Semiconductor nanocrystals are expected to play an important role in the development of new generation of microelectronic and photonic devices such as light emitting diodes and memory elements. Optimization of these devices requires detailed investigations. Various spectroscopic techniques have been developed for material and devices characterization. This study covers the applications of the following techniques for the analysis of nanocrystalline materials: Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, X-Ray Diffraction (XRD) and X-Ray Photoelectron (XPS). Transmission Electron Microscopy (TEM) and Secondary Ion Mass Spectrometry (SIMS) are also used as complementary methods. Crystallinity ratio, size, physical and chemical environment of the nanostructures were probed with these methods. Si and Ge nanocrystals were formed into the oxides Al2O3 and SiO2 by ion implantation, magnetron sputtering and laser ablation methods. FTIR and XPS are two methods used to extract information on the surface of the nanocrystals. Raman and XRD are non destructive and easy-to-operate methods used widely to estimate the crystallinity to amorphous ratio and the sizes of the nanocrystals. In this study, the structural variations of SiO2 matrix during the formation of Si nanocrystals were characterized by FTIR. The shift in position and changes in intensity of the Si-O-Si asymmetric stretching band of SiOx was monitored. An indirect metrology method based on FTIR was developed to show the nanocrystal formation. Ge nanocrystals formed in SiO2 matrix were investigated using FTIR, Raman and XRD methods. FTIR spectroscopy showed that Ge atoms segregate completely from the matrix at relatively low temperatures 900 oC. The stress between the Ge nanocrystals and the matrix can vary in samples produced by magnetron sputtering if the production conditions are slightly different. Si and Ge nanocrystals were formed into Al2O3 matrix by ion implantation of Si and Ge ions into sapphire matrix. Raman, XRD, XPS and TEM methods were employed to characterize the formed nanocrystals. XRD is used to estimate the nanocrystal sizes which are in agreement with TEM observations. The stress on nanocrystals was observed by Raman and XRD methods, and a quantitative calculation was employed to the Si nanocrystals using the Raman results. XPS and SIMS depth profiles of the sample implanted with Si, and annealed at 1000 oC were measured. Precipitation of Si atoms with the heat treatment to form the nanocrystals was observed using XPS. The volume fraction of the SiOx shell to the Si core in Si nanocrystals was found to be 7.9 % at projection range of implantation.

After hydrolyzing zinc acetate in methanol solution, spherical ZnO nanoparticles in the size range from about 2.5 to 5 nm were synthesized by maintaining a ZnO concentration of 0.02M. Compared to ZnO nanoparticles prepared via other methods, the particles prepared using our novel colloidal chemistry exhibit narrow size distribution and a high sensitivity to the surrounding environment. The structure and composition of the white powders precipitated from the colloidal solution can vary, depending on how the powder samples are prepared. Factors such as desorption and adsorption of methanol, binding of water and exposure to humid air have been studied to correlate to the structure and composition observed from the precipitated powder. Methanol desorption rate and excess KOH on the particle surface have played an important role in the structural changes. Furthermore, upon annealing, the white precipitate is recovered to wurtize ZnO. XRD and TEM are used to study the structural transformation of ZnO nanoparticles.

The thesis consists of eight chapters of which the first chapter presents a brief overview of inorganic nanostructures. Synthesis and magnetic properties of MnO and NiO nanocrystals are described in Chapter 2, with emphasis on the low-temperature ferromagnetic interactions in these antiferromagnetic oxides. Chapter 3 deals with the synthesis and characterizations of nanocrystals of ReO3, RuO2 and IrO2 which are oxides with metallic properties. Pressure-induced phase transitions of ReO3 nanocrystals and the use of the nanocrystals for carrying out surface-enhanced Raman spectroscopy of the molecules form Chapter 4. Use of ionic liquids to synthesize different nanostructures of semiconducting metal sulfides and selenides is described in Chapter 5. Synthesis of Mn-doped GaN nanocrystals and their magnetic properties are described in Chapter 6. A detailed investigation has been carried out on the growth kinetics of nanostructures of a few inorganic materials by using small-angle X-ray scattering and other techniques (Chapter 7). The study includes the growth kinetics of nanocrystals of Au, CdS and CdSe as well as of nanorods of ZnO. Results of a synchrotron X-ray study of the formation of nanocrystalline gold films at the organic-aqueous interface are also included in this chapter. Chapter 8 discuses the use of the organic-aqueous interface to generate Janus nanocrystalline films of inorganic materials where one side of the film is hydrophobic and other side is hydrophilic. This chapter also includes the formation of nanostructured peptide fibrils at the organic-aqueous interface and their use as templates to prepare inorganic nanotubes.

Aim of this work was, to investigate the preparation of Si NC memories by sputter deposition. The milestones are as follows: - Review of relevant literature. - Development of processes for an ultrathin tunnel-oxide and high quality sputtered SiO2 for use as control-oxide. - Evaluation of methods for the preparation of an oxygen-deficient silicon oxide inter-layer (the precursor of the Si NC layer). - Characterization of deposited films. - Establishment of techniques capable of probing the phase separation of SiOx and the formation of Si NC. - Establishment of annealing conditions compatible with the requirements of current CMOS technology based on experimental results and simulations of Si NC formation. - Preparation Si NC memory capacitors using the developed processes. - Characterization of these devices by suitable techniques. Demonstration of their memory functionality.

Thesis (Ph.D.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Chemical and Materials Engineering, Medical Sciences - Biomedical Engineering. Title from pdf file main screen (viewed on January 30, 2010). Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

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Semiconductor nanocrystals, otherwise known as Quantum dots (Q dots), are a new type of fluorophore that demonstrates many advantages over conventional organic fluorophores. These advantages offer the opportunity to improve known immunofluorescent methods and immunofluorescent biosensors for rapid and portable bacterial detection in water. The detection of the micro organism Escherichia coli O157:H7 by attenuation of a fluorophore’s signal in water was evaluated alone and in the presence of another bacterial species. A sandwich immunoassay with antibodies adhered to SU-8 as a conventional comparison to our novel attenuation detection was also conducted. The assays were tested for concentration determination as well as investigation for cross reactivity and interference from other bacteria and from partial target cells. In order to immobilize the capture antibodies on SU-8, an existing immobilization self-assembly monolayer (SAM) for glass was modified. The SAM was composed of a silane ((3-Mercaptopropyl) trimethoxysilane (MTS)) and hetero-bifunctional cross linker (N-γ-maleimidobutyryloxy succinimide ester (GMBS)) was utilized in this procedure. The SU-8 surface was activated using various acids baths and oxygenated plasma, and it was determined that the oxygenated plasma yielded the best surface attachment of antibodies. The use of direct fluorophore signal attenuation for detection of the target E. coli resulted in the lowest detectable population of 1x10¹ cfu/mL. It was not specific enough for quantitative assessment of target concentration, but could accurately differentiate between targeted and non-targeted species. The sandwich immunofluorescent detection on SU-8 attained the lowest detectable population of 1x10⁴ cfu/ml. The presence of Klebsiella pneumoniae in solution caused some interference with detection either from cross reactivity or binding site blocking. Partial target cells also caused interference with the detection of the target species, mainly by blocking binding sites so that differences in concentration were not discernable. The signal attenuation not only had a better lowest detectable population but also had less measurement error than the sandwich immunoassay on SU-8 which suffered from non-uniformed surface coverage by the antibodies.

Synthesis and characterization of optical nanocrystals and nanostructures. An approach to transparent laser nanoceramicsMontserrat Galceran MestresEls materials nanocristal·lins són materials policristal·lins amb una mida de partícula en el rang dels nanòmetres. Presenten diferents propietats físiques, òptiques, electròniques, químiques i estructurals perquè tenen una proporció més elevada d'àtoms a la superfície que els materials en volum. La síntesi de nanocristalls és la primera etapa per fabricar materials nanoceràmics per a aplicacions làser. Són atractius per a làsers en estat sòlid perquè ofereixen avantatges com ara: baix cost, fabricació senzilla i bones propietats mecàniques i òptiques.Aquesta tesi tracta la síntesi i caracterització de nous nanomaterials òptics (KRE(WO4)2, RE2O3, KTiOPO4) dopats amb ions actius com les terres rares (RE), erbi, iterbi, holmi i europi com a primera etapa per sintetitzar noves ceràmiques làser Ho:Lu2O3. Per avaluar les qualitats d'aquests materials com a possibles làser en estat sòlid o materials d'òptica nolinear, s'ha dut a terme una caracterització estructural, òptica i espectroscòpica aquests nanomaterials (nanocristalls, nanoestructures i nanoceràmiques).Synthesis and characterization of optical nanocrystals and nanostructures. An approach to transparent laser nanoceramicsMontserrat Galceran MestresNanocrystalline materials are polycrystalline materials with a particle size in the nanometer range that have different physical, optical, electronic, chemical and structural properties because they have a larger fraction of surface atoms than larger-scale materials. The synthesis of nanocrystals is the first step in manufacturing nanoceramic laser materials; they are very attractive to solid state laser due to several advantages such as low cost, easy fabrication and good mechanical and optical properties.This thesis deals with the synthesis and characterization of new optical nanomaterials (KRE(WO4)2, RE2O3, KTiOPO4) doped with active rare earth (RE) ions as erbium, ytterbium, holmium and europium as a first step to synthesize a new Ho:Lu2O3 laser ceramics. An extensively structural, optical and spectroscopic characterization of the nanomaterials (nanocrystals, nanostructures and nanoceramics) was performed in order to evaluate these materials as a promising solid state laser or nonlinear optical materials.