摘要:

Resonance characteristics of a glass micropipette near a mica surface have been investigated as functions of the tip–surface distance,D, and of the ambient humidity,H. With decreasingD, the resonance frequency of the tip increases, while its resonance amplitude decreases. The resonance curve is almost symmetric except in the close vicinity ofD=0,at which the oscillation is damped completely. The effective length,D0,of the tip–surface interaction is independent of the dither amplitude. With increasingH,D0decreases gradually, exhibiting a rather sharp drop aroundH=40&percent;.These results indicate that, for largeDwhere the direct contact does not occur, some noncontact force between the tip and the surface is operative, and that this force is sensitive to the presence of a water layer on the surface. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119604

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Multilayer films composed of piezoelectrically active ZnO and inactiveAl2O3layers were prepared on silicon by a pulsed laser deposition technique. The ZnO layers were completely (001) textured to generate a single piezoelectric coefficientd33perpendicular to the substrate surface and theAl2O3layers were amorphous at 375 °C. The interfacial sharpness and the film orientation were analyzed by low and high angle x-ray diffraction &thgr;–2&thgr; scanning. High frequency resonance of 10.6 GHz was measured and higher values up to 100 GHz are expected in the multilayer films with periods 320 nm or smaller. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119605

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Based on the results of molecular dynamics simulations, we propose an analytical expression for the velocity distributions of molecules ejected in laser ablation. The Maxwell-Boltzmann distribution on a stream velocity, commonly used to describe the measured velocity distributions, is modified to account for a range of stream velocities in the ejected plume. The proposed distribution function provides a consistent description of the axial and radial velocity distributions. The function has two parameters that are independent of the desorption angle and have clear physical meaning, namely, the temperature of the plume and the maximum stream velocity or velocity of the plume propagation. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119606

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Selected area deposition of diamond films on silicon substrates was successfully achieved using the patterned Pt layer as a nucleation inhibitor in the chemical vapor deposition process. The planar diamond film array thus made possesses good electron field emission properties, that is, emission current density of(Je)Si=150 &mgr;A/cm2(under 23.6 V/&mgr;m) and turn on field of(Eo)Si=10 V/&mgr;m.Precoating a thin Au layer (20 nm) on a Si surface further increased the emission current density to(Je)Au/Si=960 &mgr;A/cm2(under 23.6 V/&mgr;m) with(Eo)Au/Si=10 V/&mgr;m.The effective work functions (&fgr;) estimated by Fowler–Nordheim plots of theI–Vcharacteristics are(&fgr;)Si=0.059 eVand(&fgr;)Au/Si=0.085 eV.The emission properties of both planar diamond film arrays satisfy the requirement for applying as the electron emitters in the flat panel displays. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119607

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.120558

出版商:AIP    

年代:1997

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.120560

出版商:AIP    

年代:1997

数据来源: AIP