This study demonstrates a high-performance capillary electrophoresis electrochemical (CE-EC) microchip featuring embedded the palladium nanoelectrode ensemble (Pd-NEE) as the decoupler. The Pd-NEE is fabricated utilizing a new composition of electroless plating bath for depositing palladium in the porous polycarbonate thin film. Palladium has the adsorbability and permeability to hydrogen, such that the produced Pd-NEE is able to eliminate the hydrogen formation from the high separation voltage and to reduce the background current for electrochemical detection. Moreover, this study adopts the oxygen plasma to etch the nanoelectrode ensemble to enlarge the exposed surface areas to further enhance the decoupling performance of the Pd-NRE. Experimental results show that the developed Pd-NEE decoupler is capable of decoupling the electrophoretic current such that the hydrogen formation on the electrochemical electrodes was suppressed. Results indicate the developed Pd-NEE decoupler greatly enhance the S/N ratio for the electrochemical signal and lower the detectable concentration for the bio-sample of the dopamine and catechol. The detection limit of dopamine and catechol are 50 nM and 100 nM using the microchip with the Pd-NEE decoupler. Furthermore, results also indicate that the palladium nanorod ensemble (Pd-NRE) decoupler produced using the oxygen plasma etching of Pd-NEE have better electrochemical detection performance in compared with the Pd-NEE decoupler. The background current of the electrochemical detection obtained with the microchip with Pd-NRE decoupler is about 5.6 pA at applied electric field of 800 V/cm electric field. In addition, combining the gold nanorod ensemble (GNRE) as the working electrode, the detection limit is lower to 10 nM and 50 nM, respectively. This study presents a high efficiency CE-EC microchip with a Pd-NRE decoupler and a GNRE working electrode which not only decreases the background current but improves the detection limit.

The purpose of this thesis is to fabricate 12-layer In0.75Ga0.25As quantum dot-in-a-well (In0.1Ga0.9As) structures grown by molecular-beam epitaxy (MBE) on GaAs substrate, and analyze the optical properties of laser devices for optical fiber communication systems. For the laser structures, larger Al content AlGaAs cladding layer enhance the optical confinement, but encounter much challenges to improve the quality. After we simulate and fabricate different Al content laser structures, we find the best cladding layer composition - Al0.2Ga0.8As which performs a best material gain. In the active layer, 12 layers In0.75Ga0.25As quantum dots (QDs) and QDs in a well (DWell) structure, and DWell with Be-doping in the well structure are included in this study. The well structure slows down the hot carriers speed and Be-doping decrease the carrier life time and increases the electron-hole pair recombination rate. We increase the QDs deposition coverage to move the emission wavelength to 1.3£gm, but the high temperature cladding layer growth process indirectly anneal the QDs and result in the emission wavelength blue shift to 1.24£gm. In the laser fabrication, to transport the light wave in smaller dispersion loss single mode waveguide, wet etching photolithography processes are adapted in this study to fabricate 2£gm width ridge waveguide. The as-cleaved facets are used as Fabry-Perot laser mirrors in ridge waveguide lasers. Finally, the current density of QD Laser(C528) lasing in CW mode is 581A/cm2, slope efficiency of 510mW/A and maximum power/facet of 65mW are obtained.Then the current density of DWELL+PD Laser(C540) lasing in CW mode is 880A/cm2, slope efficiency of 430mW/A and maximum power/facet of 34mW are obtained.

The purpose of this thesis is to fabricate 12-layer InxGa1-xAs quantum dots grown on 2-nm In0.1Ga0.9As quantum wells (DWell) laser structures grown by molecular-beam epitaxy (MBE) on GaAs substrats. We expect to optimum the lasers performance by tune the epitaxial recipe and fabrication condition. For the carrier injection efficiency, DWell structure of quantum dots grown on quantum wells is proposed to enhance the carrier capture rate. So we analyze a series of DWell structure in this work. In the epitaxial recipe, we investigate the influences of p-type doping and change the quantum wells growth temperature for the laser structures. In the laser fabrication, to transport the light wave in smaller dispersion loss single mode waveguide, dry etching photolithography processes are adapted in this study to fabricate 2.2mm width ridge waveguide. The as-cleaved facets are used as Fabry-Perot laser mirrors in ridge waveguide lasers. The pattern can be transferred effectively with less under-cut by dry etching compare with wet etching. Finally, the P-type doping DWell laser exhibits high power/facet of 24mW, slope efficiency of 0.209W/A. The maximum power/facet of PWell580 laser reach to 24mW, slope efficiency of 0.238W/A after raising the growth temperature to 580oC.

Abstract In this thesis, we propose a new geometrical structure of waveguide for the application of traveling-wave electroabsorption modulator (TWEAM). As approaching to high-speed performance in TWEAM, low parasitic capacitance in the waveguide is necessary to get good microwave propagation properties. In this work, a novel processing called two-step undercut-etching the active region (UEAR) is developed to reduce the parasitic capacitance. First of all, Beam Propagation Method (BPM) is used to calculate this 2-D structure optical modes ensuring the guiding capability in such kind of waveguides. Based on an equivalent circuit model, the microwave propagation on different structures of waveguide is then investigated to decide the UEAR waveguide structure. By the selectively etching solution on InP/InGaAsP, the processing by two-step UEAR is developed to reduce the parasitic capacitance in the waveguide core. H3PO4:HCl is used to selectively etch P-InP layer on the top of InGaAsP M.Q.W. (multiple quantum wells, active region). H3PO4:H2O2:H2O is subsequently and selectively remove InGaAsP M.Q.W.s to define the waveguide core. This processing has been successfully developed. The electrical transmission measurement on this kind of TWEAM shows low reflection S11 of < -17.5dB and a low insertion loss S21 of < ¡V2.7dB from D.C. to 40GHz, indicating high microwave performance on such two-step UEAR waveguide can be achieved due to the low parasitic capacitance.

Recently, there are great demands for RF band pass filters with smaller size/volume, lighter weight, and higher performance for advanced mobile/wireless communication system. However, fabricated RF filters using traditional lumped element, dielectric resonators, or surface acoustic wave¡]SAW¡^filters have difficulties in on-chip integration, power handling capability, and temperature compensation. Alternatively, thin-film bulk acoustic wave resonator¡]FBAR¡^filters are very suitable devices for MMIC¡¦s since they can be fabricated on Si or GaAs substrates at a lower magnitude than lumped elements or dielectric resonators, plus they have a much lower insertion loss and higher power handling capabilities than surface acoustic wave devices and full integration with other CMOS RF IC circuitry for realizing a goal of system on chip¡]SOC¡^. In their simplest form, practical FBARs consist of a sputtered piezoelectric thin film sandwiched between top and bottom electrodes onto which an electric field is then applied. An FBAR must have two acoustically reflecting surfaces in order to trap energy and produce resonating characteristics. For this purpose, the thin film bulk acoustic resonator has to be isolated acoustically from the substrate. In view of this, in order to obtain a high Q factor and reduce spurious responses, this paper proposed the air gap type resonator using the sacrificial layer etching. The thickness of the AlN thin film used for piezoelectric thin film of Air-gap FBAR is 1um. Pt/Ti with 3000&#x00C5;/300&#x00C5; thickness is used as the top and bottom electrode. The device has a resonance frequency of 1.2GHz, and S11-paparameter of -25dB is also obtained.

By integrating Nanotechnology and MEMS technology, this thesis aims to research a flexural-plate wave (FPW) sensor for testing Immunoglobulin E (IgE) concentration in blood serum, a significant index for the diagnosis of allergies. The traditional methods of blood assay are time-consuming and costly, and its average accuracy of only 60-70 percent. After compare the major four kinds of acoustic sensor, the FPW sensor demonstrates a high accuracy, high sensitivity, low operation frequency, low diagnosis time and low cost. This thesis utilizes a reactive RF sputter system to deposite the piezoelectric ZnO thin film. To obtain the high C-axis orientation (002) characteristic of ZnO membrane, many parameters such as substrate temperature, Ar/O2 ratio and RF power have been adjusted and optimized during the sputtering process. The effects of varied parameters will be investigated and analysis by using SEM or XRD facilities. In this study, we combined the high figure-of-merits ZnO deposition techniques and single-side anisotropic silicon etch process to implement the process integration of FPW device. Finally, this research has demonstrated a 50-60MHz center frequency can be extracted from such silicon-based FPW microsensor.

A simple and high efficient wet etching technique for fabricating pyramid textures on (100) Si wafer is proposed. Conventionally, pyramid textures were formed on Si wafers to reduce reflections using KOH anisotropic etching. Isopropyl Alcohol (IPA) is often added to the solution to abate the bubbling effect caused by hydrogen released form the Si surfaces during reaction. In this study, a metal net with proper opening dimension was used as a shelter to trap the hydrogen from leaving the surfaces of Si, and therefore turns the hydrogen gas into a gas-type etching mask during the anisotropic etching. In this way, pyramid textures with dimensions range from 3&#x00B5;m to 8&#x00B5;m were successfully fabricated. The measured average reflectivity of the texture for incident optical wave length from 400nm to 1000nm is less than 18%.

No description available.

The objective of this thesis is to apply semiconductor etching process technologies on 6 inch P-type Si substrate and produce a mold of Light Guiding Plate (LGP). After evaporate chromium (Cr) onto the Si substrate as etch mask, the thin films were then patterned and subsequently etch by plasma. Different powers were used to compare the cross-sections of the patterns. The results would be the references of Si molding process. Another objective is to fabricate Si-V grooves which can connect the fibers and accurately position fibers. Anisotropic etching of Si-V grooves were formed using EDP solution, and sputtered Ta2O5 was used as the etch mask. At a etching temperature of 1100C, the under cut is 2.5~3mm . Additionally using SiO2 as etch mask by thermo evaporation at 1050¢J .Use EDP solution at 1100C, the under cut is 2.25mm which had a better result.

Thesis (Ph.D.)--University of Melbourne, Melbourne Dental School, Faculty of Medicine, Dentistry and Health Sciences, 2010. / Typescript. Includes bibliographical references.