摘要:

Infrared spectroscopic ellipsometry (IRSE) over the wavelength range from 700 to 3000cm−1has been used to study and distinguish the microstructure of polycrystalline hexagonal and cubic boron nitride thin films deposited by magnetron sputtering onto (100) silicon. The IRSE data are sensitive to the thin-film layer structure, phase composition, and average grainc-axes orientations of the hexagonal phase. We determine the amount of cubic material in high cubic boron nitride content thin films from the infrared optical dielectric function using an effective medium approach. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118655

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Near-field Raman spectroscopy has been performed on liquid CCl4. The spectrum, obtained through an aperture significantly smaller(&lgr;/10)than the exciting wavelength (514.5 nm) with a good signal-to-noise ratio, presents polarization effects that are different from the far-field spectrum. The tip is shown to be polarized at 99.9&percent; by the Raman near field. If the probe is modeled as a single dielectric sphere, the estimated Raman near-field amplitude amounts to about103V m−1. The frustration of the Raman near field by the probe allows to record the Raman spectrum of only 0.4 attomol, or 240 000 mol. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118665

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In this work, the thermoluminescence response of &agr;-Al2O3under solar irradiation has been studied. This material exhibits selective excitation with a narrow response, with a maximum at 313 nm, in the ultraviolet-B range. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118200

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Explosive wire induced surface flashover has been studied as a promising method for destruction of solid materials. This method exhibits very high efficiency of electric energy transformation into the discharge and effective shock wave generation. The framing photography method is applied in order to clarify the discharge dynamics and the mechanism of the shock wave formation and propagation. The experiments performed allow to suggest the model of the pressure wave generation in the wire explosion process. ©1997 American Institute of Physics.   

ISSN:0003-6951    

DOI:10.1063/1.118666

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have found that a cyclic crystalline–amorphous phase transformation can occur inCo75Ti25alloy powder when subjected to ball milling. The results have shown that a single amorphous phase ofCo75Ti25is obtained after 11 ks of mechanical alloying (MA) time. This amorphous phase transforms into a new metastable phase ofbcc-Co3Tiupon milling for 86 ks. Thebcc-Co3Tiis thermally stable and does not transform to any other phase(s) upon heating up to 1300 K. It however returns to the same amorphous phase ofCo75Ti25upon milling for 360 ks. Further milling leads to the formation of crystalline and/or amorphous phases depending on the MA time. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118667

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report the growth of continuous diamond thin films by bias-assisted hot filament chemical vapor deposition onto hexagonal boron nitride films prepared by plasma chemical vapor deposition on silicon substrates. Negative substrate biasing during the early stages of diamond growth greatly increased the nucleation density. Values of1010 cm−2were achieved at −250 V for bias times as short as 25 min. After the nucleation stage, high quality polycrystalline continuous diamond films, as revealed by scanning electron microscopy and Raman analysis, were grown under standard hot filament deposition conditions. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118668

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Presented here is proof-of-principle that a thin single crystal semiconductor film—when twist-wafer bonded to a bulk single crystal substrate (of the same material)—will comply to the lattice constant of a different single crystal semiconductor thick film grown on its surface. In our experiment, a 100 Å film of GaAs was wafer bonded to a GaAs bulk substrate, with a large twist angle between their ⟨110⟩ directions. The resultant twist boundary ensures high flexibility in the thin film. Dislocation-free films ofIn0.35Ga0.65P(∼1&percent; strain) were grown with thicknesses of 3000 Å, thirty times the Matthews–Blakeslee critical thickness, on twist-wafer-bonded films of GaAs. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118669

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In this study we propose a model that describes the diffusion of copper, hydrogen, and titanium through the liquid/solid interface in potassium lithium tantalate niobate crystals. Copper and hydrogen ions may occupy potassium/lithium vacant sites. Hydrogen ions are also able to stay at tantalate/niobate vacant sites in the presence of titanium. This model shows that the hydrogen concentration can be dramatically reduced in KLTN:Cu,X,Ycrystals (whereX, Yare any first row transition metals but not Ti or Cu), and is in agreement with experimental results. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118670

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Different growth stages and the microstructure of amorphous CuTi films are investigated by scanning tunneling microscopy and small angle neutron scattering. During film growth at room temperature, the initially smooth films show increasing surface roughening and finally a change to a columnar growth mode with column diameters of about 20 nm. The interfacial energies associated with the column boundaries are higher than those of grain boundaries in crystalline systems. The column boundaries might be the origin of high intrinsic tensile stresses measured before in the amorphous CuTi films. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118671

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Ag particles of 4.2 nm mean diameter have been formed inside a glass matrix, doped with silver by ion exchange, by electron beam irradiation of the glass cut into thin slices by ultramicrotomy. By this treatment, a high concentration of particles which are homogeneously arranged throughout the glass and exhibit a narrow size distribution is achieved (volume fraction of particulate silver:3.5×10−2).The interface stress reflecting the particle/matrix interaction is comparable to that of isolated Ag particles. This new route of synthesis will allow to generate materials with strong third order nonlinear susceptibility. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118672

出版商:AIP    

年代:1997

数据来源: AIP