摘要:

The field ion microscope is demonstrated to be a useful tool for studying the motion of grain boundaries in metals. Heating is accomplished by passing a current through a high‐resistance specimen support loop. An example is shown of migration of a grain boundary in tungsten. The radius of curvature at the specimen apex was approximately 12 nm and displacements in the boundary as small as 1 nm are observed.

ISSN:0003-6951    

DOI:10.1063/1.90303

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The surface acoustic wave properties of berlinite have been measured for thex‐axis boule 92.75° cut. This cut was found to be temperature compensated at 32 °C. The velocity and coupling coefficientk2were found to be 2747 m/sec and 0.003, respectively. The velocity and temperature coefficient of delay are in reasonable agreement with theory, while the value ofk2is lower than the theoretical value.

ISSN:0003-6951    

DOI:10.1063/1.90279

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The feasibility of line acoustic wave delay lines at high frequencies using single‐phase transducers is demonstrated. Experimental results are presented for a 219.5‐MHz device and it is expected that much higher frequency devices are possible.

ISSN:0003-6951    

DOI:10.1063/1.90304

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A crucial problem in pulsed linear ion accelerators is the time‐dependent space‐charge neutralization of the ion beam by electrons from the walls. Analytic estimates and numerical simulation are used to discuss this problem, and it is found that in the presence of a magnetic field transverse (but not normal) to the ion flow, there is nearly complete neutralization on the scale of the ion beam rise time.

ISSN:0003-6951    

DOI:10.1063/1.90305

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A bandwidth‐limited 15‐psec laser pulse is used to induce multiphoton photoelectric emission from a gold metal cathode. The wavelength is tuned between 10 580 and 10 620 A˚ to investigate the transition from a four‐photon to a five‐photon photocurrentjfrom a gold surface. This transition gives rise to a new effect marked by a dramatic change of the slopen=∂ logj/∂ logI, whereIis the laser intensity.

ISSN:0003-6951    

DOI:10.1063/1.90306

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Differential resistivity and Hall effect measurements and secondary ion mass spectrometry (SIMS) are used to study the annealing behavior of GaAs doped with high Be concentrations during growth by molecular beam epitaxy (MBE). The diffusion coefficient of MBE‐grown Be in GaAs is determined to be (0.5–1) ×10−13cm2/sec at 900 °C, a value which is two orders of magnitude lower than that for implanted Be of equal concentration [(2–3) ×1019cm−3]. The concentration dependence of the diffusion of MBE‐grown Be in GaAs is also observed to be substantially less than that for implanted Be. The implantation of He in Be‐doped MBE layers to create lattice damage does not significantly affect the Be diffusion in a subsequent anneal.

ISSN:0003-6951    

DOI:10.1063/1.90307

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We demonstrate that a single short pulse of laser irradiation of appropriate energy is capable of recrystallizing in open air an amorphous Si layer deposited on a (100) single‐crystal substrate into an epitaxial layer. The laser pulse annealing technique is shown to overcome the interfacial oxide obstacle which usually leads to polycrystalline formation in normal thermal annealing.

ISSN:0003-6951    

DOI:10.1063/1.90280

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Orientation of molecular dipoles in poly(vinylidene fluoride) (PVF2) films under electric field has been measured by ir spectroscopy using ir transparent indium‐tin‐oxide electrodes. Significant changes in ir transmission with electric field have been observed at 512 and 446 cm−1, which demonstrate that crystalline dipoles in &bgr;‐phase PVF2orient along the electric field. As the field is cycled between positive and negative values, the dipole orientation exhibits a hysteresislike behavior, demonstrating that the polarization of &bgr;‐phase PVF2and its switching result directly from the orientation of crystalline dipoles. Time response of dipole orientation shows that the total orientation consists of an instantaneous part and a slowly developing part. Only the latter seems to contribute to the remnant polarization and its switching.

ISSN:0003-6951    

DOI:10.1063/1.90281

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We examine how the thermal‐pulse technique for determining spatial charge distribution in charged polymer foils is affected by inaccuracies of the measuring process. A theoretical model is developed for thermal equalization processes which is in agreement with the measured temperature transients. Using this model, we show by computer simulation that even for a measurement inaccuracy of less than 1% the obtainable information consists of only the first moment of the charge distribution and the first few Fourier coefficients.

ISSN:0003-6951    

DOI:10.1063/1.90282

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The time evolution of temperature and melting in amorphous silicon layers laser irradiated was calculated numerically. Experiments were performed in Si crystals implanted with 400‐keV As to a dose of 5×1015/cm2and illuminated with 50‐ns‐durationQ‐switched ruby laser pulse in the energy range 1.0–3.0 J/cm2. Comparison between experimental and calculated results allows a quantitative understanding of the amorphous–to–single‐crystal transition. A good agreement was found between the experimental As profiles after laser irradiation and those calculated with a diffusion coefficient of 10−4cm2/s for As in liquid silicon.

ISSN:0003-6951    

DOI:10.1063/1.90283

出版商:AIP    

年代:1978

数据来源: AIP