摘要:

We have studied the effect of source species, substrate temperature, substrate orientation, and group‐V overpressure on the growth rate and composition of GaAs and InGaAs alloys grown by chemical beam epitaxy. Our results for GaAs growth rate versus substrate temperature show a significant effect of group‐V overpressure on the details of this dependence. The incorporation of gallium from triethylgallium into GaInAs alloys is found to be strongly dependent on temperature and alloy indium concentration, but independent of the source of indium. It is also significantly dependent on group‐V overpressure. We could find no effect on growth rate or composition dependence between growth on nominally (100) GaAs and InP substrates, and those cut 2° or 3° off axis.

ISSN:0021-8979    

DOI:10.1063/1.345401

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Band filling effects are used to modify the absorption and refractive index of bulk GaAs/Ga1−xAlxAs layers in a Bragg reflector in the wavelength region between the band gap of the two materials. Significant reflectivity modifications are observed in a subpicosecond regime.

ISSN:0021-8979    

DOI:10.1063/1.345402

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present numerical simulations of broad‐area semiconductor lasers with smooth spatial filtering at the output facet. The beam‐propagation and Prony methods are used to calculate the beam characteristics and discrimination against higher‐order lateral modes of the laser devices. With an output facet having a Gaussian reflectivity profile, the fundamental lateral mode is favored. Discrimination between the two lowest‐order modes increases significantly with narrow reflectivity profiles.

ISSN:0021-8979    

DOI:10.1063/1.345403

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report on the measurement of the millimeter wave transmission properties of a dielectric waveguide with a YBa2Cu3O6+xboundary layer. The transmitted power and phase shift of a 94 GHz signal propagating through the dielectric waveguide structure was measured over the temperature range of 77–150 K. The transmitted power was observed to depend upon temperature due to the dissipation of the millimeter wave signal in the YBa2Cu3O6+xboundary layer. Thereby the temperature dependence of the normal‐state ac conductivity was measured. The experimental data were fitted to a Drude model for the normal‐state ac conductivity of the YBa2Cu3O6+x. The temperature dependence of the Drude scattering time was obtained. The scattering time was found to decrease with decreasing temperature and was 7.5–11.2 ps in magnitude.

ISSN:0021-8979    

DOI:10.1063/1.345404

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A previous model for phosphorus diffusion in silicon [J. Appl. Phys.65, 2243 (1989)] is extended to include four additional reactions among substitutional phosphorus, silicon self‐interstitials, vacancies, and phosphorus‐defect pairs. All reaction rates in the model are based on physically plausible kinetic estimates. The numerical solution to the resulting system of eight coupled partial‐differential equations yields profiles in good agreement with experiment.

ISSN:0021-8979    

DOI:10.1063/1.345405

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Intersubband transitions in modulation doped, arbitrary potential profile quantum‐well structures under an applied field are analyzed by solving the Schro¨dinger and Poisson equations self‐consistently. This analysis is applied to the local‐to‐global transitions of a step well structure. The results show that although the band‐bending effect is significant (∼25 meV) at a relatively high carrier density of 5.6×1011/cm2(∼3×1017/cm3), the transition energies and absorption coefficients remain close to the flat band cases. This calculation confirms that the local‐to‐global transitions have large linear Stark shift and oscillator strength even at high doping.

ISSN:0021-8979    

DOI:10.1063/1.345375

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Herein we report the results of an investigation of the trajectories of horizontally coplanar droplet pairs of similar charge, falling under the influence of gravity, drag, and electrostatic forces. Experiments were conducted using ethanol droplets that were generated electrostatically from the tips of two parallel needles. These droplets were subject to an external electric field and an initial electrostatic force in the vertical, downward direction, and an interdroplet electrostatic repulsive force in the horizontal direction. A model was developed to predict the measured trajectories. Within the range of applied potential differences investigated (from 1–3 kV), the theory and experiment were found to agree to within approximately 5%. The results also showed that the droplet trajectory was influenced noticeably by the axial electrostatic force on the droplet as it departed from the needle.

ISSN:0021-8979    

DOI:10.1063/1.345376

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We show that the gravitational‐wave‐induced electric field in a superconducting antenna coupled to a reconant inductance transducer is much smaller than that in a superconducting antenna without a transducer. The superconductivity property of a superconducting antenna produces an addtional shift in the resonant frequency of the displacements which might be detectable, although it is small.

ISSN:0021-8979    

DOI:10.1063/1.345377

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.345378

出版商:AIP    

年代:1990

数据来源: AIP