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GaN caps are commonly used to reduce sheet charge modulation induced by AlGaN/GaN surface potential. However, the details on how GaN caps affect C – V and G – V characteristics are still unclear. In this paper, we report a difference between these characteristics with and without GaN caps, and we discovered a mechanism in which GaN caps act as quantum wells to affect the charging and discharging of interface states. Finally, we developed a numerical model to simulate admittance characteristics of AlGaN/GaN MIS structures with a GaN cap in high accuracy. [ABSTRACT FROM AUTHOR]

We propose a tunable acoustic filter using superlattices constructed by random stacking of solid and fluid layers. Acoustic waves are localized in the random superlattices (RSLs) and the transmission rates substantially decay to 0 except for the resonance transmissions where the acoustic waves are delocalized. The transmission rates become unity for the resonance transmissions. The resonance frequencies depend on the layer thicknesses, and we can modulate the transmission spectra from transparent to opaque, and vice versa, modifying the layer thicknesses. We numerically illustrate the changes in the transport properties for the aluminum/water RSLs, and suggest to exploit the RSLs for the tunable acoustic filters. [ABSTRACT FROM AUTHOR]

We propose a rectifier of elastic waves in a thin plate, which is made of an elastically isotropic material containing a periodic array of triangular holes as scatterers, and demonstrate numerically that it works both for the symmetric and anti-symmetric Lamb waves as well as shear horizontal waves. The rectification is caused by the geometric effects on wave scattering due to the asymmetric scatterers, while the interplay between the mode conversion and interference effects among the scattered waves owing to the periodic arrangement of scatterers complicates it. The mechanism makes it possible to rectify the typical elastic waves in the system above the threshold frequency corresponding to the wavelength equivalent to the periodicity of scatterers. [ABSTRACT FROM AUTHOR]

Investigates the influence of the tip dimensions on a vibrating cantilever in atomic force microscopy. Effect of finite tip size changes on the boundary conditions for the flexural motion; Rigidity of the cantilever-tip-sample combination; Implications for the quantitative analysis of atomic force microscopy.

Presents an erratum of the article 'Vibrational Dynamics of Force Microscopy: Effect of Tip Dimensions' published in the 1997 issue of the journal Applied Physics Letters, Volume 71.

Random telegraph noise in the electric current produced by shot noise is predicted for an array of movable colloid particles by Monte Carlo and molecular dynamics calculations. The electron transport is attributed to the shuttle mechanism where moving colloid particles carry charges. The colloid-particle motion induced by the source-drain voltage shows periodic and/or quasiperiodic vibrations, and the current value depends on the vibration modes. Shot noise that is uncorrelated with the colloid-particle motion causes transitions between the periodic and quasiperiodic vibration modes, resulting in random switching between the current levels corresponding to the vibration modes.