Mingshaw Wu

Aluminum nanowire polarizing grids: Fabrication and analysis

We have produced metal wire grids with 33nm periodicity, using a thin film of a self-assembling diblock copolymer as a template. These grids, supported on fused quartz wafers, function as transmission polarizers for visible and near-ultraviolet lights. Their polarization efficiency is measured to be near 50% in the visible. Quantitative comparison with a new theoretical analysis of such wire grids indicates that they should perform well into the far UV. This analysis also explains the reversal in polarization direction at shorter wavelengths which we observe in our specimens.

Laterally Modulated 2D Electron System in the Extreme Quantum Limit

We report on magnetotransport of a two-dimensional electron system (2DES), located 32 nm below the surface, with a surface superlattice gate structure of periodicity 39 nm imposing a periodic modulation of its potential. For low Landau level fillings nu, the diagonal resistivity displays a rich pattern of fluctuations, even though the disorder dominates over the periodic modulation. Theoretical arguments based on the combined effects of the long-wavelength, strong disorder and the short-wavelength, weak periodic modulation present in the 2DES qualitatively explain the data.

Aluminum nanowire polarizing grids: fabrication and analysis

We have produced aluminum wire grids with 33 nm periodicity using a thin film of a self-assembling cylinder forming diblock copolymer as a template. These grids, supported on fused quartz wafers, function as transmission polarizers for visible and near-ultraviolet lights and are a thin design, compared to commercially available polarization prisms. Their polarization efficiency is measured to be near 50% in the visible. Quantitative comparison with a new theoretical analysis of such wire grids indicates that they should perform well into the far UV. This analysis also explains a reversal in polarization direction at short wavelengths which we observe in our specimens. This is an expanded version of a previous paper.1

Nano-arrays of optically addressable rare-earth-doped semiconductor quantum dots for quantum computing

Results have been presented on isolating rare earth atoms in small numbers in semiconductor nanoparticles so as to use their organized arrays as hardware for quantum computing. We have tailored atomic states of rare earths, fabricated nanoparticles where these atomic systems are incorporated in small numbers and have patterned arrays of nano-holes on semi-conducting and polymer surfaces to encapsulate these rare earth doped nanoparticles. Results are presented on fabrication, microscopy and spectroscopy of these structures.