We report both the growth of carbon nanotube forests and electrical conduction on W, Ti, and TiN substrates coated with an ultra-thin Al2O3 support layer. Varying the Al2O3 thickness, a good electrical contact and high nanotube density is possible for a 0.5 nm Al2O3 layer as such an ultra-thin film allows tunnelling. X-ray photoelectron spectroscopy shows that, when using these non-continuous Al2O3 films, Fe catalyst diffuses into the conducting substrates, eventually causing growth to stop. Forests grown on ultra-thin Al2O3 are potentially useful for applications as interconnects, supercapacitors, and heat spreaders.
ZnO nanowires have been grown by chemical vapour deposition (CVD) using PdZn bimetallic nanoparticles to catalyse the process. Nanocatalyst particles with mean particle diameters of 2.6 ± 0.3 nm were shown to catalyse the growth process, displaying activities that compare well with those reported for sputtered systems. Since nanowire diameters are linked to catalyst morphology, the size-control we are able to exhibit during particle preparation represents an advantage over existing approaches in terms of controlling nanowire dimensions, which is necessary in order to utilize the nanowires for catalytic or electrical applications.(See supplementary material 1)
ZnxSnyOz thin films (<100nm thickness), deposited by remote sputtering from a metal target using a confined argon plasma and oxygen gas jet near the sample, were investigated for their material properties. No visible deformation or curl was observed when deposited on plastic. Materials were confirmed to be amorphous and range between 5 and 10 at.% Sn concentration by x-ray diffraction, x-ray photoemission spectroscopy and energy-dispersive x-ray spectroscopy. Factors affecting the material composition over time are discussed. Depletion of the Sn as the target ages is suspected.
All-chemical vapor deposited silicon nitride / monolayer graphene TFTs have been fabricated. Polychromatic Raman spectroscopy shows high quality monolayer graphene channels with uniform coverage and significant interfacial doping at the source-drain contacts. Nominal mobilities of approximately 1900 cm 2 V -1 s -1 have been measured opening up a potentially useful platform for analogue and RFR-based applications fabricated through allchemical vapor deposition processes.Graphene is a one atomic thick layer of carbon atoms, where their sp 2 bonds are arranged in a honeycomb crystal lattice. It is being touted as the new "miracle material" for electronics and photonics in the 21 st Century. This is because of its unique properties such as the very high carrier mobility at room temperature, large free mean path for ballistic transport, high Young's modulus and near zero-gap semiconductor (semi-metal). These make it potentially unique for nano-electronics, biosensors and information and computer technologies. Early graphene transistor configurations consisted of back-gated metal-oxide-semiconductor field effect transistors. Alternative top-gate configurations include the use of channels formed from high-quality natural and Kish exfoliated graphene, CVD grown and polymer transferred graphene and epitaxial deposited samples. SiO 2 , Al 2 O 3 , and HfO 2 have been investigated as viable dielectrics in zero band gap devices. Graphene transistors exhibit linear transfer characteristics without saturation or weakly saturate followed by a secondary linear regime [1]. Due to the low on/off current ratio, graphene-based devices are unsuitable for logic applications through various routes to bandgap opening have been proposed, such as the use of sub-5 nm-wide nanoribbons [2], mechanically strained free-standing channels, and biased bilayers [3].The dielectric is known to affect the charge carrier type in graphene devices [4]. SiN x has been successfully used as a dielectric for TFTs within flat-panel displays for many years, yielding a mature and widely accepted technology, which is, for example, routinely used in a-Si backplanes for organic light-emitting diode displays [5]. In this work, we show TFTs based on monolayer graphene as the active channel material with SiN x as the insulator where both materials have been produced using chemical vapor deposition (CVD) processes. Though low on/off ratios mitigate against their use in logic circuits they are well suited for analog RF applications, in body area networks and some flat panel applications.Bottom gated graphene TFTs were produced on 300 nm thick SiN dielectric layers deposited by PECVD onto degenerately doped silicon substrates. SiN x was deposited at 150 o C using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) 10.1149/05008.0217ecst ©The Electrochemical Society ECS Transactions, 50 (8) 217-221 (2012) 217 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.59.222.12 Downlo...
Zinc oxide (ZnO) nanowires (NWs) are receiving significant industrial and academic attention for a variety of novel electronic, optoelectronic and MEMS device applications due to their unusual combination of physical properties, including being optically transparent, semiconducting and piezoelectric. Hydrothermal growth is possible at significantly lower temperatures (and hence lower thermal budgets) compared with other NW growth methods, such as chemical vapour deposition. In this context, the hydrothermal growth of ZnO NWs on seeded substrates immersed in equimolar zinc nitrate/HMTA aqueous solution was investigated. NWs were grown on polished silicon (001) substrates, and the solution concentrations, temperatures and growth times were varied. Importantly, the NW diameter was found to depend only on concentration during hydrothermal growth for times up to 4 hours. The average diameter was 14 nm in 0.005 M solution and increased up to a maximum 150 nm at 0.07 M, when the NWs formed a continuous polycrystalline film. Concentration and temperature were all found to affect the axial growth rate of NWs in the [0001] direction. The growth rate was constant up to 4 hours (200 nm hr -1 ) for constant conditions (81 o C, 0.025 M). The growth rate was found to increase approximately linearly with concentration at a rate of 7840 nm M -1 hr -1 up to 0.06 M (81 o C solution). The growth rate also increased linearly with temperature at a rate of 4.9 nm hr -1 K -1 (0.025 M solution). This indicates that growth takes place close to the equilibrium point, found by linear regression to be 36 o C for 0.025 M solution.
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