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We present a systematic study of temperature-dependent reflectance (R) and photoluminescence (PL) measurements on ZnMnO films grown by plasma-assisted molecular beam epitaxy. For the first time, the three free-exciton transitions FXA (Γ7c-Γ7vu), FXB (Γ7c-Γ9v), and FXC (Γ7c-Γ7vl) and the longitudinal-optical phonon replicas of FXB and FXC of ZnMnO films have been clearly observed in the R spectra. The parameters describing the activation energy and the temperature dependence of the transition energy and broadening have been extracted by fitting the experimental R and PL spectra. The spectral data of ZnMnO films not only show the deterioration of crystalline quality with increasing Mn composition fraction but also indicate the Mn clustering caused by Mn atom segregation. [ABSTRACT FROM AUTHOR]

The lattice parameter and electronic structures of CoSi and CoSi1-xYx (Y=Al and P, x=0.031 25 and 0.125) were calculated using the full-potential linear augmented plane wave approach based on density functional theory. The calculated lattice parameter of binary CoSi is about 0.27% smaller than the experimental value. Calculated electronic structures show that CoSi is a semimetal and its density of states is very small at the Fermi level. Doping with Y on the Si site can tune the Fermi level and the effective masses as well as the density of the hole carriers or electron ones in the electronic structure of CoSi, which is a valuable way to modulate the transport properties of this compound. Based on the calculated electronic structures and our experimental results on CoSi, the intrinsic relations between the electronic structures and transport properties of doped and undoped CoSi are discussed in detail. [ABSTRACT FROM AUTHOR]

Thermoelectric transport properties of CoSi1-xAlx single crystals have been measured over the temperature range from 300 to 973 K to investigate the effects of Al substitution on the electrical resistivity, Seebeck coefficient, and thermal conductivity. The solubility limit of Al substitution for Si in CoSi is found to be in the range of 0.2<=x<0.3. The electrical resistivity increases with increasing Al substitution x and reaches a maximum at x=0.08. When x is further increased, there is a drop in the electrical reisitivity between 300 and 550 K and there is almost no change at higher temperatures. The Seebeck coefficients of CoSi1-xAlx single crystals shift towards the positive direction compared to that of the binary crystal over the entire measured temperature range. The Seebeck coefficient decreases as a function of temperature. The thermal conductivity and the figure of merit decrease significantly with increasing Al content. The decrease in thermal conductivity is mainly attributed to the additional scattering from Al atoms. [ABSTRACT FROM AUTHOR]

We have studied the microstructure of SrTiO[sub 3] films on LaAlO[sub 3] substrates with the SrRuO[sub 3] buffer layer using high-resolution transmission electron microscopy. While high density of defects due to lattice mismatch were found at the SrRuO[sub 3]/LaAlO[sub 3] interface, no misfit dislocation was observed at the SrTiO[sub 3]/SrRuO[sub 3] interface. The {111} stacking fault in the SrRuO[sub 3] buffer layer propagates into the SrTiO[sub 3] film, giving rise to a type of antiphase boundary on the {110} plane with a crystallographic shear vector of a/2<001>. The boundary is a conservative one which does not lead to any charge defects. A model based on dislocation interactions is proposed to explain the generation mechanism of the antiphase boundary. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Focuses on a study which proposed a novel operation in the vertical integration of double-barrier resonant tunneling structures (DBRTS) in which the negative differential resistance region can be repeated. Applications of DBRTS; Cross section of the vertically integrated DBRTS; Characteristics of a finished device.

Determines the aluminum (Al) composition of AlGaAs by various methods. Preparation of the AlGaAs layers; Way to obtain the Al mole fraction; Purpose of the reflection high-energy electron diffraction intensity oscillation; Formula for the Al mole fraction of the AlGaAs from the photoluminescence method.

We report on the study of high frequency magnetotransport properties of the chromium dioxide (CrO[sub 2]) thin films, grown on Si substrate using chemical vapor deposition. The film exhibits a ferromagnetic transition with a Curie temperature near 390 K. The temperature dependent spontaneous magnetization follows Bloch's law. The impedance spectra, being analyzed based on the fundamental electrodynamics, are demonstrated to be in a low-loss dielectric limit along with the occurrence of dielectric relaxation and magnetization response. The specific features of impedance spectra, distinct from the usual metallic ferromagnet, are attributed to the half metallic nature of CrO[sub 2]. The results explore the possibility for high frequency device applications. [ABSTRACT FROM AUTHOR]

Presents a study which developed a novel fabrication technique for indium gallium arsenide/gallium arsenide strained-layer buried heterostructure lasers. Methods; Experimental results; Benefits from the developed technique.

We present a systematic study of temperature-dependent reflectance (R) and photoluminescence (PL) measurements on ZnMnO films grown by plasma-assisted molecular beam epitaxy. For the first time, the three free-exciton transitions FXA (Γ7c-Γ7vu), FXB (Γ7c-Γ9v), and FXC (Γ7c-Γ7vl) and the longitudinal-optical phonon replicas of FXB and FXC of ZnMnO films have been clearly observed in the R spectra. The parameters describing the activation energy and the temperature dependence of the transition energy and broadening have been extracted by fitting the experimental R and PL spectra. The spectral data of ZnMnO films not only show the deterioration of crystalline quality with increasing Mn composition fraction but also indicate the Mn clustering caused by Mn atom segregation. [ABSTRACT FROM AUTHOR]