Epitaxial Growth of High-Quality Silicon Films on Double-Layer Porous Silicon

The epitaxial growth of a high-quality silicon layer on double-layer porous silicon by ultra-high vacuum/chemical vapour deposition has been reported. The two-step anodization process results in a double-layer porous silicon structure with a different porosity. This double-layer porous silicon structure and an extended low-temperature annealing in a vacuum system was found to be helpful in subsequent silicon epitaxial growth. X-ray diffraction,cross-sectional transmission electron microscopy and spreading resistance testing were used in this work to study the properties of epitaxial silicon layers grown on the double-layer porous silicon. The results show that the epitaxial silicon layer is of good crystallinity and the same orientation with the silicon substrate and the porous silicon layer.

Structural and Optical Characterizations of ZnO Films Grown by Reactive Electron Beam Evaporation

Low temperature epitaxial growth of ZnO films is achieved on Si(001)substrates by reactive electron beam evap oration.Growth temperature is varied from 125 C to 420 C and the optimum temperature is found between 200°C and 300 C.X-ray diffraction shows that the ZnO films are highly c-axis oriented and the line width of(002)diffraction peak is significantly smaller than that measured from the ZnO films deposited by magnetron sput tering.The combined photoluminescence and photoluminescence excitation(PLE)spectroscopic measurements demonstrate the sharp band-absorption edge and exciton absorption in the ZnO films.PLE has also revealed that the absorption characteristic near the band edge is remarkably improved with the increase of oxygen content in the ZnO films,although x-ray diffraction analysis shows that the crystalline structure of ZnO films grown under different oxygen pressures remains unchanged.

Simulation of scattering in dense medium by Monte Carlo method

We present a Monte Carlo (MC) method to simulate the scattering for medium within randomly distributed particles, discuss the convergence of this method by varying the size parameter ka, volume parameter η and calculation parameter Ni, then compare this method with the classical iteration method with the same parameters. The calculation results showed that this method has good convergence and accords with the iteration method while consuming less CPU time. At the end of this paper, this method is used to discuss the visual light scatter in the c-Si/α-Si films.

Surface analysis, hydrogen adsorption and electrochemical performance of alkali-reduce treated hydrogen storage alloy

The hydrogen storage alloy powders (MlNi 4.0 Co 0.6 Al 0.4 , Ml=rich La mischmetal) were treated in a hot 6?mol/L KOH+ 0.02?mol/L KBH 4 solution, the surface compositions and chemical states of the treated and untreated alloys were analyzed by XPS and EDX, the hydrogen adsorption on the surface of these alloys was evaluated by thermal desorption spectroscopy (TDS), the effects of the surface treatment on the electrochemical performances of the alloy electrodes were investigated. The results show that the hydrogen adsorption is greatly strengthened by the surface modification, and hence leads to marked improvement in the electrocatalytic activity, the treated alloy exhibits higher exchange current density and lower apparent activation energy for the hydrogen electrode reaction than the untreated alloy.