摘要:

Schottky-type light emitting devices have been fabricated on Er-oxide doped Si layers grown by molecular beam epitaxy, in order to study the light emission process of Er-doped Si structures. By applying a reverse bias on the Schottky junction, Er ions incorporated within the depletion layer can be electrically excited via a hot electron impact process. Rather intense electroluminescence (EL) at a wavelength of 1.54&mgr;m has been observed at room temperature. The optoelectronic properties of the devices have been characterized by both input-power dependent and temperature dependent EL measurements. An activation energy value of∼160 meV responsible for luminescence thermal quenching has been obtained. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119715

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Longitudinal single mode emission from ZnSe-based laser diodes with first order distributed Bragg reflectors has been achieved. The emission energy could be varied in the green spectral range over more than 80 meV by changing the grating period from 97.7 to 102.2 nm. The variation of the lasing threshold current in this range is explained as a consequence of the optical gain spectrum of the structure. Wavelength fine tuning with a rate of&Dgr;&lgr;/&Dgr;T=2.9×10−2 nm/Kwas realized by temperature variation. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119716

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The magnitude of the third-order nonlinear polarizability &ggr; of armchair nanotube is theoretically studied. The calculated results for theC70tube are consistent with those measured by Neher &etal; [Opt. Lett.17, 1491 (1992)]. The static and dynamical magnitudes of &ggr; can be greatly enhanced by increasing the carbon number. When the carbon number is big enough, the major dynamical response peaks with large &ggr; magnitudes are located at the optical frequency &ohgr; near the energy gapEg(i.e.,3&ohgr;∼3Eg), and the highest peak magnitude is much larger than that ofC70,which is important in practical use. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119717

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on a remarkably large second-harmonic generation (SHG) in a germanosilicate glass (15.7GeO2–84.3SiO2in mol &percent;), which was induced by poling while the sample was irradiated with the ArF laser at the wavelength of 193 nm. The SHG coefficient,d,thus induced was measured at various poling electric-field strengths using the Maker-fringe technique. The value ofdincreases with increasing poling field and then saturates around1.5×105V/cm. The largestdcoefficient value obtained in this work, which is 3.4±0.3 pm/V, seems to exceedd22ofLiNbO3.Furthermore, polarization dependence of the induced SHG shows an anisotropy of the refractive index. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119718

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The temporal evolution of the plasma sheath in a small cylindrical bore in the presence of an auxiliary electrode is determined for different electrode radii. The ion density, velocity, flux, dose, ion energy distribution, and average impact energy are calculated by solving Poisson’s Equation and the equations of ion motion and continuity using finite difference methods. The particle-in-cell method is also used to confirm the validity of the data. Our results indicate that more ions will attain high impact energy when the auxiliary electrode radius is increased, but the dose will decrease. Our results suggest that the normalized auxiliary electrode radius should range from 0.10 to 0.30 in order to maximize the dose and produce a larger number of ions with higher impact energy. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119719

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The mechanism of electron-beam-induced selective thermal decomposition of ultrathin oxide layers on Si surfaces was studied by scanning reflection electron microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy. We found that the change in the oxide layer composition caused by electron-stimulated oxygen desorption accounted for the selective thermal decomposition, where nanometer-scale voids were densely generated at a low heating temperature (720 °C). This implies that oxygen desorption from the oxide layers promotes the formation of a volatile oxide (SiO), and generates void nucleation sites. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119720

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on the thin films of solid–solution material(1−x)SrBi2Ta2O9−xBi3Ti(Ta1−yNby)O9fabricated by a modified metalorganic solution deposition technique for ferroelectric random access memory devices. Using the modified technique, it was possible to obtain the pyrochlore free crystalline thin films at an annealing temperature as low as 600 °C. The solid–solution of layered perovskite materials helped us to significantly improve the ferroelectric properties, higherPrand higherTc,compared toSrBi2Ta2O9; a leading candidate material for memory applications. For example, the films with 0.7SrBi2Ta2O9–0.3Bi3TiTaO9composition and annealed in the temperature range 650–750 °C exhibited2PrandEcvalues in the range 12.4–27.8&mgr;C/cm2and 68–80 kV/cm, respectively. The leakage current density was lower than10−8 A/cm2at an applied electric field of 200 kV/cm. The films exhibited good fatigue characteristics under bipolar stressing. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119721

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The surface of the epitaxial layer of AlP grown by atomic layer epitaxy (ALE) was observed by atomic force microscopy. It was discovered that the atomic scale surface flatness was not always retained during ALE growth even though the self-limiting growth of 1 monolayer per 1 alternative source gas supply was maintained. A reaction process model that focused on the methyl adsorbate lifetime on the Al surface was proposed to explain the experimental results. Based on this model, AlP surface morphology was improved by gas feeding control, and a flat surface with atomic steps was obtained even after 250 cycles of the ALE sequence. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119722

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Highly conductive metallic oxide thin films ofSrRuO3with single crystalline quality have been grown on (001)SrTiO3by using pulsed laser deposition. The films have a[00l] orientation with an in-plane relationship of[110]SrRuO3 // [100]SrTiO3.They have excellent metallic behavior with room temperature resistivity of∼310&mgr;&OHgr; cm and a residual resistance ratio of about 7 at 4.2 K, the largest reported to date. A clear ferromagnetic transition at∼147 K was detected by resistivity and magnetic measurements. However, the transition becomes blurred as the density-of-point defects increases in the films following a 400 keV proton irradiation with an accumulative dose up to∼6.0×1016 ions/cm2.©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119723

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Intermediate anchorings of nematic liquid crystals onto substrates are now intensively studied essentially because of their potential display applications. Here, we use the active oxygen gas arising from a plasma reactor to realize progressive chemical modifications of glass substrates covered with silane. In this manner, the dispersive and nondispersive surface tensions of the substrate are gradually modified involving a continuous change in the differential wetting properties of the substrate with both parts of the liquid crystal molecules, and in the anchoring energy. Intermediate anchorings with tilted angles are thus obtained in the vicinity of an anchoring transition from the pseudohomeotropic to the planar alignment, where symmetry is broken. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119724

出版商:AIP    

年代:1997

数据来源: AIP