Papers by Keyword: Interference Microscopy

Abstract: Guest diffusion in nanoporous materials reveals a wide spectrum of phenomena associated with random mass transfer in condensed matter quite in general. Taking advantage of their potentials for monitoring mass transfer over microscopic dimensions, micro-imaging (by interference microscopy and IR spectroscopy) and pulsed field gradient (PFG) NMR are exploited for providing typical examples highlighting these options. Starting with the surprise provided by the application of these microscopic measuring techniques to nanoporous materials, namely discrepancies of up to five orders of magnitude in comparison with the so far well-established data, the review covers some of the most impressive further results, including the determination of sticking coefficients on the surfaces of these materials and the specification and detection of conditions where molecular mass transfer is accelerated rather than hampered by counter fluxes.

Abstract: The application of interference microscopy (IFM) and infrared microscopy (IRM) to monitor the evolution of the concentration of guest molecules in nanoporous host materials opens a new field of diffusion research in condensed matter. It combines the methodical virtues of the profiling methods of solid-state diffusion studies with the benefit of the mobility enhancement in fluids. We are going to illustrate the rich options of diffusion studies provided by this novel experimental approach.

Abstract: We report a damage-free and efficient planarization process for silicon carbide (SiC) using platinum as a catalyst in hydrofluoric acid (HF) solution. In previous studies, 4H-SiC (0001) on-axis wafers were planarized by this process and an extremely flat surface was obtained. However, electronic device substrates require off-axis wafers. In the present study, 4H-SiC (0001) 8° off-axis Si-face wafers were planarized using a Pt catalyst plate and HF solution. In the first trial using these wafers, the surface roughness worsened and a diagonal pattern was observed by phase-shift interference microscopy. The pattern seemed to have been formed when the Pt plate morphology was transcribed onto the wafer. The removal rate of the 8° off-axis Si-face wafer is much greater than that of the on-axis Si-face wafer. Thus, we concluded that the use of a smoother catalyst plate would be necessary to obtain a smooth 8° off-axis Si-face wafer surface. Improving the Pt plate morphology by hand lapping also improved the surface roughness of the processed wafer as compared with the preprocessed surface. The maximum height of the surface irregularity (peak-to-valley, P-V) and root-mean-square roughness were improved to 0.513 nm and 0.044 nm, respectively, as determined by atomic force microscopy (2×2 μm2).