Search

Red thin-film phosphors were fabricated based on a ZnO:(La,Eu)OF nanocomposite structure where (La,Eu)OF nanoparticles were dispersed in a ZnO film matrix. The films were deposited on glass substrates by a sol-gel method at a low temperature of 600 °C using trifluoroacetic acid as a fluorine source. Doping gallium into the films suppressed the grain growth of ZnO, increased the optical band gap, and decreased electrical resistivity, which indicates that Ga[SUP3+] was selectively incorporated into the ZnO lattice. Eu[SUP3+] was practically doped in the LaOF lattice. As a result, strong red emissions due to the [SUP5]D[SUB0] → [SUP7]F[SUB2] transition of Eu[SUP3+] were observed in both photo- (PL) and cathodoluminescence (CL) measurements. The efficiency of ultraviolet light excitation at 274 nm was promoted by the charge transfer from O[SUP2-] to Eu[SUP3+] in PL. Ga doping was found to increase the CL intensity of the film, which was attributed to suppression of charge accumulation on the films. [ABSTRACT FROM AUTHOR]

Presents a model that allows a consistent description of growth evolution on nonplanar surface by molecular beam epitaxy and metalorganic vapor-phase epitaxy. Basic equations for epitaxial growth; Formulation for a nonplanar surface; Anisotropy of growth rate.

Focuses on a study that investigated the influence of negative ions on the structure in radio frequency glow discharges in SiH[sub4]/H[sub2] by spatiotemporal optical emission spectroscopy. Method used to synthesize thin films; Description of the experimental apparatus used; Minimum sustaining voltages in various gases measured.

Presents a study that analyzed temperature dependencies of Hall mobility of nondoped and nitrogen-doped n-type β-silicon carbide films using a conventional theoretical model. Kinds of films used in the experiment; Equations for piezoelectric-mode lattice scattering; Calculation of conductivity mobilities for impurity scattering.

The confinement properties of an electron to a two-dimensional quantum disk surrounded with a finite-height potential barrier are investigated. It is shown that since the confining barrier is distorted by a centrifugal potential arising from nonzero electron angular momentum, the electron can tunnel out through a thin part of the distorted barrier, which takes place when the radius of the disk is smaller than a critical radius. It is found that since the barrier for zero electron angular momentum is deformed by a centripetal potential characteristic of two dimensions, although no electron leaks out at any radii, bound-energy levels ascend as the disk radius decreases and become tied up at the top of the confining potential well, resulting in high density of states. Some experimental methods are outlined to observe those leaky and confining phenomena. [ABSTRACT FROM AUTHOR]

Examines the epitaxial growth of organic materials on hydrogen terminated vicinal surfaces of silicon(111). Use of multiple-azimuth reflection in describing molecular arrangement of the films; Conversion of reflection high energy electron diffraction to low energy electron diffraction; Presence of Debye-Waller type in substrates.

Investigates the time development of electron temperature in multiple quantum well (MQW)-semiconductor laser amplifier. Observation of time development in amplified spontaneous emission spectrum; Rise of electron temperature; Carrier transport in MQW structures for semiconductor laser applications.

Electrical properties of non-doped and nitrogen-doped n-type β-SiC films grown on Si substrates have been investigated at 70–1000 K. Those of non-doped films remarkably depend on the Si/C ratio of the source gases. The highest mobilities of non-doped films are 510 and 1330 cm2 V-1 s-1 at 296 and 71 K, respectively. The carrier concentrations are as low as 6×1016 cm-3 even at 1000 K. Ionization energies of 34 –37 meV for nitrogen donors and 19–25 meV for unknown donors of non-doped films are obtained. Mobilities of both non-doped and nitrogen-doped films are dominated by lattice scattering at high temperatures and by impurity scattering at low temperatures. Nitrogen donors strongly affect the impurity scattering. [ABSTRACT FROM AUTHOR]

Presents a study which analyzed experimentally and theoretically the turn-off characteristics for tandem-electrode bistable laser diodes. Experiment; Theory and discussion; Conclusion.

Presents a study wherein Si[sub1-x]C[subx] thin films were prepared by glow discharge method in a hydrogen-rich atmosphere at low substrate temperature. Superior properties of microcrystalline silicon to hydrogenated amorphous silicon; Measurement of the properties of Si[sub1-x]C[subx] thin films; Description of the reflection high-energy electron diffraction and optical absorption.

Replies to a comment by Segall et al on the article 'Temperature dependence of electrical properties of non-doped and nitrogen-doped beta-SlC single crystals grown by chemical vapor deposition.' Agreement with the commenters' choice of 0.346 as a reasonable value for the density-of-state effective mass for a single-band minimum; Opposition to the suggestion that donors in non-doped films are nitrogen.

Deals with a study which investigated radio frequency glow discharges in methane and hydrogen by spatiotemporal optical emission spectroscopy. Background to the study; Experimental method; Results and discussion.

Focuses on a study which examined the dependence of the characteristics of β-silicon carbide Schottky diodes on the Schottky metal and crystals grown by chemical vapor deposition. Sample preparation; Current-voltage measurements.

Cross-sectional potential distribution of a GaN-based field effect transistor with a field-modulating plate has been measured by Kelvin prove force microscopy to investigate the effect of the field-modulating plate on an electric field under high-voltage biasing conditions. The observed potential distribution clearly revealed that the introduction of the field-modulating plate is effective in relaxing the peak electric field intensity at the drain side of the gate edge. Furthermore, the authors experimentally observed that the peak of electric field splits into two positions: drain-side edges of the gate and field-modulating plate electrodes. [ABSTRACT FROM AUTHOR]

Nucleation and growth kinetics of AlN films on atomically smooth 6H-SiC (0001) surfaces, which were obtained by HCl etching at elevated temperatures prior to growth, were investigated. The surface morphology and the defect density of AlN films on such surfaces were significantly improved compared to those on as-received SiC surfaces. This is due to enhanced diffusion length and reduced incoherent boundaries at the coalescence regions of the AlN islands. AlN nuclei on the as-received SiC surface were crystallographically misaligned and thus induced incoherent boundaries at the coalescence stage, resulting in the delay of the two-dimensional growth mode transition and defect formation in AlN films. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Measures the changes in indium gallium arsenic phosphide quantum well conduction- and valence-band edge energies due to tensile strength. Control of the ratio of band discontinuity; Accordance of experimental values with simple calculation; Impact of longer diffusion length on hole distribution.

Stacking faults of cubic SiC films grown on Si (100) were investigated by the electrolytic etching. We find an exponential reduction of the defect density with an increase of film thickness and the anisotropy in the density for the films on off-axis Si (100) substrates. The defect reduction along the offset direction <011> is explained from the atomic step effect limiting the length of stacking faults to smaller than the equilibrium value. In addition, the defects are eliminated by controlling the film thickness and the size of the growth area using patterned substrates. Since the defects in SiC are metastable, the film thickness required for defect-free crystal is larger than [Square_Root]2× the lateral dimension. [ABSTRACT FROM AUTHOR]

Epitaxial growth of β-SiC on Si(511) substrates has been carried out. Single-crystalline β-SiC films without warpage and cracking are grown by chemical vapor deposition. The epitaxial orientation of the film is determined using x-ray precession camera. The orientation is inclined as SiC(411)//Si(511) coincident with the [011] axis, which should be compared with the parallel epitaxial growth on Si(100) or Si(111). [ABSTRACT FROM AUTHOR]

Step bunching on 6H-SiC (0001)-vicinal face etched by HCl at 1300-1500 °C is investigated by atomic force microscopy. When the substrate has the inclination toward near <011¯0> or even <112¯0>, continuous parallel and periodic microsteps with six-bilayer height are laid perpendicular to the off direction, although those perpendicular to <112¯0> are apt to decompose into three bilayer or less. Formation mechanism of unit-cell-height steps is discussed based on consideration of bond configuration at step edges. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]