Hydrogen ion-sensitive field effect transistor with sol-gel-derived La-modified lead titanate gate Department of Electrical Engineering, National Sun Yat-Sen University *Jen-Fu Su **Ying-Chung Chen Abstract In this thesis the amorphous lead lanthanum titanate (Pb1-xLaxTi1-x/4O3, PLT) membrane has been prepared by sol-gel method as a novel pH-sensitive layer. The lead lanthanum titanate membrane was directly deposited on the SiO2(1000Å)/p-Si substrate by spin-on coating to form the PLT/SiO2/Si EIS structure. The C-V measurement was used for examining the fabrication parameters and sensing properties. Moreover, the PLT membrane was grown onto the SiO2 gate ISFET as the PLT/SiO2 gate ISFET. The electrical properties with the different parameter conditions can be obtained by the I-V measurement. Experimental results show that the fabrication parameters and characteristics of the PLT membrane are determined at the La-modified content about 3 mol% and the firing temperature of 400¢J via the EIS structure. There exhibits the pH response of about 44-52 mV/pH in the range of pH 2-12. Furthermore, the nonideal factors, such as drift of 0.1-0.3 mV/h, hysteresis of 2-13 mV and lifetime decay of about 72 mV/pH-day, can be also obtained via the I-V properties of the ISFET. Finally, the hardware architecture of pH measuring system has been built up. The system makes use of constant current and voltage bias technique to ensure that the variations of the output voltage can give directly the variations of pH value. For the purpose of achieving the function of data calibration and driving the liquid crystal display (LCD), the 8051 microprocessor is employed. Keywords: ISFET, Sol-gel, Lead lanthanum titanate, Drift, Hysteresis, pH meter * Student ** Advisor

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Zirconia is a metal oxide with high band gap. It is commonly used as catalysts in many industrial practices. In recent years, its high-energy-gap value and redox properties also render it as an excellent photocatalyst, which can eliminate or reduce a variety of pollutants. The purpose of this work is to prepare and characterize the chromium-doped ordered porous zirconia. The main purpose of doping chromium into the zirconia is to avoid the Martensitic transformation of zirconia under high temperatures by volume change and pore structure change, thus reducing the cracking and inferior mechanical properties. With emulsion-free polymerization for the synthesis of polystyrene (PS) particles, controlling the particle diameter less than 200 nm is possible. A polystyrene template is thus produced by gravity sedimentation of these PS particles. Final Cr-doped zirconia is obtained by infiltration of a precursor solution, a mixture consisting of zirconium n-propoxide, n-propanol, acetylacetone, and chromium (III) nitrate nonahydrate, into the PS template, followed by drying and calcination at elevated temperatures. A systematic study on the pore structure and physical properties by XRD and Raman is conducted by varying the precursor concentration, the calcination temperature, and the dopant concentration. The results show that, unlike the pure zirconia, the pore structure of Cr-doped zirconia remains stable under higher calcination temperatures. Without any phase transformation, the doped Cr, evidenced from the EDS mapping, tends to help stabilize the zirconia at tetragonal phase. The average surface area and pore diameter of Cr-doped zirconia from BET measurement are 19 ~ 21 m2/g and 25 -45 nm, far better than the bulk zirconia. The improved surface properties are also confirmed by SEM observations.

Unter Nutzung des Sol-Gel-Prozess von Siliciumalkoxiden wurden dünne Schichten präpariert. Um eine Funktionalisierung derartiger SiO2-Schichten zu erhalten, wurden einem auf Tetraethoxysilan basierenden Sol Aldehyde, Hydroxycarbonsäuren bzw. Amino-carbonsäuren zugesetzt. Alternativ zu Additiven wurden Alkyltriethoxysilane eingesetzt. Neue azomethinhaltige Siliciumprecursoren wurden synthetisiert und direkt oder im Gemisch mit Tetraethoxysilan hydrolisiert und auf ihre Eignung hinsichtlich der Schichtpräparation getestet. Der Einfluss der Modellsubstanzen auf die Kinetik des Sol-Gel-Prozesses, die Schichtzusammensetzung und die Schichteigenschaften, wird durch die Kombination spektroskopischer und oberflächen-analytischer Methoden aufgeklärt. Für eine Prüfung der erzielten Funktionalisierung wurden die verschieden modifizierten Solsysteme zur Immobilisierung des Enzyms Glucose-Oxidase eingesetzt und die erzielten Enzymaktivitäten systematisch verglichen.

Thèse de doctorat : Chimie : Tours : 2008. / Titre provenant de l'écran-titre.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1973. / Includes bibliographical references (p. 137-142).

Thesis (doctoral)--Rheinisch-Westfälische Technische Hochschule Aachen, 1994.

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A sol-gel stationary phase was developed for in-situ infrared (IR) detection of analytes on thin-layer chromatography (TLC) plates. These sol-gel-based TLC plates have improved optical properties compared with conventional TLC plates in IR spectroscopic analysis. Samples can be analyzed in transmission geometry, requiring no special attachments. The sol-gel-based TLC plates demonstrate significantly better light throughput and a wider spectral range than conventional TLC plates analyzed in diffuse reflectance geometries.The sol-gel precursor, methyltrimethoxyorthosilicate (MTES), was templated with cetyltrimethylammonium bromide (CTAB) and urea in order to form a porous sol-gel. Aerosol deposition was used to apply the sol-gel solution onto either glass slides or silicon wafers within an enclosed chamber. Many variables were studied to determine their effect on the quality of the sol-gel stationary phases, including the ratio of MTES:methanol:water:CTAB:urea:HCl:, gelation times and temperatures, and deposition rate. Sol-gel films prepared using MTES/methanol/water/CTAB at ratios of 1 : 20 : 7 : 0.2 containing 5 wt% urea (relative to MTES) and pH 1.5 were crack-free, mechanically stable, and uniform in appearance. The films were tens of microns thick with a highly interconnected porous structure.For chromatographic separations, the films exhibited good solvent migration velocity and could be repeatedly washed and reused for TLC separations without showing degradation in the separation. Several different classes of compounds, including polyaromatic hydrocarbons and dyes, were successfully separated. Theoretical plate values measured on the MTES-based sol-gel films were comparable to those obtained on commercially available TLC plates.

The manipulation of molecular structures is an important enabling technology for future advances in nanotechnology. The ability to control the synthesis of nanostructured materials, such as the bond formation and geometry of a molecule is of great significance to nanoscience as nanosystems are constructed from these smaller units. Influencing the assembly of molecular structures at the early stages of material formation can modify the ensuing molecular aggregate structure with the potential for impact in a broad range of optical, chemical, and biological applications. Heteroleptic titanium metal alkoxides (OPy)₂Ti(4MP) ₂ and (OPy)₂Ti(TAP)₂, where OPy = OC₆H₆N, 4MP = OC₆H₄(SH)-4, and TAP = OC₆H₂(CH₂N(CH₃)₂)₃-2,4,6 were investigated as precursors for thin film and solution-based synthesis of oxide materials via the photoactivation of intermolecular reactions (e.g. hydrolysis/condensation) at selected ligand sites about the metal center. Manipulation of the molecular structure of these photosensitive metal alkoxides was achieved through the use of optical irradiation parameters, such as the tuning of the excitation wavelength, total optical fluence, and pulse energy intensity. Irradiating these metal alkoxides with UV-light was seen to cause photodisruption in the ligand groups leading to the formation of Ti-O-Ti linking via hydrolysis and condensation reactions. In spin-coated (OPy)₂Ti(TAP)₂ films, these photoinduced bridge bond formations resulted in an increase in refractive index and film densification as well as produced an insoluble film when rinsed in pyridine. By making use of these photoinduced film properties, the formation of physical relief structures from spin-coated (OPy)₂Ti(TAP)₂ films was demonstrated along with the ability to photopattern sub-micron and nanometer features. In addition, the micro- and nanostructure of thin films were optically manipulated through several deposition methods; a novel dip-coated in-situ photodeposition technique was utilized by illuminating at specific distances above the meniscus to further control the early stages of material formation due to changes in the mobility of the reactants from the evaporation and gravitational draining of the solvent. The ability to manipulate molecular development at the on-set of material formation through different deposition techniques and optical parameters allowed for the creation of several thin film optical devices, such as gratings, micro-optic lenslet arrays, and binary "on-off" patterned devices.