Projects Synthesis Materials Fabrication Devices Characterization Theory
Copper oxide ( CuO and Cu2O )   Vanadium dioxide (VO2)  
Nickel Oxide (NiO)   Silver nanosheet  
Vanadium Pentoxide (V2O5)   Zinc Oxide (ZnO)  
Zinc Sulfide (ZnS)   Iron Oxide (Fe3O4)  
Copper oxide ( CuO and Cu2O )
Cuprous oxide (Cu2O) and Cupric oxide (CuO) both exist in nature as cuprite and tenorite respectively.Cupric oxide, CuO, is a p type semiconductor with a narrow band gap of 1.2 eV while Cu2O is also p type semiconductor with a direct forbidden band gap of 2.17 eV.

Both materials have various interesting applications such as electronic cathode materials, photonics , catalysts, gas sensors, FE emitters, solar cells etc.

Amongst the various existing morphology of CuO and Cu2O such as flowers, cubes, nanobelts etc. 1-Dimensional morphology like nanowires and nanorods have gained much attention because these constitutes an important building blocks of nanodevices and integrated nanosystems. Therefore synthesis of 1-D CuO and Cu2O have become an important topic of research. In literature many methods such as thermal oxidation & decomposition, microwave irradiation, sonochemical, sol gel, hydrothermal route, template assisted synthesis are well documented. But the preparation of these CuO material systems either requires high temperatures, sophisticated instrumentation, inert atmosphere or long reaction times etc. Therefore in the present study efforts will be made to synthesize single crystalline CuO and Cu2O nanowires by a simple and inexpensive wet chemical method. Among the available transition metal oxides, such as Ni, Co, Zn and Fe, Cu2O has gained considerable research interest because it is a promising candidate for the solar cell applications. Therefore the Cu2O nanowires synthesized in the present work will be further utilized in the fabrication of solar cells.
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Vanadium dioxide (VO2)
The focus is currently on synthesizing single crystalline well-faceted VO2 nanowires. The synthesis is performed via vapor phase transport by thermal chemical vapor deposition (CVD).

Vanadium dioxide (VO2) exhibits thermochromism via a semiconductor-to-metal phase transition at a critical temperature of 68F, accompanied by drastic changes in electrical resistivity and optical properties. VO2 also undergoes a Mott metal-insulator transition (MIT) close to room temperature. Raman studies on VO2 nanowires reveal the MIT mechanism may be based upon electron-electron correlation.

Accompanying this MIT is a small structural distortion of the underlying VO2 lattice from a low-temperature monoclinic (semiconducting phase) to a high-temperature tetragonal rutile (metallic phase) structure.


Vanadium dioxide nanowires grown by thermal chemical vapor
deposition (CVD) on an r-plane sapphire substrate. In this case,
VO2 nanowires grow perpendicular with respect to the substrate.

This figure is a SEM image of a VO2 nanowire as grown on a sapphire substrate (r-plane sapphire). The final goal is to grow high purity VO2 nanowires with a diameter of approximately 50 nm.
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Nickel Oxide (NiO)
In recent years, much attention has been paid to the development of resistive random access memory (ReRAM) due to its excellent memory characteristics such as low power operation, high density integration, and high-speed write and erase operations. Various binary oxide materials such as NiO, TiO2, CuO, FeO, PCMO, and SrTi2O3 have been extensively studied for their potential application in nonvolatile ReRAM.

We focus NiO material for ReRAM device. We attempt to synthesize single crystalline NiO nanowires using thermal CVD technique. We attempt to observe resistance switching behavior from these single crystalline NiO nanowires to elucidate its mechanism.

We study spin-coatable NiO electron beam resist development for ReRAM application. We have attempted to realize nanostructures of NiO using electron beam lithography. If we use NiO electron beam resist, we can fabricate various shape and size NiO, so we can study about size dependent and shape dependent.


NiO with wire morphology


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Silver nanosheet
In this work, we present a facile method to synthesize silver nanosheets, chainlike sheets and microwires via decomposition of the AgNO3 in ethanol in the presence of ammonia. The experiments show that the concentration of ammonia, reaction temperature and time are important factors for controlling the morphology of the products. On the base of our experimental results, we propose an ammonia-tuning Oswald ripening mechanism to elucidate the formation of different morphologies of silver structures such as the nanosheets, chainlike sheets, and microwires. The current-voltage characteristic of the individual silver microwire shows linear behavior, and the electrical conductivity of the silver microwire is found to be comparable to that of the bulk silver materials, indicating that it can serve as interconnects in fabricating the micro/nanodevices.
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Vanadium Pentoxide (V2O5)
As a positive electrode active material in secondary battery usable for overcoming V2O5 problem, such as poor electronic conductivity and low melting point, nanocomposites comprising of V2O5/RuO2 obtained via a simple chemical route. V2O5/RuO2, nanocomposites has been proposed in the hope of improving its melting point, chemical inertness, superior hardness, and better electrical conductivity due to the presence of ruthenium dioxide shell, which are required for a high performance positive electrode in secondary battery. Owing to these features of our composites according to our approach, a lithium-ion secondary battery having an excellent charge-discharge cycle characteristic may be obtained. In this work we will develop a facile synthetic route suitable for large scale positive active electrode material production.

This may open up a great opportunity to develop a secondary battery with high performance charge-discharge cycle durability.
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Zinc Oxide (ZnO)
Zinc oxide is wide-band gap semiconductor and has a wide range of applications as transparent electrodes in various optoelectronic devices, gas sensors and as heat mirrors in solar collectors. The doping of ZnO broadens the application range in optoelectronic devices fabrication. Although interesting nanostructures can be produced via sol gel, hydrothermal, and CVD techniques, but future incorporation into nanoscale devices would suffer from a major drawback, the instability to position the nanostructures with nanoscale precision greatly impedes device design. Electron beam nanolithography offer the possibility to solve this drawback using the conventional liftoff technique to pattern Indium-doped Zinc oxide. The electron beam lithography technique shows a great promise as a versatile patterning tool applicable for transparent electrode and sensor applications. We synthesize ZnO by thermal CVD (nanowires) and electron beam lithography (direct-write patterns of any shape).
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Zinc Sulfide (ZnS)
Nanostructured materials have become an intense area of research due to its applicability in interdisciplinary fields. Nanomaterials have made impact not only in miniaturization of electronic devices but their quantum size effect has led to their applications in areas like quantum dot lasers, biological labels, bar codes, single electron transistors and light emitters etc. In addition, unique properties such as high fluorescence quantum yield and photochemical stability makes the QDs-LEDs as potential candidate for flat panel displays and lightings. Amongst II-VI semiconductor materials, ZnS finds applications in novel optical and electronic devices like multilayer dielectric filters, light emitting diodes, cathodoluminescent applications etc. In order to use these nanoparticles particularly in device application it is essential to have as low a size distribution as possible and should remain thermally stable without coagulation during the device operation. Therefore in the present work monodispersed and narrow size distributed ZnS nanoparticles stabilized with thioglycerol (TG) molecules have been chemically synthesized. These nanoparticles will be further utilized for the fabrication of ITO/ PEDOT:PSS (poly(3,4-ethylenedioxythiophene ) poly(styrene sulfonate) / PVK poly (N-vinylcarbazole)/ZnS/Au heterostructure device and its current-voltage characteristics will be measured.
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Iron Oxide (Fe3O4)
Magnetite, Fe3O4, is an extensively studied material because of several interesting properties and its many applications, such as magnetic recording media or spin-valve. However, forming functional magnetite nano- and microstructures suitable for those viable applications still remains a challenge due to the technical limitations associated with the fabrication process. We have successfully developed a novel electron beam and/or photosensitive resist suitable for direct writing of functional nano- and microstructures using a sol-gel based process. This method eliminates the problems associated with the lift-off process that is typically performed when a conventional organic resist is used. This technique shows great promise as a versatile patterning tool applicable for magnetic recording media or spin-valve applications.
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