SiON is a suitable material for the implementation of photonic integrated circuits with a middle refractive index contrast
for the visible and near infrared region. The paper presents the design, fabrication and characterization of SiON/SiO2/Si
structures for passive optical waveguides realization with designed refractive index contrast 0.13. This refractive index
contrast allows fabrication of strip SiOx/SiON/SiO2/Si waveguides with waveguide band losses bellow 0.01dB/cm at
150um waveguide radius. SiON and SiOx layers were fabricated by plasma-enhanced chemical vapor deposition
techniques. The plasma-enhanced chemical vapor deposition technological parameters were tuned and optimized
for designed refractive index contrast 0.13 and designed waveguide thickness 2.5 m. The refractive index of fabricated
SiON layers were measured by optical ellipsometry.
KEYWORDS: Gallium arsenide, Microelectromechanical systems, Gas sensors, Temperature sensors, Resistance, Etching, Thermal effects, 3D modeling, Temperature metrology, Bulk micromachining
This work describes the design, simulation, fabrication and characterization of a TiN/Pt microheater prepared on GaAs
micromechanical structure as a prospective device for MEMS gas sensor array. We use the electro-thermal simulation to
verify the properties of the designed microstructure, which conformed achievement of the operating temperatures in the
range of 200 to 320°C with heating power less than 25 mW. The average temperature gradient in the active area does not
exceed 0.6 K/μm. We demonstrated the fabrication of GaAs suspended membranes, realized in two steps, by
combination of surface and bulk micromachining. We also describe the development and characterization of a
microheater on a GaAs membrane. The power consumption at an operating temperature of approximately 550 K is about
30 mW and the achieved thermal resistance value is 8.43 K/mW.
Bismuth film electrodes (BiFEs) have a potential to replace toxic mercury used most frequently for determination of
heavy metals (Cd, Pb, Zn) by anodic stripping voltammetry. We prepared a graphite disc electrode (0.5 mm in diameter)
from a pencil-lead rod and developed a nitrogen doped diamond-like carbon (NDLC) microelectrode array consisting of
50 625 microdiscs with 3 &mgr;m in diameter and interelectrode distances of 20 &mgr;m on a highly conductive silicon substrate
as a support for BiFEs. The disc graphite BiFE was used for simultaneous determination of Pb(II), Cd(II) and Zn(II) by
square wave voltammetry (SWV) in an aqueous solution. We found the optimum bismuth-to-metal concentration ratio in
the solution to be 20. The dependence of the stripping responses on the concentration of target metals was linear in the
range from 1×10-8 to 1.2×10-7 mol/L. Detection limits 2.4×10-9 mol/L for Pb(II), 2.9×10-9 mol/L for Cd(II) and 1.2×10-8 mol/L for Zn(II) were estimated. A bismuth-plated NDLC microelectrode array was used for Pb(II) determination by
differential pulse voltammetry (DPV) in an aqueous solution. We found that the stripping current for bismuth-plated
NDLC array was linear in the concentration range of Pb(II) from 2×10-8 to 1.2×10-7 mol/L. The detection limit 2.2×10-8
mol/L was estimated from a calibration plot.
Planar microelectrochemical chips with thin film electodes of different shapes and arrangement, have been developed and fabricated. Micro electrochemical cell with closely vertically spaced electrodes allows to exploit the effect of redox recycling and an increase of collection efficiency for a high current amplification. PC simulations of electro- mechanical properties of sl-BLM is useful tool for evaluation and prediction of BLM behavior. Non-symmetric microelectrode arrays were designed and fabricated for electrical monitoring of human skin.
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