (NPS) one-dimensional (1D) microcavity structures for detecting heavy metal ions in water. Consisting of two distributed Bragg reflectors (DBR) symmetrically placed about a defect layer fabricated by successive electrochemical etchings (ECE), the 1D microcavity is employed to enhance the sensitivity of the sensors. Although these RI sensors possess the property of high sensitivity to RI change and high resolution due to high porosity and narrow resonance peak, respectively, however their selectivities to analytes are poor, and limit of detections (LOD) are also restricted owning to passive interaction between analytes and sensors. To solve these problems, we propose a new procedure for heavy metal ion detection that offers good selectivity and ultra-low LOD while keeping the advantages in sensitivity and resolution of the NPS sensor. In the procedure, an electrochemical reduction process is applied to actively/selectively pre-concentrate and reduce metal ions on the pore surfaces of the NPS that results in the improvement in selectivity and LOD. This ECA-NPS based photonic sensor was applied to detect cadmium ions in deionized water revealing a sensitivity of 342 nm/RIU and 0.152 ppb of LOD in DI water. LOD as low as 1.16 ppb with a selectivity over sodium, potassium, magnesium, calcium and nickel etc, has also been demonstrated with a longer reduction time of 20 min for 10 ppb cadmium ions spiked in lake water.

In this study, an integrated operation platform is proposed to study colloidal microsphere and microdroplet resonators on a chip. Via varying dielectrophoretic force induced on a specially designed concentric ring electrode, spherical optical resonators are able to be precisely controlled on their position relative to an integrated waveguide with resolution down to tens of nanometer, which is crucial to determine the coupling condition of the resonator. A solid-state polystyrene microsphere and an immersion oil droplet are demonstrated with ability to be freely operated in undercoupling, critical coupling, and overcoupling regimes. Through this platform, a metrology technique is reported to precisely measure the radius of a microdroplet by examining the resonant modes. This platform could be a useful tool to study optical resonance of spherical objects dispersed in water.

We presented a surface plasmon resonance (SPR) sensor with an angular sensitivity up to 440 deg/RIU by using (±1,∓1) mode on a hexagonal gold nanohole array. The large-area gold nanohole arrays were fabricated by thermal-annealing template-stripping method with 180-nm-hole diameter and 600-nm period. A flat dispersion curve deviated from Bragg condition for (±1,∓1) mode occurred when incident angle was larger than 20°. The finite-difference time-domain calculations verified that plasmonic mode changed from surface plasmon mode to cavity mode in nanoholes. Such mode transition resulted in the large change of dispersion curve. The angular sensitivity of the (±1,∓1) mode near the transition band was 6.2 times higher than surface plasmon mode under Bragg condition and 4.5 times higher than prism-based SPR sensors at 850 nm wavelength. Biosensing experiments for antigen-antibody interactions verified the surface binding sensitivity was higher than prism-based SPR machine.

Metal-semiconductor-metal (MSM) photodetectors made of gallium antimonide (GaSb) on silicon waveguides by the rapid melt growth method are investigated. By controlling the thermodynamics of crystal regrowth and optimizing the process condition, single-crystal GaSb stripes are monolithically integrated on the silicon substrate. The MSM GaSb waveguide photodetector shows a responsivity of 0.57 A/W at 1550 nm.

We studied using rapid melt growth (RMG) method to make GaSb microdisks on Si substrate. By optimizing the process condition, we observe a strong photoluminescence.

The efficient monolithic III-V integration on silicon (Si) substrates can leverage the excellent optoelectronic properties of III-V semiconductors and the Si microfabrication technology for electronic, optoelectronics, integrated photonics devices. However, the origin of the interfacial and material defects during III-V monolithic integration on Si poses the challenge to achieve efficient optical emitters, detectors. In this study, we investigated different surface treatment schemes before rapid melt growth (RMG) of GaSb on Si substrate to attain defect control. The deposition of an Sb layer (10 nm) on GaSb precursors surfaces resulted in achieving better structural and optical properties of GaSb post RMG. We achieved a reduction of 2.48 atomic % of unintentional incorporation of Si into the GaSb via Sb treatment compared to that of untreated GaSb analysed using transmission electron microscopy and energy-dispersive X-ray spectroscopy. Improved surface morphology with reduced root mean square roughness of 3.7 nm is obtained with Sb layer treatment compared to 5.6 nm for untreated GaSb precursor measured by atomic force microscopy. We obtained improved optical properties and low defect density with an in-situ Sb treatment scheme on GaSb precursor surface by µ-Photoluminescence and µ-Raman spectroscopy analysis.

Fabrication of three-dimensional (3D) SU-8 (an epoxy-based negative photoresist from MicroChem) prisms as low-loss couplers for interconnection between optical components, particularly optical fibers and silicon-on-isolator waveguides (SOI WGs), which have mismatched mode sizes, has been investigated. With an interfacial structure formed by a 3D SU-8 prism partly overlaying an SOI WG end with a portion of buried oxide (BOX) removed under the interface, low-loss coupling is ensured and the transmission efficiency can reach 70%. To fabricate these 3D SU-8 prisms, a simple method with two photolithography steps was used for SU-8 hinges and CYTOP (an amorphous fluoropolymer from AGC Chemicals) prism windows, with mild soft and hard bakes, to define the prism profiles with diluted SU-8 filled in the CYTOP prism windows. A buffered oxide etchant is used to remove BOX parts under the interfaces. Some of the fabricated structures were tested, demonstrating the contribution of overlaying SU-8 prisms to the transmission efficiency of optical interconnections between fibers and SOI WGs.

This paper presents two facile methods to fabricate off-plane lenses made of SU-8, an epoxy-based negative photoresist from MicroChem, on glass for optical interconnection. The methods allow the fabrication of lenses with flexible spot size and focal length depending on SU-8 well size and SU-8 drop volume and viscosity. In the first method, SU-8 drops were applied directly into patterned SU-8 wells with Teflon-coated micropipettes, and were baked to become (a)-spherical lenses. The lens shape and size were mainly determined by SU-8 viscosity, ratio of drop volume to well volume, and baking temperature and time. In the second method, a glass substrate with SU-8 patterned wells was emerged in diluted SU-8, then drawn up and baked to form lenses. The lens shapes and sizes were mainly determined by SU-8 viscosity and well volume. By the two methods, SU-8 lenses were successfully fabricated with spot sizes varying in range from micrometers to hundred micrometers, and focal lengths varying in range of several millimeters, depending on the lens rim diameters and aspheric sag height. Besides, on-plane SU-8 lenses were fabricated by photolithography to work in conjunction with the off-plane SU-8 lenses. The cascaded lenses produced light spots reduced to several micrometers, and they can be applied as a coupler for light coupling from fiber/Light-emitting diode (LED) to microstructures and nanostructures. The results open up the path for fabricating novel optical microsystems for optical communication and optical sensing applications.

We propose an interdigitated Si lateral bipolar phototransistor integrated with an Al-SiO 2 -Al (metal-dielectric-metal structure) visible-blind ultraviolet Fabry-Perot bandpass filter. The maximum optical transmittance is 0.56 at the wavelength 332 nm, and the FWHM of transmission is 78.6 nm. And we successfully demonstrated suppression of visible light with the highest responsivity $\mathbf{9.78} \times \mathbf{10}^{-\mathbf{2}}$ (A/W) at wavelength of 350 nm.

A new Au-SiO2-Si stack grating structure to efficiently couple normally incident light to Au-Ge surface plasmon modes for enhancing Ge surface absorption is presented. Through an optimized design on the grating dimension, the surface plasmon modes are hybridized with a cavity mode for both suppressing light reflection and transmission to the Ge substrate. About 70% Ge absorption occurs in a 0.15-μm shallow layer near the Ge surface at the wavelength of 1.38 μm. Such a short absorption length is desirable for implementing a low-noised Ge avalanche photodiode.

The aim of PHOTONICS TECHNOLOGY LETTERS (PTL) is ultimately to serve the photonics community. As such, it is with great delight I would like to introduce the second Special Issue of PTL, in which we address the area of optical MEMS and nanophotonics, in response to a demand from the community. As with the inaugural Special Issue which appeared in November 2012, this Special Issue has been linked to an IEEE Photonics Society conference, this time the International Conference on Optical MEMS and Nanophotonics. The timescales for this Special Issue have been demanding and with this in mind, I would like to thank those who made rapid publication possible, namely the guest editors, authors, and anonymous reviewers for ensuring prompt reviewing, and Sylvia Flores and Eileen McGuinness for ensuring prompt production of the final manuscripts. I hope you will find this Special Issue of interest and hence, without further ado, I would like to hand over to the guest editors for the Special Issue on Optical MEMS and Nanophotonics and thank you for your continued readership.

A new operation scheme using optoelectronic tweezers and a locally confined dielectrophoresis to implement a tunable microsphere resonator coupled to a non-planar waveguide is presented. The optoelectronic tweezers are utilized to bring the microsphere to the waveguide while the dielectrophoretic force around the waveguide is exploited to finely tune the gap space between the microsphere and the waveguide in a liquid medium. Through these two mechanisms, we demonstrate a polyester microsphere can be freely moved to an SU-8 rib waveguide and operated in any of the coupling conditions by adjusting applied voltage.

This paper presents our recent studies on CMOS front-end circuits for high speed optical links. The circuit topologies of both transimpedance amplifier (TIA) and modulator driver (MD) are discussed for achieving wideband operation in PAM-4 modulation using advanced CMOS technology. Also, issues of integration of the circuits with silicon photonic devices such as the Ge-on-Si photo diode (PD) and silicon modulator are addressed for high performance silicon-based transceiver front-end of optical link.

We report a wafer-scale fabrication process to make large-area slot antenna arrays for studying spontaneous emission enhancement of 2D transition metal dichalcogenide. The experimental results show a 10-fold enhancement of photoluminescence was observed.

We present a butt-coupled Germanium (Ge) metal-semiconductor-metal photodetectors on silicon (Si) waveguides. This device is implemented by a novel process using self-aligned microbonding technique and rapid-melt-growth method for monolithically integrating single-crystal Ge and Si devices on the same plane. Through inserting a thin amorphous Si (a-Si) layer between the Ge and metal contact, the Schottky barrier height is modulated, which effectively reduces the dark current and increases the operation speed. The fabricated device shows a low dark current of 0.24 μA, a 3 dB bandwidth of 15 GHz and a responsivity of 0.25 A/W, at a bias voltage of -2.6 V for wavelength 1310 nm.

A silicon avalanche photodetector with a low breakdown voltage of -6.78 V is demonstrated by narrowing down the intrinsic layer width of interdigitated p-i-n junctions to ~ 150 nm. It reaches the physical limit of avalanche breakdown in which the performance degradation caused by the Zener tunneling process is negligible. Dark current at -4 V is measured, and a responsivity (gain) exceeding 1.424 A/W (110) at -6.75 V is obtained with an 850-nm laser illumination. The intrinsic bandwidth is determined to be 10 GHz, suggesting our device is applicable for a 10-Gb/s high-speed optical receiver application and beyond.

We present a chemical-biosensor in the Mid-IR range and based on cascaded porous silicon made on p- and n-type (100) silicon substrates of resistivities between 0.001 Ω cm and 0.005 Ω cm. The stacked porous layers of various porosities (20–80%) and thicknesses (5–9 μm) are formed by successive electrochemical etchings with different current densities. Working with FTIR technique that possesses fast response, high sensitivity, and capability of detecting and identifying functional groups, the cascaded porous structures provided enhanced refractive index sensitivities and reduced detection limits in chemical and biodetection. The largest wavenumber shifts were 50 cm−1/mM obtained for d -(+)-glucose and 96 cm−1/μg/mL for Cy5-conjungated Rabbit Anti-Mouse IgG. The lowest detectable concentration of glucose was 80 μM (1.4 mg/mL) with PS porosity of 40% and thickness of about 9 μm while it was 40 ng/mL for Cy5-conjugated Rabbit Anti-Mouse IgG which is 2.5×105 folds better than those in literature.

We present 3D simulation of low loss splitters made on Lithium Niobate used in Mach-Zehnder interferometers. The interferometer consists of the splitters designed with photonic crystal structures at splitting point and bend positions for reduced size and loss, and straight sections as channel waveguides with high electro-optical coefficient r33 of Lithium Niobate for reduced interactive length and modulating voltage π. The simulation shows a reduced coupling loss to 1.37 dB with the channel waveguides made suspended and Vπ?is only 0.42V for interactive length of 200 um.

A wideband optical mode converter is presented for coupling between fibers and sub-wavelength silicon photonic wires with large misalignment tolerance. This converter consists of a three-dimensional (3-D) SU-8 taper and silicon inverted nanotapers, which are cascaded and show coupling losses of 2.8 dB and 4.1 dB for the TE- and TM-polarized waves launched from a cleaved single mode fiber. The fiber misalignment tolerance for 3-dB transmittance drop is estimated to be $\pm {3}~\mu{\hbox {m}}$ .

For present-day optical communication systems, the commonly used normal-incidence photodetectors suffer from the tradeoff between bandwidth and quantum efficiency. Such a tradeoff is especially adverse for long wavelength communication systems operating at higher data rates. For example, the maximum responsivity for a commercially available 25 Gbps photodetector operating at 1310 nm wavelength is limited to less than 0.8 A/W. In this work, we design and demonstrate a high-speed, backside-incidence, critically-coupled Ge on SOI photodetector operating at 1310 nm while maintaining a high quantum efficiency. Our device is fabricated with RPCVD epitaxy, i-line lithography, silicide contact, and Al metal wire, which are fully compatible with the state-of-art CMOS process technology. With our epitaxial scheme and surface passivation method, a low bulk (surface) dark current density of 13 mA/cm2 (0.79 μA/cm) is measured from a ~ 700 nm thick Ge p-i-n device at -1 V bias. The responsivity at 1310 nm wavelength is measured to be 0.87 A/W, and the 3dB optical bandwidth of a 20 μm diameter device is measured to be 26 GHz. Our high-speed, backside-incidence, critically-coupled Ge on SOI photodetector may serve as a high-performance and low-cost solution for next generation high-speed optical receivers, and its benefit of decoupling bandwidth and quantum efficiency is especially prominent at higher data rates such as 40 Gbps and beyond.

We propose wavelength-selective infrared sensors made by multiple metallic resonant waveguide gratings integrated on a germanium photodetector array. The detective spectrum can cover from 1.25μm to 1.55μm with the FWHM less than 25nm.

A low-voltage dual-drive push-pull Si Mach-Zehnder modulator is demonstrated to implement an optical 25 Gbaud (50 Gb/s) PAM-4 transmission.

Nuclear Energy Agency of OECD has developed a methodology in the Safety Margin Action Plan (SMAP) to quantify the reduction of safety margin due to power uprate. The methodology combines the probabilistic and deterministic approaches of safety analyses. In the present study, the SMAP methodology is adopted to quantify the reduction of safety margin of a 5 % power uprate of Maanshan nuclear power plant (NPP) of Taiwan Power Company. The sequence selected to demonstrate the methodology is a medium break cold leg loss of coolant accident. An evaluation model code, RELAP5-3D/K is used in the LOCA analysis. Based on the plant specific PSA model, two dominant accident sequences of the medium LOCA are analyzed. Minimum success criterion of the PSA model is used. Phenomenon Identification and Ranking Table (PIRT) for parameters that are important for the medium break LOCA analyses and their distribution are identified. Two sets of calculations for each accident scenarios are performed to determine PCT at 102 and 105 % rated power. The data of the predicted PCTs are analyzed parametrically and nonparametrically (rank statistics) to determine PCT of the 95th percentile with 95 % of confidence. The results show that the nonparametric results always giving higher 95/95 PCT value and therefore, smaller safety margin. The change of safety margin after SPU is different for different accident scenarios. When the best estimated value is determined parametrically, the safety margin before power uprate is 12.3 and after power uprate is 11.8. There is 4.2 % reduction of safety margin when power is elevated from 102 to 105 % rated power. When the best estimated value is determined nonparametrically, the safety margin before SPU is 10.17 and after SPU is 10.42. The margin increases slightly after SPU. From these results, it can be concluded that the impact of SPU on the safety margin of PCT is very insignificant. The results also demonstrate that, among the parameters in PIRT, the parameter, PBOT, represents the axial power distribution has the largest impact on the predicted PCT. When the power distribution is bottom peaked, the predicted PCT is lower. It can be concluded that the steam cooling effect after core uncover plays a significant role in removing heat from the uncovered portion of the core.

A high-sensitivity biosensor is demonstrated by exploiting surface plasma (SP) enhanced transverse magneto-optical Kerr effect (TMOKE) on a packaged micro-optofluidic chip to implement a compact system for detecting chemical or biological objects. The SP grating made on a composite Au/Fe/Au layer exhibits a very dispersive Kerr parameter variation near the SP resonance wavelength. A preliminary experimental result on studying avidin-biotin interaction shows the sensitivity of avidin detection in PBS solution is about 31 nM.

A new technology using hydrogen annealing and thermal oxidation is proposed to fabricate a very compact 2-D multimode interference coupler monolithically integrated with two-layer silicon photonic wires. Two devices, a 1 × 1 cross-power coupler and a 1 × 22 power splitter, are presented and characterized. The experimental result shows that a 3-dB transmission bandwidth of 1.1 nm, and the on-chip coupler losses of 8.6 dB and 2.84 dB were accomplished for the 1 × 1 cross-power coupler and the 1 × 22 power splitter. This paper demonstrates the possibility of realizing 3-D photonic integration for silicon-on-insulator lightwave circuits.

A three-dimensional (3-D) adiabatic tapered coupler is demonstrated to improve light coupling between single-mode fibers (SMF) and an integrated photonic chip. This 3-D taper, made by polymer via a fabrication process using mode extrusion in combination with photolithography, can have a large coupling area matching with a fiber core. For a silicon oxynitride waveguide coupling to a SMF, the measured coupler loss was 3 dB. The fiber misalignment tolerance is 3.5 m and 3 to 5 m for the lateral and vertical offset, respectively, according to a 3-dB loss window.

Exploring the ordering mechanism and dynamics of self-assembled block copolymer (BCP) thin films under confined conditions are highly essential in the application of BCP lithography. In this study, it is aimed to examine the self-assembling mechanism and kinetics of silicon-containing 3-arm star-block copolymer composed of polystyrene (PS) and poly(dimethylsiloxane) blocks as nanostructured thin films with perpendicular cylinders and controlled lateral ordering by directed self-assembly using topographically patterned substrates. The ordering process of the star-block copolymer within fabricated topographic patterns with PS-functionalized sidewall can be carried out through the type of secondary (i.e., heterogeneous) nucleation for microphase separation initiated from the edge and/or corner of the topographic patterns, and directed to grow as well-ordered hexagonally packed perpendicular cylinders. The growth rate for the confined microphase separation is highly dependent upon the dimension and also the geometric texture of the preformed pattern. Fast self-assembly for ordering of BCP thin film can be achieved by lowering the confinement dimension and also increasing the concern number of the preformed pattern, providing a new strategy for the design of BCP lithography from the integration of top-down and bottom-up approaches.

Poor electron injection is a great concern for organic light emitting diodes (OLEDs). In order to improve the electron mobility, inserting organic superlattice structures in the electron transport layer was investigated in conventional OLEDs configuration. The superlattices are composed of alternating tris(8-hydroxyquinoline aluminium (Alq3) and copper phthalocyanine (CuPc) thin films, which are used as electron and hole injection layers. Experimental results show superlattices with a 6-nm period have the largest injected current. Reduction of turn-on voltage and resistance of superlattice OLEDs were also observed. After thermal annealing, the current-voltage characteristic changes and shows the possibility of layer intermixing in organic superlattices.

A single crystalline silicon microtoroidal resonator with integrated MEMS-actuated tunable optical coupler is demonstrated for the first time. It is fabricated by combining hydrogen annealing and wafer bonding processes. The device operates in all three coupling regimes: under-, critical, and over-coupling. We have also developed a comprehensive model based on time-domain coupling theory. The experimental and theoretical results agree very well. The quality factor (Q) is extracted by fitting the experimental curve with the model. The unloaded Q is as high as 110 000, and the loaded Q is continuously tunable from 110 000 to 5400. The extinction ratio of the transmittance is 22.4 dB. This device can be used as a building block of resonator-based reconfigurable photonic integrated circuits

A new plasmonic grating structure is proposed to implement Si near-infrared photodiodes through plasmon-induced hot carrier injection. The power conversion efficiencies (photon-to-plasmon) are near 70% and 90% at the wavelength of 851nm and 1305nm, respectively.

Near-infrared absorption at 2000-nm wavelength is observed in a Ge 1−x Sn x metal-semiconductor-metal (MSM) photodetector on a Si substrate. The device is fabricated by rapid melt growth method with graded Sn concentration up to 5–10%.

A new control mechanism to realize tunable microsphere resonators suspended in liquid is proposed. Via adjusting the bias voltage across an inhomogeneous dielectric structure (a rib waveguide plus microsphere), the microsphere resonator is attracted and levitated on top of the single-mode rib waveguide via an repulsive dielectrophoretic (DEP) force, where the coupling gap between the microsphere resonator and the waveguide is precisely controlled. The tunable gap spacing is analyzed by calculating the dielectrophoretic force through Maxwell stress tensor.

A GeSn metal-semiconductor-metal (MSM) photodetector is fabricated on a silicon-on-insulator (SOI) waveguide by rapid melt growth method. The Sn concentration of the GeSn photodetector is 2 % and shows a larger photo-responsivity by comparing with a pure Ge photodetector at long wavelength. The dark current is 3.7e-7 A at 5.4 V and the operation speed can be as high as 6.2 GHz.

This paper investigated the blue shift of photoluminescence and the changes of surface morphology of Alq 3 films by ionic argon plasma bombardment. Plasma with different conditions was applied to bombard thin Alq 3 films, modifying both the physical and chemical properties of the films. After characterizing Alq 3 films treated with different RF power by XPS, PL and AFM, we proposed the mechanisms to explain the absence of PL blue shift and chemical shift after the films were exposed in the air for more than 3 h. Experimental results showed that molecular structure damages would affect the bandgap of Alq 3 , leading to the blue shift effect. XPS results also showed that binding energy shifts are caused by enriched oxygen covalent bonds formed inside the films after plasma treatment. Also, surface roughness improves as RF power is increased.

A fast, effective process using hydrogen annealing is introduced to perform profile transformation on silicon-on-insulator (SOI) and to reduce sidewall roughness on silicon surfaces. By controlling the dimensions of as-etched structures, microspheres with 1 /spl mu/m radii, submicron wires with 0.5 /spl mu/m radii, and a microdisk toroid with 0.2 /spl mu/m toroidal radius have been successfully demonstrated on SOI substrates. Utilizing this technique, we also observe the root-mean-square (rms) sidewall roughness dramatically reduced from 20 to 0.26 nm. A theoretical model is presented to analyze the profile transformation, and experimental results show this process can be engineered by several parameters including temperature, pressure, and time.