Effect of deuterium on passivation of Si surfaces

A properly passivated silicon surface is chemically stable, and all interface properties are constant. The freshly etched Si surface is full of dangling bonds resulting in high surface activity and instability. Hydrogen treatment is a proper procedure to decrease the number of dangling bonds. We demonstrated that deuterium adsorbs on Si surface at room temperature much stronger than hydrogen. Moreover, in case of deuterium-passivated wafers the vacuum storage can be omitted without risking the non-controlled native oxidation of silicon for up to 5 h or more. It could be a suitable and more robust surface cleaning and passivation process for the industry, but heavy water is expensive. As a cheaper procedure, we showed that 1 min vapor phase treatment at 65 °C of heavy water (D₂O) + 50% HF (e.g. 20:1) mixture was enough to remove the native oxide and to passivate the Si surface without any degradation of the atomic surface flatness. The surface evolution of the D-passivated surface was followed by contact angle measurements, spectroscopic ellipsometry (SE), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), infrared absorption spectroscopy (IR), surface potential and surface photovoltage (SPV) mapping and light induced potential transient method. Qualification and the results were compared to the H-passivated, bare and native oxide covered Si surface. Our passivation test results confirmed that using D-passivation on Si surface is a promising method in the MOS technology and the interface engineering processes.     

准分子激光线宽压缩方法的研究

介绍了准分子激光线宽压缩的各种方法及其各自特点,并用单个标准具对308nmXeCI准分子激光进行了线宽压缩实验。     

Riesz Basis Generation of Abstract Second-Order Partial Differential Equation Systems with General Non-Separated Boundary Conditions

Riesz basis analysis for a class of general second-order partial differential equation systems with nonseparated boundary conditions is conducted. Using the modern spectral analysis approach for parameterized ordinary differential operators, it is shown that the Riesz basis property holds for the general system if its associated characteristic equation is strongly regular. The Riesz basis property can then be readily established in a unified manner for many one-dimensional second-order systems such as linear string and beam equations with collocated or noncollocated boundary feedbacks and tip mass attached systems. Three demonstrative examples are presented.     

A parabolic variant of H-measures

H-measures, as originally introduced by Luc Tartar and Patrick Gérard, are suited to hyperbolic problems. However, they turned out not to be well adjusted to the study of parabolic equations. A variant of H-measures is proposed, which is much better adapted to such kind of problems. We present the new parabolic scaling and the main ingredients for the proof of existence of the new variant. Some applications to the Schrödinger equation and vibrating plate equation are shown, together with an outlook to possible applications in other problems.     

Absence of Critical Mass Densities for a Vibrating Membrane

We study the dependence of the eigenvalues of a N-dimensional vibrating membrane upon variation of the mass density. We prove that the elementary symmetric functions of the eigenvalues depend real-analytically on the mass density and that such functions have no critical points with constant mass constraint. In particular, the elementary symmetric functions of the eigenvalues, hence all simple eigenvalues, have no local maxima or minima on the set of those mass densities with a prescribed total mass.     

The Asymptotics of the Two-Dimensional Wave Equation for a General Multi-Connected Vibrating Membrane with Piecewise Smooth Robin Boundary Conditions

The asymptotic expansion for small |t| of the trace of the wave kernel ∧↑μ(t) =∑v=1^∞exp(-it μv^1/2), where i= √-1 and {μv}v=1^∞ are the eigenvalues of the negative Laplacian -△=-∑β=1^2(δ/δx^β)^2 in the (x^1, x^2)-plane, is studied for a multi-connected vibrating membrane Ω in R^2 surrounded by simply connected bounded domains Ωj with smooth boundaries δΩj(j=1,...,n), where a finite number of piecewise smooth Robin boundary conditions on the piecewise smooth components Гi(i=1 κj-1,...,κj) of the boundaries δΩj are considered, such that δΩj=∪i=1 κj-1^κj Гi and κ0=0. The basic problem is to extract information on the geometry of Ω using the wave equation approach. Some geometric quantities of Ω (e.g. the area of Ω, the total lengths of its boundary, the curvature of its boundary, the number of the holes of Ω, etc.) are determined from the asymptotic expansion of the trace of the wave kernel ∧↑μ(t) for small |t|.     

Predict acoustic field of vibrating beams by Helmholtz integral equation and BEM

New method of predicting the acoustic field radiation of vibratingbodies is presented.It is based on the Helmholtz integral equation and bounda-ry element method and applicable to the use of computers.The acoustic field ofthe cantilever beams has been calculated and measured.Test results haveproved the effectiveness of the predicting method.     

磁强计的计算机接口电路故障分析

本文介绍了震动样品磁强计 (VSM)计算机接口电路的故障分析及故障排除     

Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene – a single atomic layer of graphite – is the newest member in the family of carbon allotropes and has emerged as the “celeb” material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.     

Magnetically separable template assisted iron nanoparticle for the enhancement of latent fingerprints

The article focuses on the cost-effective and high-quality non-destructive template-assisted magnetic mesoporous iron nanomaterial for latent Fingerprint examination (LFPs). The iron nanomaterial is synthesized using the CTAB template by the co-precipitation method. The synthesized nanomaterial is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ sorption- Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), EDX elemental mapping, Vibrating sample magnetometer (VSM), UV–Visible spectroscopy, and XPS. The N2 sorption showed that the synthesized material is mesoporous with an H1 hysteresis loop. The TEM images showed the spherical shape and particle size to be around 55–65 nm. The VSM analysis successfully established its ferromagnetic nature. The synthesized nanomaterial showed excellent magnetic recovery after its utilization and retained fingerprints for 2–3 months with the same resolution. We collected the fingerprint on both non-porous and non-porous surfaces with better-developed ridges of fingerprints compared to conventional fingerprinting dyes (charcoal).