Trinh Vo

Diffusion in two-dimensional colloid-DNA systems

Diffusion in quasi-two-dimensional colloid-DNA systems are studied by enhanced video microscopy and image analysis. The colloidal particles are polystyrene spheres and DNA is linear or circular bacteriophage λ-DNA. Dyed linear DNA molecules in pure linear DNA solutions are tracked by fluorescence microscopy. The diffusivities of the colloidal particles and of the DNA molecules are found to decrease sharply at low DNA concentration; the diffusivities of the colloidal particles in both linear and circular DNA exhibit a change in slope as the DNA concentration increases.

Phase transitions of magnetic nanoclusters in metals and semiconductors

The interactions and phase transitions of magnetic nanoclusters embedded in nonmagnetic metals and semiconductors are investigated theoretically. As a consequence of the temperature dependence of the indirect interactions, it is shown that for semiconductors several ferromagnetic phase transitions are possible depending on the size of the nanoclusters, whereas for metals a single ferromagnetic phase transition occurs independently of the size of the nanoclusters. The spontaneous magnetization is evaluated in all cases.

Short-range order in linear systems

For linear systems in the continuum in which the particles interact with nearest-neighbor forces, the pair distribution function at short distances can be expressed exactly in a simple form. Results are given for various hard-core interaction potentials, in which the attractive potential is either constant (square-well potential), linear, or V-shaped. The second form is related to the depletion interaction.

Processing and characterization of LiNbO3 thin film for metal Ferroelectric Semiconductor field effect transistor (MFSFET) application

Abstract LiNbO3 thin films were deposited on P-Si(111) substrates. C-axis (006) oriented films were fabricated with RF magnetron sputtering and (012) oriented films were achieved by metal organic decomposition (MOD). High frequency C-V measurement showed a clockwise rotation hysteresis curve, which corresponded to the ferroelectric switching. A polarization vs. voltage hysteresis curve of a Metal-Ferroelectric-Semiconductor (MFS) capacitor was measured with a modified Sawyer-Tower circuit. Remnant polarization as high as 65μC/cm2 was found from sputtering deposited sample.