A study of apatite crystals from the Asio mine, Japan, showed sectoral texture related to the growth of the crystal, and with optically biaxial properties within the sectors. Wet chemical analysis gave a composition Ca5(PO4)3(F0.64,OH0.38,Cl0.01)1.03 for the specimen.

Additional diffraction spots were not observed in precession and oscillation X-ray photographs and electron diffraction photographs. Since the internal textures correlate with the surface growth features, it is suggested that the internal textures and the unusual optical properties were produced during nonequilibrium crystal growth. The fluorine/hydroxyl sites in hexagonal apatite are symmetrically equivalent in the solid crystal but, at a growth surface, this equivalence may be lost, resulting in a reduction of crystal symmetry. Heating of the apatite to about 850°C results in the almost complete disappearance of the optical anomalies due to disordering, which may be related to the loss of hydroxyl from the crystal.

A new continuous sediment core (PY608W-PC; 3.8 m length) for reconstruction of climatic and environmental changes in the southeastern Tibetan Plateau was taken from the eastern part of Lake Pumoyum Co in August 2006. Sediment layers of the lower part of PY608W-PC (380–300 cm depth) were composed mainly of relatively large plant residues (up to ∼3 cm in length) with an admixture of fine sand and sandy silt. The large plant residues disappeared at ∼300–290 cm depth in core PY608W-PC and were replaced by silt-silty clay. The large plant residues from the lower part of PY608W-PC could be aquatic, because the plant residues were extremely enriched in 13C (up to –3.0‰, −5.6 ± 2.3‰ on average). On the other hand, the plant residue concentrates (PRC fractions) from the upper part of the core (290–0 cm in depth) could be terrestrial C3 plants (δ13C = –21.8 ± 1.7‰ on average). Radiocarbon dating was performed on the large plant residues and PRC fractions from the PY608W-PC sediment core, which represented the chronology from ∼19,000 cal BP to present.

We report a photoreflectance (PR) characterization of InP/GaAsSb double-heterojunction bipolar transistor (DHBT) epitaxial wafers grown by metal-organic vapor-phase epitaxy (MOVPE). The origin of the Franz-Keldysh oscillations (FKOs) in the PR spectra was identified by step etching of the samples. FKOs from the InP emitter region were observed in the wafer with low recombination forward current at the emitter-base (E/B) heterojunction. In contrast, they did not appear when recombination current was dominant. The absence of the FKOs from the emitter indicates the high concentration of the recombination centers at the E/B heterojunction. We have also measured PR spectra from InAlP/GaAsSb/InP DHBT wafers. Pronounced FKOs from InAlP emitter reflect the suppression of recombination at E/B heterojunctions.

Characterizations of transparent Schottky barrier GaN and AlGaN UV detectors in the vacuum UV (VUV) and soft X-ray (SX) region using synchrotron radiation are described. In the GaN UV detectors, the responsivity achieved about 0.05 A/W at 95 eV (13 nm). Thus, their device performance is shown between 3.4 and 100 eV (10 and 360 nm). Furthermore, the high responsivity spectra were realized by using AlGaN Schottky UV detectors consisting of Al0.5Ga0.5N on AlN epitaxial layer.

This paper studies the decomposition characteristic of group-III sources during InAlAsSb growth on InP substrates by metalorganic chemical vapor deposition (MOCVD) using trimethylindium (TMI), trimethylaluminum (TMA), trimethylantimony (TMSb) and arsine (AsH3). A composition analysis of InAlAsSb layers shows that the group-III compositions in the InAlAsSb layer change remarkably when the flow rate of the group-V source is varied. To clarify the reason for this phenomenon, the growth rates of InAsSb and AlAsSb component are examined. Their changes indicate that TMSb suppresses the decomposition of TMA while AsH3 enhances it. Moreover, the HEMT structure with InP/InAlAsSb Schottky barrier layer, whose InP layer acts as a recess-etch-stop layer, is fabricated for the first time. The I-V characteristics of a fabricated Schottky barrier diode indicate that the reverse leakage current of InP/InAlAsSb is about one order of magnitude smaller than that of commonly used InP/InAlAs.

We have studied the crystalline and electrical properties of AlInN/GaN superlattices (SLs) and strained AlN/GaN SLs on GaN grown by metalorganic vapor phase epitaxy. A (0001) sapphire substrate was used. The SLs were grown using N2 carrier gas. X-ray analysis showed the eighth order satellite peak in AlInN/GaN SLs. Hall measurement showed an electron mobility of 946 cm2/Vs at highest (a sheet carrier density of 2.9x1012 cm-2) for AlInN/GaN 5SLs on GaN at 295K, and showed a value of 11432 cm2/Vs (1.99x1012cm-2) at 170K, and a value of 2610 cm2/Vs (3.38x1012cm-2) at 295K for AlN/GaN 10SLs on GaN.

The effects of gas temperature gradient, pulse discharge modulation, hydrogen dilution, gas flow, and substrate materials on growth of clusters below about 10 nm in size in silane parallelplate RF discharges are studied using a high-sensitivity photon-counting laser-light-scattering (PCLLS) method. Thermophoretic force due to the gas temperature gradient between the electrodes drives neutral clusters above a few nm in size toward the cool RF electrode. Pulse discharge modulation is much more effective in reducing the cluster density when it is combined with the gas temperature gradient, and clusters above a few nm in size cannot be detected by the PCLLS method even for the discharge over a few hours. Hydrogen dilution and gas flow are also effective in suppressing growth of clusters, when the H2/SiH4 concentration ratio is above about 5 and the flow velocity is above about 6 cm/s, respectively. Cluster growth rate with a glass or Si substrate is found to be considerably higher than that without the substrate.

Effects of H irradiation on purifying Cu films and improving their surface roughness as well as size and orientation of Cu grains in the films have been examined using a newly developed plasma CVD reactor equipped with an H atom source, in which Cu(hfac)2 is supplied as the source material. The H irradiation is effective in purifying the Cu films, increasing the grain size, and reducing the surface roughness, while it has no effect on the grain orientation. The decrease in dissociation degree of material gas leads to reduction of the surface reaction probability of Cu- containing radicals, which is important to realize conformal deposition in fine trenches. Using the control of dissociation degree of material gas independent of H irradiation, we have demonstrated conformal deposition of smooth Cu films in the trench using the developed plasma CVD reactor.

Magnetic Compton profiles (MCPs) of a DyCo5.4 single crystal were measured at 10 K, 200 K and 300 K. The temperature dependence of the spin moment, which is deduced from the areas under the normalized MCPs, is significantly different from that of the total magnetization measured by a superconducting quantum interference device (SQUID). This difference is due to the presence of a substantial amount of the orbital moment on a Dy site that does not contribute to the magnetic Compton scattering cross section. The analysis of the MCPs reveals that the absolute value of the spin moment increases with increasing temperature and that the spin magnetic moment of the conduction electrons has an opposite sign to the total spin magnetization in the covered range of temperature.

Orthorhombic β-FeSi2 thin-films were prepared on Si(100) and Si(111) substrates by a pulsed laser deposition method. When the substrate temperature was 500°C, β-FeSi2 thin-films were grown on Si(100) and Si(111) substrates. The thin-films grown on Si(100) and Si(111) substrates were polycrystalline and monocrystalline structures, respectively. The values of band-gap energy calculated from transmittance measurements were 0.71-0.72 eV. From Raman scattering measurements, it was found that the distortion due to the lattice mismatch between a β-FeSi2 thin-film and a Si substrate originates in the β-FeSi2/n-Si interface. Moreover, the fine crystals of β-FeSi2 existed in an amorphous thin-film which was grown on Si(111) substrate at room temperature (RT).

From van der Pauw measurements, conduction type, carrier concentration and Hall mobility were p-type, 1018-1021 cm−3 and 200-500 cm2/Vsec, respectively. The p-n diode characteristics of these heterostructure diodes were investigated by I-V and C-V measurements. The results indicate that the carrier distribution agrees with an ideal one-sided slope junction.