摘要:

We propose an intersubband‐based frequency‐mixing device in which phase matching is imposed electrically. The dynamic tuning considerably relaxes fabrication tolerances, allows compensation for the intensity dependence of the index, and enables phase‐matched operation at a range of degenerate and nondegenerate pump wavelengths. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115404

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A set of the different Si:Al and Si:B surface phases capped by amorphous Si layers were grown by molecular beam epitaxy (MBE). The formation of the buried interfaces was studied by low‐energy electron diffraction and Auger electron spectroscopy. The conductivity and Hall effect measurements of the grown samples revealed that only the buried Si(111)&sqrt;3×&sqrt;3−B surface phase manifests itself as a highly doped degenerated layer, while all the buried Si:Al surface phases covered by amorphous Si show negligible activation of dopants. The difference in electrical properties of the buried surface phases are discussed in terms of the characteristics of their atomic structure. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115405

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The specific volumes of molten Pd40Ni40P20, Pd77Cu6.5Si16.5, Pd82Si18, and Ni80P20, which are all glass formers, and were measured near the liquidus. It was found that the ratio &agr;/Tg, where &agr; is the thermal expansion coefficient andTgis the glass transition temperature, remains fairly constant for all these systems. The scaling follows from the fact that with a larger thermal expansion coefficient, the free volume of the molten system would be squeezed out faster resulting in a largerTg. This scaling behavior also allows us to roughly predict the glass transition temperature of a glass forming system. The glass forming ability can also be predicted by a parameter defined as &agr;/T1. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115406

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The solidification behavior of germanium quenched from the melt at pressure of 2–7 GPa is presented. The solidification parameters of specimen were directly measured under high pressure. The microstructure of specimen was observed by electron microscopy. From the measured undercooling and average grain size, the interfacial free energy and activation energy of crystal growth under high pressures were estimated according to classical nucleation theory. Using high resolution transmission electron microscopy (HRTEM), crystals of sizes ranging from 5 to 100 nm surrounded by an amorphous matrix of germanium were found in those samples which quenched from deeply undercooled melt. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115407

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Applicability of a one‐dimensional reaction‐diffusion model (ORDM) as a tool for analyzing the gas–solid phase transition rate process during chemical vapor deposition is tested by comparing its results with those predicted by a simple Monte Carlo method. The results reveal that the ORDM is applicable when the conditions of Knudsen number (Kn)<0.03, aspect ratio (As)≳1.0, and reactive sticking coefficient (&eegr;)<0.1 are fulfilled. At large Kn and large &eegr;, the ORDM gives quite an erroneous result. The ORDM is also applicable to predict the grown film shape when &eegr;<0.1, Kn ≫1.0, and As≳2.0. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115408

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The temperature and frequency dependences of the pyroelectric current have been studied in Nylon 7 and Nylon 11 ferroelectric polymer films. A remarkable change of value of the pyroelectric currents near the glassy transition temperature (Tg) was observed. Analyses of experimental data show that the temperature behavior of pyroelectric currents can be explained by the competition of the primary and secondary effects. Currents due to these effects have different signs. BelowTg, the dominant component of the pyroelectric current is primary pyroelectricity, and aboveTgthe secondary effect becomes dominant. Mechanisms producing pyroelectric currents in Nylon 7 and Nylon 11 are discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115409

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have applied two photothermal techniques (infrared radiometry and mirage) and conventional procedures to measure the thermal diffusivity of a highly anisotropic sample of pyrolytic graphite. Unexpected and strongly differing results are obtained with each technique. A theoretical analysis indicates that whereas the mirage technique gives a measure of the elements of the thermal diffusivity tensor, infrared radiometry yields the elements of another thermal magnitude represented by the inverse of this tensor. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115410

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Interfacial roughness parameters and lattice strain of Si0.4Ge0.6films with varying thickness epitaxially grown on Si(100) were determined using the techniques of grazing‐incidence x‐ray scattering and diffraction. The roughness ofboththe buried interface and sample surface follows a similar power‐law scaling behavior with an exponent &bgr; around 0.71 for films below the critical thickness, and it undergoes a large change above the critical thickness. Observation of such a scaling law thus establishes a quantitative correlation between the interfacial roughness and lattice strain, and also allows the prediction of interfacial roughness as a function of film thickness of this compound. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115411

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Isolated diamond particles grown by chemical vapor deposition on a mirror‐polished Si substrate have been studied by cross‐sectional transmission electron microscopy. Focused ion beam micromachining enabled the cross‐sectional specimen to be carved out precisely at the center of the particle. Atomic scale observation of the diamond/Si interface revealed the presence of an ∼3 nm thick amorphous intermediate layer including a few pits around the nucleation site of the particle. Growth mechanism and relationship between growth orientation and internal defect structure of the diamond particle are discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115185

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The up‐converted hot luminescence technique was utilized to obtain information on the nonradiative relaxation in Ni2+:MgO. The experiment shows the presence of an electronic bottleneck associated with the3T1(t4e4) electronic state which was determined to be at 2.973±0.003 eV (23978±25 cm−1). The spectral profiles indicate that the 395±15 cm−1phonon mode is involved in the nonradiative relaxation of the impurity Ni2+ions. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115186

出版商:AIP    

年代:1995

数据来源: AIP