Study on optical band gap of boron-doped nc-Si : H film

The optical band gap (E-g) of the boron (B)-doped hydrogenated nano-crystalline silicon (nc-Si:H) films fabricated using plasma enhanced chemical vapor deposition (PECVD) was investigated in this work. The transmittance of the films were measured by spectrophotometric and the E-g was evaluated utilizing three different relations for comparison, namely: alphahnu=C(hnu-E-g)(3), alphahnu=B-0(hnu-E-g)(2), alphahnu=C-0(hnu-E-g)(2). Result showed that E-g decreases with the increasing of Boron doping ratio, hydrogen concentration, and substrate's temperature (T-s), respectively. E-g raises up with rf power density (P-d) from 0.45W.cm(-2) to 0.60w.cm(-2) and then drops to the end. These can be explained for E-g decreases with disorder in the films.

Improvement of thin silicon on sapphire (SOS) film materials and device performances by solid phase epitaxy

The increased emphasis on sub-micron CMOS/SOS devices has placed a demand for high quality thin silicon on sapphire (SOS) films with thickness of the order 100-200 nm. It is demonstrated that the crystalline quality of as-grown thin SOS films by the CVD method can be greatly improved by solid phase epitaxy (SPE) process: implantation of self-silicon ions and subsequent thermal annealing. Subsequent regrowth of this amorphous layer leads to a greater improvement in silicon layer crystallinity and channel carrier mobility, evidenced, respectively, by double crystal X-ray diffraction and electrical measurements. We concluded that the thin SPE SOS films are suitable for application to high-performance CMOS circuitry. (C) 2000 Elsevier Science S.A. All rights reserved.

Strain-induced morphological evolution and preferential interdiffusion in SiGe epitaxial film on Si(100) during high-temperature annealing

Strain relaxation in initially flat SiGe film on Si(1 0 0) during rapid thermal annealing is studied. The surface roughens after high-temperature annealing, which has been attributed to the intrinsic strain in the epilayers. It is interesting to find that high-temperature annealing also results in roughened interface, indicating the occurrence of preferential interdiffusion. It is suggested that the roughening at the surface makes the intrinsic strain in the epilayer as well as the substrate unequally distributed, causing preferential interdiffusion at the SiGe/Si interface during high-temperature annealing. (C) 1999 Elsevier Science B.V. All rights reserved.

Aluminum induced crystallization of strongly (111) oriented polycrystalline silicon thin film and nucleation analysis

A polycrystalline silicon thin film was fabricated on glass substrate by means of aluminum induced crystallization (AIC). Al and alpha-Si layers were deposited by magnetron sputtering respectively and annealed at 480A degrees C for 1 h to realize layer exchange. The polycrystalline silicon thin film was continuous and strongly (111) oriented. By analyzing the structure variation of the oxidation membrane and lattice mismatch between gamma-Al2O3 and Si, it was concluded that aluminum promoted the formation of (111) oriented silicon nucleus by controlling the orientation of gamma-Al2O3, which was formed at the early stage of annealing.

Fluorescence Hydrogen Peroxide Probe Based on a Microstructured Polymer Optical Fiber Modified with a Titanium Dioxide Film

A highly sensitive microstructured polymer optical fiber (MPOF) probe for hydrogen peroxide was made by forming a rhodamine 6G-doped titanium dioxide film on the side walls of array holes in an MPOF. It was found that hydrogen peroxide only has a response to the MPOF probe in a certain concentration of potassium iodide in sulfuric acid solution. The calibration graph of fluorescence intensity versus hydrogen peroxide concentration is linear in the range of 1.6 x 10(-7) mol/L to 9.6 x 10(-5) mol/L. The method, with high sensitivity and a wide linear range, has been applied to the determination of trace amounts of hydrogen peroxide in a few real samples, such as rain water and contact lens disinfectant, with satisfactory results.

Cellulose acetate polymer film modified microstructured polymer optical fiber towards a nitrite optical probe

A novel microstructured polymer optical fiber (MPOF) probe for nitrites (NO(2)(-)) detection was made by forming rhodamine 6G (Rh 6G)-doped cellulose acetate (CA) on the side wall of array holes in a MPOF It was found that the MPOF probe only have a response to nitrites in a certain concentration of sulfuric acid solution The calibration graph of fluorescence intensity versus nitrites concentration was linear in the range of 2.0 x 10(-4) g/ml-5.0 x 10(-3) g/ml. The method possesses case of chemical modification, low cost design, and potential for direct integration with existing instrumentation, and has been applied to the determination of nitrites in real samples with satisfactory results. (C) 2010 Elsevier B.V. All rights reserved

Precursor Film in Dynamic Wetting, Electrowetting, and Electro-Elasto-Capillarity

Dynamic wetting and electrowetting are explored using molecular dynamics simulations. The propagation of the precursor film (PF) is fast and obeys the power law with respect to time. Against the former studies, we find the PF is no slip and solidlike. As an important application of the PF, the electro-elasto-capillarity, which is a good candidate for drug delivery at the micro- or nanoscale, is simulated and realized for the first time. Our findings may be one of the answers to the Huh-Scriven paradox and expand our knowledge of dynamic wetting and electrowetting.

Peeling behavior of a bio-inspired nano-film on a substrate

A peeling model is proposed to analyze the peeling properties of bio-mimetic nano-films using the finite element method (FEM) and theoretical approach. The influences of the nano-film's adhesion length, thickness, elastic modulus, roughness and peeling angle on the peeling force were considered as well as the effect of the viscoelastic behavior. It has been found that the effective adhesion length, at which the peeling force attained maximum, was much smaller than the real length of nano-films; and the shear force dominated in the case of smaller peeling angles, whereas, the normal force dominated at larger peeling angles. The total peeling force decreased with an increasing peeling angle. Two limiting values of the peeling-off force can be found in the viscoelastic model, which corresponds to the smaller and larger loading rate cases. The effects of nano-film thickness and Young's modulus on peeling behaviors were also discussed. The results obtained are helpful for understanding the micro-adhesion mechanisms of biological systems, such as geckos. (C) 2010 Elsevier Ltd. All rights reserved.

LOCAL BENDING OF THIN FILM ON VISCOUS LAYER

Effects of deposition layer position and number/density on local bending of a thin film are systematically investigated. Because the deposition layer interacts with the thin film at the interface and there is an offset between the thin film neutral surface and the interface, the deposition layer generates not only axial stress but also bending moment. The bending moment induces an instant out-of-plane deflection of the thin film, which may or may not cause the so-called local bending. The deposition layer is modeled as a local stressor, whose location and density are demonstrated to be vital to the occurrence of local bending. The thin film rests on a viscous layer, which is governed by the Navier-Stokes equation and behaves like an elastic foundation to exert transverse forces on the thin film. The unknown feature of the axial constraint force makes the governing equation highly nonlinear even for the small deflection case. The constraint force and film transverse deflection are solved iteratively through the governing equation and the displacement constraint equation of immovable edges. This research shows that in some special cases, the deposition density increase does not necessarily reduce the local bending. By comparing the thin film deflections of different deposition numbers and positions, we also present the guideline of strengthening or suppressing the local bending.

Experimental study of Electro-elasto-capillarity:Electric field driven unwrapping of water drop with elastic film

<正>Elasto-capillarity has drawn much of scientists' attention in the past several years.By inducing electric field into the droplet,the encapsulation and release procedure can be realized and we call it electro-elasto-capillarity(EEC).EEC offers a novel method for micro-scale actuation and self-assemble of moveable devices.It also provides a good candidate for the drug delivery at micro- or nanoscale.