In the current study, we used a high-speed camera system with particle image velocimetry to observe the internal fluidity of water droplets during sliding. The droplets' velocity during sliding was controlled by slipping and rolling motions. On the superhydrophobic surface, with a contact angle of 150 degrees, the droplet fell at high velocity by slipping. However, on a normal hydrophobic surface whose water contact angle was around 100 degrees, both slipping and rolling controlled the droplet's velocity during sliding. In addition, the advancing velocity might be large when the slip velocity is large and the contact area is small.

No abstract

No abstract

Articles you may be interested inBand offsets of metal-oxide-semiconductor capacitor with HfLaTaO/HfSiO stacked high-k dielectric J. Vac. Sci. Technol. B 31, 022204 (2013); 10.1116/1.4792843Fabrication of advanced La-incorporated Hf-silicate gate dielectrics using physical-vapor-deposition-based in situ method and its effective work function modulation of metal/high-k stacks Band bendings of Si substrates have been observed using hard x-ray photoemission spectroscopy. With a capability of collecting photoelectrons generated as deep as 40 nm, the binding energy shift in a core level caused by the potential profile at the surface of the substrate results in a spectrum broadening. The broadening is found to be significant when heavily doped substrates are used owing to its steep potential profile. The surface potential of the substrate can be obtained by deconvolution of the spectrum. This method has been applied to observe the band bending profile of metal-oxide-semiconductor capacitors with high-k gate dielectrics. By comparing the band bending profiles of heavily-doped n + -and p + -Si substrates, the interface dipoles presented at interfaces can be estimated. In the case of W gated La 2 O 3 / La-silicate capacitor, an interface dipole to shift the potential of −0.45 V has been estimated at La-silicate/Si interface, which effectively reduces the apparent work function of W. On the other hand, an interface dipole of 0.03-0.07 V has been found to exist at Hf-silicate/ SiO 2 interface for W gated HfO 2 / Hf-silicate/ SiO 2 capacitor.

No abstract

Grating couplers are proposed for polarization-independent coupling of light between a single-mode fiber and a 220-nm-thick channel waveguide on silicon-on-insulator. The grating couplers have nonuniform grating periods that are composed of the intersection or union of a set of two near-optimal TE- and TM-grating periods. The proposed grating couplers have a coupling efficiency greater than 20% and polarization dependent loss (PDL) lower than 0.5 dB within 3-dB bandwidth in design. For the evaluation of the design concept, a fabricated intersection grating coupler has the PDL of less than 0.8 dB within the wavelength range of 1540 to 1560 nm, and the coupling efficiency is ∼18%.

No abstract

Pentacene organic thin-film transistors (OTFTs) using La x Nb (1Àx) O y as gate dielectric with different La contents (x ¼ 0.347, 0.648) have been fabricated and compared with those using Nb oxide or La oxide. The OTFT with La 0.648 Nb 0.352 O y as gate dielectric can achieve a high carrier mobility of 1.14 cm 2 V À1 s À1 (about 1000 times and 2 times those of the devices using Nb oxide and La oxide, respectively), and has negligible hysteresis of À0.130 V, small sub-threshold swing of 0.280 V/ dec, and low threshold voltage of À1.35 V. AFM and XPS reveal that La can suppress the formation of oxygen vacancies in Nb oxide while Nb can alleviate the hygroscopicity of La oxide, which results in a more passivated and smoother dielectric surface, leading to larger pentacene grains grown and thus higher carrier mobility. The OTFT with Nb oxide has an anticlockwise hysteresis but the device with La oxide shows an opposite direction. This can be explained in terms of donorlike traps due to oxygen vacancies and acceptor-like traps originated from hydroxyl ions formed after La 2 O 3 absorbing water moisture. V