Free radial oscillation of a sphere in relativistic elasticity theory

The spherically symmetric free radial oscillation in the first post-Newtonian approximation for a homogeneous and isotropic elastic sphere with a constant density is studied. Based on the Xu, Wu, and Soffel formalism, the relation of the oscillation frequency of the sphere with the radius, mass density, and elastic constants of the sphere is derived by using the successive approximation method.

OXYGEN ANALYSES IN HIGH-TC SUPERCONDUCTING FILMS BY MEV PROTON ELASTIC BACKSCATTERING

A technique for analysis of total oxygen contents in high-T(c) superconducting films is demonstrated. It uses elastic backscattering (EBS) of 1.5-2.5 MeV protons. By comparing the H EBS spectra from substrate materials, the absolute oxygen content in the films can be easily calculated. It is estimated that the analysis can be accurate to better than 5% for YBCO films with thicknesses from several hundred angstroms to several microns. Comparisons with RBS are given and advantages of this technique are shown.

A NEW METHOD FOR MEASURING THE EFFECTIVE DIFFUSION CONSTANT OF 2-DIMENSIONAL ELECTRONS IN THE PRESENCE OF MAGNETIC-FIELDS

The transient charge response Q(t) of a two-dimensional electron gas (2DEG) in GaAs/AlxGa1-xAs heterostructures to a small pulse of the gate voltage, applied between the top gate and source electrodes in a Corbino structure, was employed to directly measure the effective diffusion constant of a 2DEG in the quantum Hall regime. The measured diffusion constant D showed a drastic change as the magnetic field was swept through the integer fillings of the Landau levels.

MEV PROTON ELASTIC BACKSCATTERING ANALYSIS OF SILICON-NITRIDE AND OXIDE LAYERS ON SILICON

A simple method for the analysis of concentration ratios N/Si and O/Si in silicon nitride and oxide layers on silicon substrate is presented. 1.95-MeV proton elastic backscattering was used to determine the composition and density. A comparison with 2.1-MeV helium Rutherford backscattering measurements is given. Results are in good agreement with each other. The method is especially useful to analyze samples of 20 000 angstrom or thicker layers. We conclude that these two techniques are complementary for the measurements of samples with different thickness. A brief discussion has been given on results.

SHEAR-DEFORMATION-POTENTIAL CONSTANT OF THE CONDUCTION-BAND MINIMA OF SI - EXPERIMENTAL-DETERMINATION BY THE DEEP-LEVEL CAPACITANCE TRANSIENT METHOD

The shear-deformation-potential constant XI-u of the conduction-band minima of Si has been measured by a method which we called deep-level capacitance transient under uniaxial stress. The uniaxial-stress (F) dependence of the electron emission rate e(n) from deep levels to the split conduction-band minima of Si has been analyzed. Theoretical curves are in good agreement with experimental data for the S0 and S+ deep levels in Si. The values of XI-u obtained by the method are 11.1 +/- 0.3 eV at 148.9 K and 11.3 +/- 0.3 eV at 223.6 K. The analysis and the XI-u values obtained are also valuable for symmetry determination of deep electron traps in Si.

Assessment of the structural properties of GaAs/Si epilayers using X-ray (004) and (220) reflections

We improved the method previously used to determine the lattice constants and misorientation of GaAs/Si by recording the patterns of X-ray (004) and (220) reflections. The (220) reflection was measured from the (110) cross section of a GaAs/Si epilayer. The structural properties of the GaAs/Si epilayers grown by metal-organic chemical-vapor deposition (MOCVD) using an ultrathin a-Si buffer layer were investigated. The rotation angle of GaAs/Si epilayers grown by MOCVD using an a-Si buffer layer is very small and the lattice constants of these GaAs/Si epilayers agree quite well with elastic theory.

Elastic Strain Field Distribution of a Self-Organized Growth Lensed-Shaped Quantum Dot by Finite Element Method

The stress and strain fields in self-organized growth coherent quantum dots (QD) structures are investigated in detail by two-dimension and three-dimension finite element analyses for lensed-shaped QDs. The nonobjective isolate quantum dot system is used. The calculated results can be directly used to evaluate the conductive band and valence band confinement potential and strain introduced by the effective mass of the charge carriers in strain QD.

Investigation on Elastic Strain Energy in Quantum Dots

In this paper, we calculated the elastic strain and elastic strain energy inside the semiconductor quantum dots by using the finite element programming package ANSYS 6.0. The values of elastic strain and strain energy in the three shapes of quantum dots were calculated, and led to the conclusion that the pyramid island structure of quantum dots is the most stable shape in the three shapes under thermal-equilibrium condition.

Modulation of Photonic Bandgap and Localized States by Dielectric Constant Contrast and Filling Factor in Photonic Crystals

The band structure of 2D photonic crystals (PCs) and localized states resulting from defects are analyzed by finite-difference time-domain (FDTD) technique and Pade approximation. The effect of dielectric constant contrast and filling factor on photonic bandgap (PBG) for perfect PCs and localized states in PCs with point defects are investigated. The resonant frequencies and quality factors are calculated for PCs with different defects. The numerical results show that it is possible to modulate the location, width and number of PBGs and frequencies of the localized states only by changing the dielectric constant contrast and filling factor.

Nonlinear elastic waves in a monatomic chain with nonlinear interaction

Nonlinear wave equation for a one-dimensional anharmonic crystal lattice in terms of its microscopic parameters is obtained by means of a continuum approximation. Using a small time scale transformation, the nonlinear wave equation is reduced to a combined KdV equation and its single soliton solution yields the supersonic kink form of nonlinear elastic waves for the system.