ISSN:0022-5355    

DOI:10.1116/1.1316359

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

The effect of alloying uranium with 7.5-wt% Nb and 2.5-wt% Zr (“Mulberry” alloy) on the initial oxidation kinetics (surface oxide thicknesses up to 2000 Å) in air containing water vapor was investigated using an ellipsometer high vacuum system. The uranium alloy samples were oxidized in dry air(<5 ppm H2O)and air containing water vapor(15 000 ppm H2O)at a pressure of 650 Torr in a temperature range of 22 °–200 °C. The results differed from the oxidation of uranium in that the oxidation of this uranium alloy was not enhanced by water vapor under the conditions studied. The oxidation of unalloyed uranium in air is accelerated by water vapor. The oxidation followed a parabolic-rate law, indicating a diffusion-controlled mechanism. An Arrhenius plot of the parabolic reaction rates as a function of the reciprocal temperature revealed a difference in the activation energy of the low-temperature (22 °–100 °C) and high-temperature (100 °–200 °C) oxidation.

ISSN:0022-5355    

DOI:10.1116/1.1316361

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1316362

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

The phyllosilicate minerals are ideal materials for a study of cohesion between molecularly smooth surfaces. The lamellar structure of these materials allows the surface energy to be measured experimentally by a cleavage process. The surface energy of synthetic phlogopite has been measured in vacuum, air, oxygen, ammonia, carbon monoxide, and water. No reduction in the surface energy was observed in an oxygen environment. However, water vapor, air, carbon monoxide, and ammonia environments reduced the surface energy of phlogopite. Results of this study support a model which explains how selected environments may result in a reduction in the observed surface energy of silicate minerals.

ISSN:0022-5355    

DOI:10.1116/1.1316363

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

The techniques currently used for the study of solid surfaces will be reviewed and discussed. Emphasis will be placed on the comparison of the capabilities and limitations of the various techniques. In addition, the relationships between the various kinds of measurements will be discussed. Some areas of potential development will also be presented.

ISSN:0022-5355    

DOI:10.1116/1.1316364

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1316365

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

The use of Auger electron spectroscopy (AES) as a tool for the study of band structure or Auger processes in solid has been limited by the lack of resolution resulting from the excitation and measurement methods used in AES. In addition to these instrument broadening effects, it is found that discrete, inelastic interactions of Auger electrons in solid can contribute a structured, low-energy tail which extends several times the main bandwidth. By using the energy-loss and resolution information contained in the nearly elastically backscattered electron distribution in a deconvolution technique, it was found that the effects of instrument broadening and inelastic interactions in the observed Auger electron energy distribution could be significantly reduced, thus yielding higher resolution Auger spectra. Deconvolved spectra were obtained from In and CdS as well as from oxygen adsorbed on several substrates.

ISSN:0022-5355    

DOI:10.1116/1.1316366

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

A simple, nondispersive spectrometer has been used to study the binding energies of core electrons at solid surfaces. The spectrometer consists of a photomultiplier which measures the soft x-ray fluorescence of an electron-bombarded surface. The derivative of the multiplier current as a function of target potential rises abruptly at the threshold energies at which core electrons can be excited to unoccupied states. This produces a comparatively simple spectrum for metals with each level being represented by a sharp peak, followed by an abrupt step. For nonmetals, however, the spectrum of a single level can consist of a series of sharp peaks spread over as much as 30 eV.

ISSN:0022-5355    

DOI:10.1116/1.1316367

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

In the absence of surface impurities detectable by Auger electron spectroscopy, several semiconductor surfaces studied showed surface rearrangement using low-energy electron diffraction. The structures observed areSi{111}2×1and7×7,Ge{111}2×1and2×8,GaAs{111}2×2,InSb{111}2×2, InSb {111¯}3×3, andInSb{112}1×1. The Auger electron spectra for some of these surfaces are also presented.

ISSN:0022-5355    

DOI:10.1116/1.1316368

出版商:American Vacuum Society    

年代:1971

数据来源: AIP

摘要:

In situLEED studies of the homoepitaxial growth of Si(111) films by uhv sublimation, indicate a strong correlation between the type of surface structure generated and the metallic impurity content of the silicon substrates as estimated from minority carrier lifetimes. The development of the familiarSi(4111)−7×7structure is favored by the presence of lifetime-killing impurities in the substrate. Experiments where Fe is introduced on high lifetime substrates prior to annealing and film growth, suggest that this impurity species plays a role in the generation of the7×7surface structure. Electron microscopy reveals that homoepitaxial Si(111) layers are generally faulted, the number density of which increases progressively as the growth temperature is lowered. Films deposited on high-lifetime silicon contain substantially fewer stacking faults than those grown on low-lifetime substrates. These results suggest that the faults originate at microprecipitates at the substrate surface consisting of fast-diffusing, low-solubility impurity species.

ISSN:0022-5355    

DOI:10.1116/1.1316369

出版商:American Vacuum Society    

年代:1971

数据来源: AIP