Enhancement in ferroelectricity in V-doped ZnO thin film grown using laser ablation

ABSTRACT We report evidence of enhancement in ferroelectricity in thin films of vanadium (V) doped ZnO grown at higher oxygen pressure. This process reduces oxygen deficiency and the material becomes very insulating, which in turn lowers the leakage current through the ferroelectric capacitor. 2 at. % V doped ZnO films, with thickness of approximately 1 µm were grown epitaxially on c-cut sapphire (Al 2 O 3 ) (0001) at a growth temperature of 600°C. X-ray analysis showed the layers to be epitaxial where the (0002) diffraction peak had a rocking curve FWHM below 1°. The films with higher oxygen pressure were more insulating than the one grown with lower oxygen pressure. The saturation polarization doubled when the growth pressure increased from 300 mT to 500 mT. Time gated ICCD imaging of the ablated plasma during various O 2 pressures and how it translated to the film quality are presented

Final report submitted to the US Department of Energy (8/15/96 to 8/14/00). [Experimental and theoretical investigation of dual laser ablation for stoichiometric large-area multi-component film growth]

This research involves a systematic study of the dual-laser ablation process to understand the underlying mechanisms of the process, and to investigate the applicability of this technique to the growth of multi-component thin films. In this study, time-of-flight ion probe, emission spectroscopy, and species resolved CCD imaging methods have been used as in-situ diagnostic techniques to investigate experimentally the effect of the process parameters on the plasma ionization, ion spatial distribution, species velocity distribution profiles and expansion profiles for single component systems as well as individual elements of the multi-component material system Cu(InGa)Se{sub 2}. A theoretical model that is consistent with the experimental observations has been developed. Following tasks outlined in the proposal were successfully completed in the time period 8/15/96 to 8/14/00

Two-dimensional optical filter and associated methods

An optical filter includes an input optical fiber bundle and an output fiber bundle. Each of the bundles has one end having the fiber ends substantially two-dimensionally arrayed and another end substantially linearly arrayed. Each input fiber is configured to receive a portion of a two-dimensional input image at the two-dimensional end and transmit the image portion to the one-dimensional end. A spectrally dispersive element receives the image portions from the input fiber bundle and outputs a predetermined spectral component to the output optical fiber bundle at the one-dimensional end, transmitting the image portion to the two-dimensional end. The output fiber bundle two-dimensional ends are arrayed in corresponding fashion to the first ends of the input fibers for spatially reconstructing the input image

Clathrate compounds and method of manufacturing

The present invention comprises new materials, material structures, and processes of fabrication of such that may be used in technologies involving the conversion of light to electricity and/or heat to electricity, and in optoelectronics technologies. The present invention provide for the fabrication of a clathrate compound comprising a type II clathrate lattice with atoms of silicon and germanium as a main framework forming lattice spacings within the framework, wherein the clathrate lattice follows the general formula Si136-yGey, where y indicates the number of Ge atoms present in the main framework and 136-y indicates the number of Si atoms present in the main framework, and wherein y\u3e0

Method of manufacturing a clathrate compound

The present invention comprises new materials, material structures, and processes of fabrication of such that may be used in technologies involving the conversion of light to electricity and/or heat to electricity, and in optoelectronics technologies. The present invention provide for the fabrication of a clathrate compound comprising a type II clathrate lattice with atoms of silicon and germanium as a main framework forming lattice spacings within the framework, wherein the clathrate lattice follows the general formula Si136−yGey, where y indicates the number of Ge atoms present in the main framework and 136−y indicates the number of Si atoms present in the main framework, and wherein y\u3e0

Activated reactive laser deposition of GeO, films

Amorphous GeO, optical thin films were grown in an oxygen ambient on heated Si substrates using the technique of pulsed laser deposition. The application of a partially ionized oxygen plasma generated by passing the plume through a ring electrode facilitated stoichiometric film growth in low O2 partial pressures. Emission spectroscopy of the plume revealed an enhancement in the ionic and neutral excited Ge species. The concentration of excited neutral and ionic oxygen atoms also significantly increased when the ring electrode was activated at P(O.-J>lO mTorr. Coupling the results of the film property measurements with the emission studies suggested that the presence of 0 atoms near the substrate surface during tilm growth was more critical in promoting oxidation than the gas phase process in the plume. The low-pressure conditions that were utilized to deposit stoichiometric film growth identified the appropriate conditions to produce uniform films over a large area that may be suitable for waveguide fabrication

Synthesis and Characterization of Bulk and Thin Film Clathrates for Solid State Power Conversion Applications

Abstract Thin films of the type I clathrate Ba 8 G

Photopolymerization-based Synthesis of Iron Oxide Nanoparticle Embedded PNIPAM Nanogels for Biomedical Applications

Conventional therapeutic techniques treat patients by delivering biotherapeutics to the entire body. With targeted delivery, biotherapeutics are transported to the afflicted tissue reducing exposure to healthy tissue. Targeted delivery devices are minimally composed of a stimuli responsive polymer allowing triggered release and magnetic nanoparticles enabling targeting as well as alternating magnetic field (AMF) heating. Although more traditional methods, like emulsion polymerization, have been used to realize such devices, the synthesis is problematic. For example, surfactants preventing agglomeration must be removed from the product increasing time and cost. Ultraviolet (UV) photopolymerization is more efficient and ensures safety by using biocompatible substances. Reactants selected for nanogel fabrication were N-isopropylacrylamide (monomer), methylene bis-acrylamide (crosslinker), and Irgacure 2959 (photoinitiator). The 10 nm superparamagnetic nanoparticles for encapsulation were composed of iron oxide. Herein, a low-cost, scalable, and rapid, custom-built UV photoreactor with in situ, spectroscopic monitoring system is used to observe synthesis. This method also allows in situ encapsulation of the magnetic nanoparticles simplifying the process. Nanogel characterization, performed by transmission electron microscopy, reveals size-tunable nanogel spheres between 40 and 800 nm in diameter. Samples of nanogels encapsulating magnetic nanoparticles were subjected to an AMF and temperature increase was observed indicating triggered release is possible. Results presented here will have a wide range of applications in medical sciences like oncology, gene delivery, cardiology, and endocrinology

Photopolymerization-based synthesis of iron oxide nanoparticle embedded PNIPAM nanogels for biomedical applications

Conventional therapeutic techniques treat patients by delivering biotherapeutics to the entire body. With targeted delivery, biotherapeutics are transported to the afflicted tissue reducing exposure to healthy tissue. Targeted delivery devices are minimally composed of a stimuli responsive polymer allowing triggered release and magnetic nanoparticles enabling targeting as well as alternating magnetic field (AMF) heating. Although more traditional methods, like emulsion polymerization, have been used to realize such devices, the synthesis is problematic. For example, surfactants preventing agglomeration must be removed from the product increasing time and cost. Ultraviolet (UV) photopolymerization is more efficient and ensures safety by using biocompatible substances. Reactants selected for nanogel fabrication were N-isopropylacrylamide (monomer), methylene bis-acrylamide (crosslinker), and Irgacure 2959 (photoinitiator). The 10 nm superparamagnetic nanoparticles for encapsulation were composed of iron oxide. Herein, a low-cost, scalable, and rapid, custom-built UV photoreactor with in situ, spectroscopic monitoring system is used to observe synthesis. This method also allows in situ encapsulation of the magnetic nanoparticles simplifying the process. Nanogel characterization, performed by transmission electron microscopy, reveals size-tunable nanogel spheres between 40 and 800 nm in diameter. Samples of nanogels encapsulating magnetic nanoparticles were subjected to an AMF and temperature increase was observed indicating triggered release is possible. Results presented here will have a wide range of applications in medical sciences like oncology, gene delivery, cardiology, and endocrinology