Y. Xu

Comparison of the x-ray spectroscopy response and charge transport properties of semi-insulating In/Al doped CdZnTe crystals

The x-ray spectroscopy performance of In/Al doped CdZnTe planar detectors based on as-grown crystals were investigated at room temperature, using a Tb x-ray source with a principle energy of 44.2 keV. The observed broadening in the photopeak resolution was attributed to incomplete charge carrier collection due to carrier trapping and scattering by the defects in the crystal. Alpha particle spectroscopy and pulse shape rise time analysis were used to measure the electron mobility lifetime product (μτ), as well as the mobility (μ) of the CdZnTe material grown with different dopant concentrations. To further clarify the role of the dopant and associated trapping states, temperature dependent alpha particle spectroscopy and pulse shapes were investigated at various applied bias fields over a temperature range from 200 to 300 K. CdZnTe doped with 1.5 ppm In exhibits excellent x-ray spectral resolution and charge transport properties, which implies a lower density of trapping centers in the crystal. The deep le...

Tuning flexural elastic wave propagation in electroactive phononic crystals

In this paper, we investigate the flexural elastic wave propagation properties in phononic crystals (PCs) consisting of co-axial steel and electrorheological (ER) elastomer pillars deposited on a thin plate. The finite element method and the super cell technique are used to calculate the band structures and transmission spectra. It is found that the band gap boundaries of the PCs can be tuned by applying an electric field to the ER elastomer component. The relationship between the band gap boundaries and the electric field is given. It is also found that point and line defects can be created by properly applying an electric field to some of the cells. These defects bring defect bands inside the original band gaps and lead to elastic wave confinement in the point defect or along the line defect. The dependence of the defect band frequencies on the electric field is expounded. Band gap tunability, wave confinement, and wave guiding achieved by applying electric field in this paper are useful in applications of flexural vibration reduction and energy harvesting in engineering.In this paper, we investigate the flexural elastic wave propagation properties in phononic crystals (PCs) consisting of co-axial steel and electrorheological (ER) elastomer pillars deposited on a thin plate. The finite element method and the super cell technique are used to calculate the band structures and transmission spectra. It is found that the band gap boundaries of the PCs can be tuned by applying an electric field to the ER elastomer component. The relationship between the band gap boundaries and the electric field is given. It is also found that point and line defects can be created by properly applying an electric field to some of the cells. These defects bring defect bands inside the original band gaps and lead to elastic wave confinement in the point defect or along the line defect. The dependence of the defect band frequencies on the electric field is expounded. Band gap tunability, wave confinement, and wave guiding achieved by applying electric field in this paper are useful in applications...