For the reliable applications of silver nanowires, AgNW, which is used as a conductive transparent film in electronic devices, the isothermal degradation behaviors of AgNW films with and without overcoating were investigated. Accelerated isothermal degradation was performed as a function of temperature, time, and atmosphere. Electrical resistance and optical transmittance were measured and correlated with the microstructural damages, such as formation of oxide particles and fragmentations of AgNW, which were quantitatively determined from the scanning electron micrographs. The overcoating retarded the formation of oxide particles and subsequent fragmentations as well as resulting degradation in electrical resistance without affecting the optical transmittance.
Size-dependent dynamic instability of cylindrical nanowires incorporating the effects of Casimir attraction and surface energy is presented in this research work. To develop the attractive intermolecular force between the nanowire and its substrate, the proximity force approximation (PFA) for small separations, and the Dirichlet asymptotic approximation for large separations with a cylinder-plate geometry are employed. A nonlinear governing equation of motion for free-standing nanowires – based on the Gurtin-Murdoch model – and a strain gradient elasticity theory are derived. To overcome the complexity of the nonlinear problem in hand, a Garlerkin-based projection procedure for construction of a reduced-order model is implemented as a way of discretization of the governing differential equation. The effects of length-scale parameter, surface energy and vacuum fluctuations on the dynamic instability threshold and adhesion of nanowires are examined. It is demonstrated that in the absence of any actuation, a nanowire might behave unstably, due to the Casimir induction force.
In this paper, a low power highly sensitive Triple Metal Surrounding Gate (TM-SG) Nanowire MOSFET photosensor is proposed which uses triple metal gates for controlling short channel effects and III–V compound as the channel material for effective photonic absorption. Most of the conventional FET based photosensors that are available use threshold voltage as the parameter for sensitivity comparison but in this proposed sensor on being exposed to light there is a substantial increase in conductance of the GaAs channel underneath and, thereby change in the subthreshold current under exposure is used as a sensitivity parameter (i.e., Iillumination/IDark). In order to further enhance the device performance it is coated with a shell of AlxGa1-xAs which effectively passivates the GaAs surface and provides a better carrier confinement at the interface results in an increased photoabsorption. At last performance parameters of TM-SG Bare GaAs Nanowire MOSFET are compared with TM-SG core-shell GaAs/AlGaAs Nanowire MOSFET and the results show that Core-Shell structures can be a better choice for photodetection in visible region.
In our studies the absorption, transmittance and reflectance spectra for periodic nanostructures with different parameters were calculated by the FDTD (Finite-Difference Time-Domain) method. It is shown that the proportion of reflected light in periodic structures is smaller than in case of thin films. The experimental results showed the light reflectance in the spectral range of 400–900 nm lower than 1% and it was significantly lower in comparison with surface texturing by pyramids or porous silicon.
Silicon nanowires on p-type Si substrate were formed by the Metal-Assisted Chemical Etching method (MacEtch). At solar cells with radial p-n junction formation the thermal diffusion of phosphorus has been used at 790°C. Such low temperature ensures the formation of an ultra-shallow p-n junction. Investigation of the photoelectrical properties of solar cells was carried out under light illumination with an intensity of 100 mW/cm2. The obtained parameters of NWs' solar cell were Isc = 22 mA/cm2, Uoc = 0.62 V, FF = 0.51 for an overall efficiency η = 7%. The relatively low efficiency of obtained SiNWs solar cells is attributed to the excessive surface recombination at high surface areas of SiNWs and high series resistance.