摘要:

New experimental measurements of the temperature dependence of theR′fluorescence of ruby (77°–450°K) have disclosed features not previously observed. Direct phonon transitions to nearby levels contribute less and indirect Raman processes contribute more to theR3′ linewidth than had previously been reported. Direct phonon relaxation from theR1′ andR2′ levels to the2Elevel contributes appreciably to linewidth of their fluorescence to the ground state.

ISSN:0021-8979    

DOI:10.1063/1.1658521

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The dependence of the equilibrium configurations of a thin single‐crystalline epitaxial film, on the strengths of substrate‐overgrowth and overgrowth‐overgrowth bonds and the interfacial misfit is calculated neglecting substrate deformations. Previous analyses of the system were based on a one‐dimensional model, allowing for misfit, i.e., differing lattice parameters, in one interfacial direction only. The results of these analyses show (i) that interfacial mismatch is accommodated by a parallel sequence of misfit dislocations, (ii) that the mismatch decreases when appropriate overall lateral strains are introduced, (iii) that in stable and metastable film configurations both dislocations and overall strains are present, and (iv) that there exist limiting misfits 2/&pgr;l0and 1/l0, respectively, below which the stable and metastable states are pseudomorphic; the film is homogeneously strained to coherency, i.e., exact fit, with the substrate. The transition to the noncoherent state is critical, the change in average lattice parameter being discontinuous. The parameterl0depends on the various bonding strengths and yields, in an average case, the values 2/&pgr;l0=9% and 1/l0=14%. The present analysis allows for misfits along two interfacial directions, which may differ from each other and which could be accommodated by a cross grid of dislocations. Qualitatively, the results have many similarities in common with the one‐dimensional case. Quantitatively, most of the results are significantly different, reducing for example, the forementioned limiting misfits by approximately 25%. Furthermore, the transition to noncoherency is not critical and the metastable configurations are probably absent for an island with a curved boundary. Most of the differences are due to the Poisson phenomenon. Some speculations, which deal with refinements of the calculations as to overgrowth shape, size, thickness, and substrate interaction potential are presented.

ISSN:0021-8979    

DOI:10.1063/1.1658522

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The strain dependence of the resistance of thin epitaxial films of silver on mica has been measured for film thicknesses between 300 and 1400 Å, in the temperature range 200°–350°K. Analysis of the data includes geometrical and strain corrections, and considers the possible deviation from bulk of both the mechanical and electrical properties of the films. The films show a strain dependence of the resistivity equal to that of bulk silver, with deviations in individual films up to 30%. The effect is temperature independent, and shows no size effect. It is too small to account for the observed temperature variation of the film resistivities, which is smaller than in bulk, on the basis of strain due to the mismatch of thermal expansion of films and substrate.

ISSN:0021-8979    

DOI:10.1063/1.1658523

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Thin films of Ag and Au were deposited on vacuum‐cleaved alkali halides in ultrahigh vacuum with and without controlled‐chlorine exposures. Chlorine exposures were made (1) prior to deposition, (2) continuously during deposition, or (3) with various delay times after the start of deposition. The film structure and orientation was studied by conventional electron diffraction and electron microscopy. Results show that chlorine induces nearly perfect epitaxy of Ag and Au on NaCl and enhances epitaxy of Ag and Au on KCl and Kbr under deposition conditions that otherwise would produce polycrystalline films. For example, epitaxy of Au on NaCl is obtained at room temperature in a partial pressure of ∼5×10−7Torr Cl2. Possible mechanisms responsible for the influence of Cl2on the orientation of Ag and Au are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1658524

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Magnetic oxide platelets, useful for memory and logic circuits, are presently prepared by diamond abrasive polishing techniques. Processed platelets, however, usually contain thin damage layers and microscopic scratches resulting in increased domain wall coercivity. Platelets less than 1 mil in thickness and of desirable flatness are difficult to prepare using these techniques. Ion milling has been successfully used to rapidly remove abrasive and polishing induced defects and at the same time produce flat surfaces of much less than 1 mil in thickness. The measured removal rate was 0.5 &mgr;/h/side; however 500‐&mgr;/h/side rates are attainable. Final platelets are scratch free, flat, and highly reflecting, having lower domain wall coercivity than diamond polished plates. No change in mobility was observed following ion milling. The process is adaptable to large areas and a wide variety of related applications.

ISSN:0021-8979    

DOI:10.1063/1.1658525

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The ionization rates of (AlxGa1−x) As have been measured as a function of the Al content and the results are presented here. Values of bothAandbare found to increase with Al content. It is also found that for low values of Al content, the ionization rates of (AlxGa1−x) As are consistent with Baraff's theory.

ISSN:0021-8979    

DOI:10.1063/1.1658526

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1658527

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1658528

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1658529

出版商:AIP    

年代:1970

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1658530

出版商:AIP    

年代:1970

数据来源: AIP