Juh Tzeng Lue

A review of characterization and physical property studies of metallic nanoparticles

In this survey, the characterization of metallic nanoparticles prepared by various methods and the physical properties including the theory and measurements of linear and nonlinear optics, electric and magnetic properties are reviewed. Technical results involving linear optical absorption, optical second harmonic generation, temperature dependence of resistivity, electron paramagnetic resonance and magnetic susceptibility measurements were portrayed. A number of fascinating and provocative results have been developed that lead our perspective understanding of quantum size confinements.

Magnetoreception System in Honeybees (Apis mellifera)

Honeybees (Apis mellifera) undergo iron biomineralization, providing the basis for magnetoreception. We showed earlier the presence of superparamagnetic magnetite in iron granules formed in honeybees, and subscribed to the notion that external magnetic fields may cause expansion or contraction of the superparamagnetic particles in an orientation-specific manner, relaying the signal via cytoskeleton (Hsu and Li 1994). In this study, we established a size-density purification procedure, with which quantitative amount of iron granules was obtained from honey bee trophocytes and characterized; the density of iron granules was determined to be 1.25 g/cm3. While we confirmed the presence of superparamagnetic magnetite in the iron granules, we observed changes in the size of the magnetic granules in the trophycytes upon applying additional magnetic field to the cells. A concomitant release of calcium ion was observed by confocal microscope. This size fluctuation triggered the increase of intracellular Ca+2 , which was inhibited by colchicines and latrunculin B, known to be blockers for microtubule and microfilament syntheses, respectively. The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response. A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.

Arc annealing of BF+2 implanted silicon by a short pulse flash lamp

Step‐junction diodes are obtained from BF+2 implanted silicon irradiated by a single pulse of light from a flash lamp. The FWHM is 100 μs with energy densities ranging from 12.4 to 20.6 J/cm2. The sheet resistance and the I‐V characteristic have been used to confirm the annealing process.

The barrier height change and current transport phenomena with the presence of interfacial layer in MIS Schottky barrier solar cells

Abstract In this comprehensive study, several interesting results which are different from those previous are reported. We find the barrier height decreases for n -type and increases for p -type when positive ions are introduced into the insulating layer. The increase of open circuit voltage can be traced to the suppression of the dark saturation current by the depletion field induced by the positive charge, and to the diminution of the majority tunneling current by the oxide potential barrier. The tunneling probabilities for majority and minority carriers are different; there are only a finite amount of majority carriers with thermionic energy greater than q ( V bi − V s ) which can surmount the depletion potential and tunnel into the metal, whereas the photogenerated minority carriers derive kinetic energy in the depletion layer making tunneling easier. Transport coefficients for electrons to transmit from metal to semiconductor and from semiconductor to metal are different for the departure of built in potentials during illumination.

The change from paramagnetic resonance to ferromagnetic resonance for iron nanoparticles made by the sol–gel method

Abstract Sol–gel glass embedded with iron nanoparticles provides fascinating features inheriting paramagnetic, ferromagnetic, and superparamagnetic resonance properties under various compositional weight ratios and annealing conditions. Two spectra arising from paramagnetic Fe 3+ ions and ferrimagnetic Fe 2 O 3 particles both centered at g e =2.0 compete with intensities as the annealing temperature T A increases. Meanwhile, the resonance line width of Fe 2 O 3 particles sharply decreases due to the strong exchange narrowing. The asymmetric line shape and the rather broad line width can be elucidated by the ferromagnetic resonance of the single domain Fe 2 O 3 nanoparticles.

Grain boundary scattering in the normal state resistivity of superconducting NbN thin films

NbN films prepared by reactive dc sputtering at high ambient pressure exhibit anomalous normal‐state resistivity, as pervasively reported in literature. Most of the prepared films exhibit negative temperature coefficient of resistivity (TCR), while a few films are metallic (TCR≳0) near room temperature and are nonmetallic (TCR<0) at temperatures between 200 and 300 K. Theoretical fittings by the model of grain‐boundary scattering yield a better congruence with the experimental data, than those by exploiting the model of electron localization. This suggests that the transport mechanism of sputtered film prevails manipulated by grain boundary scattering rather than by defect scattering or by impurity scattering.

Optical second harmonic generation from thin silver films

Abstract In this work, silver films of various thicknesses from 1 to 180 nm are vacuum evaporated on microscopic glass plates. The external reflection (ER) measurement of the second-harmonic generation (SHG) indicates that the peak intensity decreases dramatically as the film thickness is reduced below 20 nm and the incident angle yielding maximum SHG shifts toward lower values. The theoretical calculation based on the hydrodynamical model with excitation and interference of multiple reflections on both surfaces of the metal film can successfully address the salient features of these observations. Enhancement of the SHG light occurs only for film thickness as small as 15 nm, where the granular structure is obvious as observed from an atomic force microscope.

A new method developed in measuring the dielectric constants of metallic nanoparticles by a microwave double-cavity dielectric resonator

A microwave double dielectric resonator is implemented to measure the dielectric constants of nano-metallic powders. The metallic nanoparticles prepared by vacuum evaporation in inert gas are collected and mixed with alumina powder to fill the inner hole of a sapphire disc by which the resonant frequency and Q factor are measured at the TE/sub 011/ mode to derive the complex dielectric constant.

Some remarks on annealing and doping in CuInS2

This paper addresses problems associated with thermal annealing and n‐type and p‐type doping in CuInS2. The results of incorporating impurities like Zn and P in CuInS2 single crystals by different methods are reported. Some evidence has been provided to explain the formation of precipitates being the limiting factor to exhibit the shallow acceptor property. The electron beam annealing of phosphorus‐implanted CuInS2 has been shown for the first time to be an effective way for p‐type conductivity control by extrinsic impurities in any I‐III‐VI2 ternary chalcopyrite.

Ellipsometry measurements of nickel silicides

The real (n) and imaginary (k) parts of the refraction index of Ni2Si, NiSi, and NiSi2 silicides are measured by an ellipsometer in the optical range of 4000–7000 A. The n and k are within the values of 2.0–3.5 for the high‐temperature annealed nickel silicides.