No abstract

In this paper, we describe the improvement of secondary ion mass spectrometry (SIMS) profile analysis by a new approach based on partial deconvolution combined with scale-frequency shrinkage. The SIMS profiles are obtained by analysis of the delta layers of boron doped silicon in a silicon matrix, analyzed using Cameca-Ims6f at oblique incidence. These profiles can be approximated closely by exponential-like tail distributions with decay length, which characterizes the collisional mixing effect. The partial deconvolution removes the residual ion mixing effect. The contributions of high-frequency noise are removed by shrinkage to a great extent of the profiles. It is shown that this approach leads to a marked improvement in depth resolution without producing artifacts and aberrations caused principally by noise. Furthermore, it is shown that the asymmetry of the delta layers, caused by the collisional mixing effect, is completely removed, the decay length is decreased by a factor of 4 compared with that before deconvolution.

Multiresolution deconvolution (MD), based on Tikhonov–Miller regularization and wavelet transformation, was developed and applied to improve the depth resolution of secondary ion mass spectrometry (SIMS) profiles. Both local application of the regularization parameter and shrinking the wavelet coefficients of blurred and estimated solutions at each resolution level in MD provide to smoothed results without the risk of generating artifacts related to noise content in the profile. This led to a significant improvement in the depth resolution. The SIMS profiles were obtained by analysis of delta layers of boron in a silicon matrix using a Cameca-Ims6f instrument. The results obtained by using the MD algorithm are compared to those obtained by monoresolution deconvolution which is Tikhonov–Miller regularization with a model of solution (TMMS). Finally, the advantages and limitations of the MD algorithm are presented and discussed.

Because of its photoelectrochemical properties, titanium dioxide is an attractive material in photoelectrolysis of water for hydrogen production. Magnetron sputtering is a common and practicable technique that has been used to deposit TiO 2 thin films with homogeneous uniformity and reproducibility for various applications. This work deals with the growth of anatse titanium dioxide on indium tin oxide substrate using reactive sputtering DC magnetron method to use them in hydrogen production. In view of the influence of processing techniques on the TiO 2 photoelectrochemical properties, the choice of the appropriate technique and the optimization of deposition parameters and thermal traitments must be suitable for efficient water splitting reactions into hydrogen and oxygen. Under the conditions of deposition, anatase TiO 2 thin films were prepared and the effect of annealing temperature on their structural and optical properties was examined. The X-ray analyzes and Raman spectroscopy show that the TiO 2 films with a thickness of 500 nm obtained after annealing at 350 and 450 °C for 60 min of time deposition in an ambient air are anatase phase. The crystallite size of the films is increased with increasing annealing temperature. The deposited TiO 2 thin films have high transparency in the visible range and opaque in the UV region. The optical properties of the films are found to be closely related to the microstructure and crystallographic structure, which depend on the annealing temperature.

Complex modes, singular value decomposition, shielded microstrip, fin line. Complex waves in shielded lossless inhomogeneous waveguiding structures are investigated. A new theoretical approach for wave interaction, which may result in complex modes, is developed using the theory of coupled modes. It is shown that complex modes may exist in perturbed homogeneous waveguiding structures as a result of the coupling of a pair of degenerate or nearly degenerate modes. Coupled modes, in microstrips and fin lines, are discussed and numerical data are compared. © 1994 John Wiley & Sons, Inc.