Hybrid Density Functional Study of the Local Structures and Energy Levels of CaAlO:Ce.

First-principles calculations were carried out for the electronic structures of Ce in calcium aluminate phosphors, CaAlO, and their effects on luminescence properties. Hybrid density functional approaches were used to overcome the well-known underestimation of band gaps of conventional density functional approaches and to calculate the energy levels of Ce ions more accurately. The obtained 4f-5d excitation and emission energies show good consistency with measured values.

Coherence times of precise depth controlled NV centers in diamond.

We investigated the depth dependence of coherence times of nitrogen-vacancy (NV) centers through precise depth control using oxidative etching at 580 °C in air. By successive nanoscale etching, NV centers could be brought close to the diamond surface step by step, which enabled us to track the evolution of the number of NV centers remaining in the chip and to study the depth dependence of coherence times of NV centers with diamond etching. Our results showed that the coherence times of NV centers declined rapidly with the depth reduction in the last about 22 nm before they finally disappeared, which revealed a critical depth for the influence of a rapid fluctuating surface spin bath.

Memory characteristics of metal-oxide-semiconductor structures based on Ge nanoclusters-embedded GeO(x) films grown at low temperature.

The memory devices constructed from the Ge-nanoclusters embedded GeO(x) layer deposited by the laser-assisted chemical vapor deposition (LACVD) system were fabricated. The Ge nanoclusters were observed by a high-resolution transmission electron microscopy. Using the capacitance versus voltage (C-V) and the conductance versus voltage (G-V) characteristics measured under various frequencies, the memory effect observed in the C-V curves was dominantly attributed to the charge storage in the Ge nanoclusters.

Charge storage characteristics of silicon nanoclusters in silicon nitride matrix grown by laser assisted chemical vapor deposition method.

The capacitance-voltage (C-V) and charge retention characteristics of the metal-insulator-semiconductor (MIS) structure, in which the insulator layer was composed of silicon nanocluster-embedded silicon nitride, were studied. The memory effect of this MIS structure was dominantly attributed to the charge storage in the silicon nanoclusters. The relation between the flatband voltage shift and the amount of charges stored in the nanocluster-embedded insulator layer was discussed.

Optical properties of nanocrystalline Y2O3:Eu depending on its odd structure.

The structure of nanocrystalline Y2O3:Eu prepared by a combustion reaction was analyzed by XRD and high-resolution electron microscopy. Compared with a large-scale particles, 5-nm Y2O3:Eu particles presented as distorted crystallite and rough surfaces. Luminescent and absorption properties of nano-Y2O3:Eu showed remarkably particle size effects.

Improved procedure on the microscopic approach to determine colloidal stability.

We present an improved procedure on the approach to determine the stability of polystyrene spheres at microscopic particle levels by means of artificially induced particle collisions with the aid of optical tweezers [J. Chem. Phys.

Axial optical trapping forces on two particles trapped simultaneously by optical tweezers.

Optical tweezers, which utilize radiation pressure to control and manipulate microscopic particles, are used for a large number of applications in biology and colloid science. In most applications a single optical tweezers is used to control one single particle. However, two or more particles can be trapped simultaneously.

Preparation of single rice chromosome for construction of a DNA library using a laser microbeam trap.

We report the development of a laser micromanipulation system and its application in the isolation of individual rice chromosomes directly from a metaphase cell. Microdissection and flow sorting are two major methods for the isolation of single chromosome. These methods are dependent on the techniques of chromosome spread and chromosome suspension, respectively.