摘要:

We have observed precise geometrical correlation between ``dark‐line''‐type defects characteristic of the rapid degradation mode of (optically pumped) AlGaAs DH laser material with etch pit features in the vicinity of the GaAs/p‐AlxGa1−xAs heteroboundary. The patterns observed strongly suggest that the degradation is associated with creation or possibly decoration of dislocation linesinclined tothe {100} junction plane, and that the commonly observed ⟨100⟩ orientation of the dark lines is due to statistical aggregation of such inclined lines.

ISSN:0021-8979    

DOI:10.1063/1.1663271

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The solution strengthening of sodium and potassium halide crystals by dissolved alkaline earth atoms is accounted for quantitatively. Strengthening is associated with the change in electrostatic energy that occurs when a divalent ion‐vacancy complex is sheared by a dislocation that passes through it. The model yields a hardening coefficient of 11 × 109dyn/cm2compared with the experimental value of 9.2 × 109dyn/cm2.

ISSN:0021-8979    

DOI:10.1063/1.1663272

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

New data are given for the thermal and electrical conductivities and thermoelectric power of Pb from 260 to 550 K. Comparison of these data with literature values suggests that, contrary to some reports, there are no anomalous purity effects in the thermal conductivity at high temperatures and that some of the recently recommended values for this parameter may be some 2% too high.

ISSN:0021-8979    

DOI:10.1063/1.1663273

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The dose dependence of the lattice parameter change for neutron‐irradiated copper has been measured in the range (1.0–10.8)×1018neutrons/cm2. The lattice parameter changes were measured directly by using a multiply reflecting monochromator, and an analysis of the effects of misalignment in the geometry has been given. The lattice parameter changes, showing a pronounced saturation with dose, were analyzed using second‐order elasticity theory applied to the case of dislocation loops.

ISSN:0021-8979    

DOI:10.1063/1.1663274

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The stress distributions at and near the surface due to a single edge dislocation and to a group of uniformly spaced edge dislocations on an oblique glide plane have been calculated. For the evaluation of the stress an Airy stress function, previously derived, was used after a change in sign of one of the terms. The shear stress at the surface develops an increasingly sharp maximum at the acute angle between the surface and the glide plane as the single dislocation or the leading dislocation of the array approaches the trace of the glide plane. This stress is superimposed additively on the applied stress. Over the region of the stress maximum the probability for the generation of dislocations with a Burgers vector of opposite sign on parallel glide planes is increased compared with that for their generation elsewhere at the same surface. This leads to a possible explanation of the frequent occurrence of clusters of activated glide planes in close‐spaced pairs.

ISSN:0021-8979    

DOI:10.1063/1.1663275

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

When single crystals of Cu‐7.5 at.% Al alloys with the [331] {1¯10} {1¯1¯6} orientation are deformed in tension, narrow slip bands are introduced in which only one or the other of the two equivalent {1¯1¯1} ⟨101⟩ and {1¯1¯1} ⟨011⟩ glide systems is activated. Along the gauge length, bands due to the activation of the two glide systems appear in equal numbers. To facilitate the interpretation of these results a model for the relaxation process has been set up and analyzed. The stress distributions at and near the surface due to a single 60° dislocation and to a group of uniformly spaced 60° dislocations on an oblique (1¯1¯1) glide plane have been calculated. The results lead to an interpretation of the experimental observations and suggest that a stress difference of 0.038–0.083 kg mm−2in a resultant resolved shear stress of 1.34–1.54 kg mm−2is sufficient to cause preferential activation of one of the two equivalent glide systems. They provide a clear and equivocal demonstration of the role of internal stresses in dislocation generation processes in single crystals of &agr;‐phase Cu&sngbnd;Al alloys with this orientation.

ISSN:0021-8979    

DOI:10.1063/1.1663276

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

GaAs epitaxial growth by the open‐tube AsCl3&sngbnd;Ga&sngbnd;N2vapor‐transport technique was thoroughly examined as to its growth conditions, with some discussion on an optimum condition supplemented. The results of Hall, impurity profile, and photoluminescence studies for both the epitaxial layers grown in the nitrogen carrier gas and in the hydrogen carrier gas were described for the sake of comparison. A number of experiments successfully revealed a residual impurity in an undoped epitaxial layer. It was found that the present method exceeds the conventional one in many respects when preparing high‐purity uniform epitaxial layers.

ISSN:0021-8979    

DOI:10.1063/1.1663277

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The usefulness of ion‐induced x‐ray yields to detect low‐Zimpurity atoms at low concentration in medium‐Ztargets and to locate their lattice sites in single crystals is established in this and the paper that follows. In paper I we describe the technique used with specific reference to phosphorus and sulfur implants in germanium crystals. Particular attention was given to the origin of the different components that constitute the backgrounds in the x‐ray energy spectrum. Peak‐to‐background ratios for these two impurity signals were then determined for H and He ions in the energy region from 0.5 to 2.0 MeV. Some results for N and Ar ions were also obtained. A beam of 0.5‐MeV H+gave optimum conditions for foreign atom location studies.

ISSN:0021-8979    

DOI:10.1063/1.1663278

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

In the preceding paper, Paper I, we described an analytical technique, based on ion‐induced x‐ray yields, for detecting low‐Z impurities in medium‐Z targets. In this paper, Paper II, we report the application of this method to the lattice location of impurity atoms. Two systems have been examined to test the method, viz., P and S implants in Ge single crystals. The channeling effect was applied to the phosphorus and sulfurKx‐ray yields excited by 0.5‐MeV protons. Some 93% of implanted31P (0.7 × 1015atoms cm−2, room‐temperature implant, 450°C anneal), were found to occupy substitutional sites; the fraction dropped to [inverted lazy s] 63% for an implant dose of 2.7 × 1015atoms cm−2. Channeling effect results in ⟨110⟩, ⟨111⟩, and ⟨100⟩ directions for Ge(S), implanted at room temperature and annealed at 450°C, prescribe a preferred off‐lattice (> 0.3 Å) site for the sulfur, necessarily different from the regular tetrahedral or hexagonal interstitial sites. For hot (220°C) implantation conditions, poorer crystal annealing and weaker channeling effects were observed.

ISSN:0021-8979    

DOI:10.1063/1.1663279

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Low‐dislocation‐density copper crystals have been neutron irradiated at low temperatures(T≲50∘K)and transferred to an x‐ray diffractometer at temperatures less than 25°K. Simultaneous measurements of anomalously diffracted x‐ray intensities, the lattice parameter, and the electrical resistivity were made at 4.2°K after successively higher annealing temperatures in an isochronal annealing program; x‐ray measurements were made on approximately 1 × 1 × 0.15‐cm samples, and resistivity measurements were made on wire specimens. The anomalous x‐ray absorption, which is most sentitive to clustering of defects, showed a steady increase beginning at the end of stage I and continuing to about 225°K, the end of stage II. During stage III a small decrease in the absorption was observed. A rather pronounced increase in the absorption occurred in stage IV at about 375°K. The ``clustering peaks'' at 225 and 375°K have been compared with electrical resistivity data, and the results are interpreted in terms of existing annealing models.

ISSN:0021-8979    

DOI:10.1063/1.1663280

出版商:AIP    

年代:1974

数据来源: AIP