Search

Using the high working pressure plasma-enhanced chemical vapor deposition (HWP-PECVD) technique, the hydrogenated microcrystalline silicon (μc-Si:H) films for photovoltaic layers of thin film solar cells was investigated. The μc-Si:H films were deposited on surface textured fluorine-doped tin oxide (FTO) glass substrates at 100 Torr in a 100 MHz very high frequency (VHF) plasma of gas mixtures containing He, H, and SiH. It was found that an optimum ratio of the H/SiH flow-rate existed for growing a homogenous microcrystalline through the whole film without amorphous incubation layer. When an intrinsic μc-Si:H thin film was deposited at n-i-p single junction solar cell, the cell performances were dependent on with or without an amorphous incubation layer. With an amorphous incubation layer, the open circuit voltage ( V) of cell was 0.8 V, which was typical cell property of hydrogenated amorphous silicon (a-Si:H). On the other hand, at the optimum ratio of the H/SiH flow-rate, μc-Si:H single cell responding an infrared light showed the V of 0.4 V. [ABSTRACT FROM AUTHOR]

Highly ordered TiO nanotubes with 85 μm length were fabricated by the electrochemical method for 17 h at 60 V in an ethylene glycol/0.5 % NHF/5 % water mixture solution. The nanotube arrangements and surface morphologies of the anodic titania films were clearly dependent on the electrolytes used in the fabrication process. The activation energy for the transformation from an amorphous to anatase structure was evaluated using differential scanning calorimetry (DSC) results and a Kissinger plot. The activation energy for anatase transformation on the anodic titania nanotubular film was estimated to be 208.9 kJ/mol. [ABSTRACT FROM AUTHOR]

The effect of annealing on the interfacial adhesion energy between electroless-plated Ni films and polyimide substrates was evaluated using a 180-degree peel test. The measured peel strength values decrease from 263.6 ± 7.8 J/m to 109.3 ± 6.4 J/m after annealing for 100 h at 200 °C in an ambient environment. XPS analysis on the peeled surfaces reveals that the peeling is due to cohesive failure inside the polyimide, which is related to the fact that wet treatment produces an activated bonding mechanism between electroless-plated Ni and polyimide. This implies a degradation of the polyimide structure due to oxygen diffusion through the interface between Ni and alkali wet-treated polyimide, which is also closely related to the decrease in the interfacial adhesion energy due to thermal treatment in ambient conditions. [ABSTRACT FROM AUTHOR]

Rapid progress in nanotechnology has made it increasingly easier to nanostructure metal materials. This paper describes the formation of uniform silver nanowires by reducing silver acetate with PLLA polymer. The silver nanowires were prepared by wetting a porous template at 350 °C using 1.5 wt.% CH2Cl2 solution containing PLLA/silver acetate in a ratio of 1:1. A thermal analysis in the temperature range of 100 °C to 400 °C was carried out by a differential scanning calorimeter (DSC). An exothermic reaction peak associated with pure silver occurred at 352 °C at a heating rate of 5 °C/min. From the attenuated total reflectance (ATR) spectra analysis of the silver and PLLA composites, it was obtained that the absorption peak of the PLLA became weak by heating to successively higher temperatures in the range of 230 °C to 350 °C. The DSC and ATR results showed that the PLLA can be directly and easily removed at 350 °C, leaving the pure metal inside the pores. The silver nanowires consisted of nanoparticles whose average diameter was about 26.5 nm. And those nanowires with an aspect ratio of about 13 showed an UV-vis absorption peak, which is attributed to the surface plasmon excitation at 350 nm and 377 nm. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) molybdenum disulphide (MoS2) atomic layers have a strong potential to be used as 2D electronic sensor components. However, intrinsic synthesis challenges have made this task difficult. In addition, the detection mechanisms for gas molecules are not fully understood. Here, we report a high-performance gas sensor constructed using atomic-layered MoS2 synthesised by chemical vapour deposition (CVD). A highly sensitive and selective gas sensor based on the CVD-synthesised MoS2 was developed. In situ photoluminescence characterisation revealed the charge transfer mechanism between the gas molecules and MoS2, which was validated by theoretical calculations. First-principles density functional theory calculations indicated that NO2 and NH3 molecules have negative adsorption energies (i.e., the adsorption processes are exothermic). Thus, NO2 and NH3 molecules are likely to adsorb onto the surface of the MoS2. The in situ PL characterisation of the changes in the peaks corresponding to charged trions and neutral excitons via gas adsorption processes was used to elucidate the mechanisms of charge transfer between the MoS2 and the gas molecules. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) molybdenum disulphide (MoS2) atomic layers have a strong potential to be used as 2D electronic sensor components. However, intrinsic synthesis challenges have made this task difficult. In addition, the detection mechanisms for gas molecules are not fully understood. Here, we report a high-performance gas sensor constructed using atomic-layered MoS2 synthesised by chemical vapour deposition (CVD). A highly sensitive and selective gas sensor based on the CVD-synthesised MoS2 was developed. In situ photoluminescence characterisation revealed the charge transfer mechanism between the gas molecules and MoS2, which was validated by theoretical calculations. First-principles density functional theory calculations indicated that NO2 and NH3 molecules have negative adsorption energies (i.e., the adsorption processes are exothermic). Thus, NO2 and NH3 molecules are likely to adsorb onto the surface of the MoS2. The in situ PL characterisation of the changes in the peaks corresponding to charged trions and neutral excitons via gas adsorption processes was used to elucidate the mechanisms of charge transfer between the MoS2 and the gas molecules. [ABSTRACT FROM AUTHOR]