摘要:

Radiation dosimetry in the ultraviolet is described using the intrinsic ultraviolet response of a novel thermoluminescent semiconductor‐doped Vycor glass. A linear response to 185 nm light was measured over the range 0.1 to 1000 &mgr;J/cm2. The long wavelength limit of the sensitivity of the glass is ∼290 nm, indicating the utility of the glass as an effective solar blind dosimeter. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114999

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a set of experiments which systematically clarifies the enhancement of photoelectrochemical (PEC) etching due to the mole fraction of aluminum in AlxGa1−xAs. The spatial resolution of gratings etched in Al0.3Ga0.7As is as much as three times greater than the spatial resolution of gratings etched in GaAs, so that the smallest practical grating period is about 0.3 &mgr;m, as compared with about 0.7 &mgr;m using previous techniques. This technique enabled PEC fabrication of first order gratings for waveguide outcouplers. The lower hole mobility of AlxGa1−xAs is proposed as a possible explanation for this grating resolution improvement. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.115000

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A method is presented for direct visualization of electromagnetic microfields. Using a transmission electron microscope equipped with a field‐emission electron gun and two electron biprisms, an object wave and two reference waves are superposed to interfere for producing a new type of interference pattern in which electromagnetic fields are directly observed. Equal‐potential lines of an electric field around a latex particle and magnetic flux lines emerging from a barium ferrite particle have been observed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115001

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Neutron powder diffraction can provide important structural information on hydrogenous compounds which are gases at ambient temperature. For high pressure studies, however, this technique has been seriously limited by the fact that it was impossible (a) to load such gases in large volume devices and (b) to compress them to elevated pressures above some 1 GPa. In this letter we show that, using a previously described pressure cell, a wide range of gaseous samples may be loaded and compressed to ∼10 GPa with standard tungsten carbide anvils. We illustrate the effectiveness of the technique with neutron powder diffraction data recently collected on deuterated ammonia ND3phase IV, where accurate structural data were obtained after a few hours collection time. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115002

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Structural properties of porous silicon were studied with atomic‐force microscopy (AFM) and optical second harmonic generation (SHG). Depending on etching conditions, the SHG response was observed to be either anisotropic, showing C2vsymmetry, or isotropic. This correlated with AFM observations of quasi ordered structures in the first case. The Si etching process was studied byinsituSHG measurements. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115003

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The critical dose for graphitization of diamond as a result of ion implantation induced damage (boron and arsenic) and subsequent thermal annealing is determined by combining secondary ion mass spectroscopy measurements, chemical etching of the graphitized layer, andTRIMsimulations. Li ions are implanted as a deep marker to accurately determine the position of the graphite/diamond interface. The damage density threshold, beyond which graphitization occurs upon annealing, is found to be 1022vacancies/cm3. This value is checked against published data and is shown to be of general nature, independent of ion species or implantation energy. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115004

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In combination with scanning electron microscopy and x‐ray pole‐figure analysis high resolution electron microscope (HREM) observation of the diamond‐silicon cross section in a ⟨001⟩ epitaxially oriented diamond film was carried out to investigate the atomic interfacial microstructure. The films were prepared by microwave plasma chemical vapor deposition using a bias‐enhanced nucleation technique. Due to the multiple fit of diamond and silicon lattices, there is a periodic 3‐to‐2 registry of {111} atom planes of the epitaxial diamond‐silicon interface. Planar defects on diamond {111} planes and interface misfit dislocations are shown for epitaxially oriented and for slightly misoriented diamond crystallites. A cubic silicon carbide ‘‘transition’’ is found to be unnecessary for the epitaxy. The misorientation of the grown crystallites is also studied and found to be probably due to interface imperfection. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115005

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Internal friction measurements have been performed in order to study the Li mobility in Al‐Li alloys. Coherent &dgr;′ precipitation (nonequilibrium diffusion process) promotes a low temperature background increase according to Schoeck’s theory. A stablePzrelaxation has been observed at around 460 K (∼1 Hz). The analysis of the behaviour of this relaxation allows us to identify thePzpeak with the Zener relaxation associated to the stress induced Li‐Li pairs reorientation. The relaxation parameters lead us to determine the activation energy and the diffusion coefficient of Li. Zener relaxation has been observed in Al‐Li alloys. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115006

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A technique utilizing the reflection of x‐rays to determine material density at flat surfaces is described. The effects of sample misalignment limit the accuracy of x‐ray reflectivity as typically practiced. These effects may be properly accounted for by measuring the critical angle for reflection at many different x‐ray wavelengths simultaneously from which an extrapolation of the position of the critical angle at infinite wavelength may be made. This extrapolation has the effect of correcting for sample misalignment. Use of the technique is demonstrated for single‐crystal silicon surfaces and for silica spin‐on‐glass thin films. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115007

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Similarities between the processes that occur during sputtering of monocrystalline Si by reactive O2+primary ions and the interface SiO2/monocrystalline Si by noble gas ions (e.g., by Ar+) have motivated us to utilize the semiempirical model of P. C. Zalm and C. J. Vriezema [Nucl. Instrum. Methods B67, 495 (1992)], modified later by M. Petravic´, B. G. Svensson, and J. S. Williams [Appl. Phys. Lett.62, 278 (1993)] to calculate the decay length &lgr;b, as defined by J. B. Clegg [Surf. Interface Anal.10, 322 (1987)], at the SiO2/Si interface. The measured and calculated results agree remarkably well. Inconsistency observed to be larger than 100% for glancing incidence angles confirms limitations of this model that were admitted already by its authors. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115008

出版商:AIP    

年代:1995

数据来源: AIP