摘要:

The application for surface sensitive analytic techniques to the study of grain boundary diffusion in thin films is described. Two common experimental configurations, sputter profiling and permeation analysis, are described, as are solutions for data reduction. Analytic solutions are difficult to use, even with simplifying assumptions. Rather, a versatile numerical method for data reduction, the method of lines, is used to analyze concentration profiles and surface accumulation concentrations. Both analytic and numerical calculations are compared to data for chromium diffusing in gold and the grain boundary half‐width times diffusion coefficient (cm3/sec) is shown to be 8.6 ×10−11 exp(−25000/RT).

ISSN:0021-8979    

DOI:10.1063/1.323259

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Two electron traps—A2 and A3—produced inn‐type silicon by 1.5‐MeV‐electron irradiation are characterized by deep level transient spectroscopy. Activation energies of trapped majority carriers and capture cross sections for majority carriers at these levels are reported. From their production rates and annealing behaviors, they have been identified as different charge states of the same defect. Detailed annealing studies show that their annealing kinetics is first order with an activation energy of 1.47 eV. It is suggested that the defect is the divacancy and that dissociation is the likely process for its removal in these devices.

ISSN:0021-8979    

DOI:10.1063/1.323260

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The hydrodynamic effects of ultrasound in the nematic liquid crystal MBBA are studied. The conditions for the formation of rolls or disclinations are given. The roll patterns are then examined and found to be produced at very low ultrasound intensities.

ISSN:0021-8979    

DOI:10.1063/1.323261

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The role of Ag+‐interstitial and Ag+‐vacancy transport across silver halide surfaces is important for both ionically blocking and nonblocking interfaces. One technique to evaluate the nature of a blocking silver halide surface is to measure the alternating‐current dielectric loss of silver halide microcrystals in contact with an insulating dry‐gelatin phase. From the results of these measurements, the availability of the potential‐determining Ag+interstitial was determined as a function of silver halide type, crystal size and morphology, and the addition of divalent cations within the silver halide phase and adsorbed at the surface. The results on small crystals (0.2 &mgr;m) and, analogously, for very thin films, where the Debye length is comparable to the linear thickness, indicated that the Ag+‐interstitial concentration is a critical function of the surface properties of the silver halide. Consequently, the transport of ionic carriers across the silver halide is not only dependent on bulk solid‐state properties, but also on the nature of the surface and the ionic space‐charge layer just below the surface.

ISSN:0021-8979    

DOI:10.1063/1.323262

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Measurements of the dielectric constant, polarization, zero‐field specific heat, and field‐dependent specific heat of polycrystalline Pb2Nb2O7at low temperatures are reported. No evidence for a phase transition at 15 K was found, contrary to previous suggestions of an antiferroelectric transition at 15 K based on dielectric data. The peak in the dielectric constant appears to be due to relaxation phenomena.

ISSN:0021-8979    

DOI:10.1063/1.323263

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Diffusion through grain boundaries in thin films is analyzed using a model with a single high‐diffusivity plane perpendicular to the film. One surface of the film is maintained at unit concentration of the diffusing species, and a zero‐flux boundary condition is applied at the other surface. It is shown that the region of the film where the diffusion species is supplied primarily by grain‐boundary diffusion has a far smaller concentration gradient than that predicted by a similar model with semi‐infinite geometry. As a result, calculations of grain‐boundary diffusion coefficients in thin films based on the semi‐infinite model may be in error by several orders of magnitude. Two methods for the analysis of thin‐film diffusion data are described that should provide accurate values of grain‐boundary diffusion coefficients.

ISSN:0021-8979    

DOI:10.1063/1.323264

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Auger studies of silver, copper, gold, and nickel nuclei evaporated onto carbon films show that a large fraction of the metal diffuses into the film. Subsequent exposure of the metal nuclei on the surface to room atmosphere for one week results in severe contamination by S. Relative changes in the Auger peak positions for Au evaporated on carbon have been recorded as a function of coverage. The studies indicate that the changes are complete at 2.5×1015atoms/cm2. Carbide formation has been observed in the case of evaporated Fe and Al on carbon, but not for any of the other metals considered here.

ISSN:0021-8979    

DOI:10.1063/1.323213

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Low‐temperature (75–150 °C) diffusion of copper through gold is studied with Auger electron spectroscopy. Grain‐boundary or pipe diffusion measurements and calculations are discussed with boundary‐value‐problem assumptions. Electroplated cobalt‐hardened gold on electroplated copper printed‐wiring‐board fingers is used. In addition, contact‐resistance data is presented for different heating times and temperatures and a plot of CR values versus amount of surface film is shown. Chlorine, which evolves from the board material upon heating, reacts with copper which has diffused to the surface. This reaction provides a much better sink for the copper than oxidation. Diffusion coefficients are estimated which are several orders of magnitude larger than those previously reported for the Au‐Cu system and reasons are discussed. Because of the chlorine emanating from the board, data from accelerated tests, in which the printed wiring board is also heated to elevated temperatures, may give erroneous predictions when extrapolated using an Arrhenius plot. Results demonstrate that diffusion via the defect structure isnotthe rate‐controlling step in the accumulation of copper and/or copper compounds on the gold surface when exposed to normal atmospheres. The surface accumulation is limited by the growth kinetics of the surface film.

ISSN:0021-8979    

DOI:10.1063/1.323265

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Transmission electron microscopy has been used to characterize the crystallography of structural defects observed in a Czochralski‐grown silicon crystal after a two‐step annealing treatment. The defect population is complex and consists of precipitates, perfect‐dislocation loops, single and double stacking‐fault loops, microprecipitate colonies on stacking faults, and imperfect/perfect dislocation‐loop pairs. Extensive diffraction‐contrast experiments have been carried out in order to evaluate the nature of these defects. The results indicated that all the observed defects place the surrounding silicon matrix in a comprehensive state (i.e., they are of the so‐called interstitial type). It is clear from the electron‐microscopy observations that perfect‐dislocation loops are generated at the precipitate/matrix interface by prismatic punching. However, the structure and elemental nature of the precipitates is unknown. The role that oxygen may play in the formation of precipitates, perfect‐dislocation loops, and the mechanisms of formation of stacking faults with their associated microprecipitates is discussed. Additional experimental work in the earlier stages of defect formation is required to clarify this picture.

ISSN:0021-8979    

DOI:10.1063/1.323241

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The feasibility of performing simultaneous RHEED–mass‐spectrometric‐molecular‐beam experiments is demonstrated with a study of the nucleation of Cd on a contaminated Ge(111) surface. The crossed‐beam experimental geometry and the scheme for determining absolute adatom density is described. The nucleation mechanism is found to have the appearance of a two‐dimensional gas‐solid phase transformation. The critical adatom density was found to be dependent on the level of contamination. The onset of clustering was found to correlate well with the MSMB spectra and clusters approaching critical dimensions were observed.

ISSN:0021-8979    

DOI:10.1063/1.323242

出版商:AIP    

年代:1976

数据来源: AIP