摘要:

Homogeneous crystals of Bi‐Sb solid solutions are difficult to grow, but are important for the basic understanding of the electron transport properties and band structure of these materials. The problems arise from (1) the low melting temperature (approximately 300°C) which makes it difficult to achieve a large thermal gradient at the crystal growing interface; (2) the small liquid diffusion coefficient which was estimated to be between 2 and 3×10−5cm2/sec at 300°C; and (3) a segregation coefficient so large (5–10) as to favor growth of undesirable cellular substructure. Under existing theories of crystal growth, the conditions necessary for producing crystals with Sb compositions from 5% to 14% free of macro‐ and micro‐inhomogeneity are described. A zone‐melting technique was used to grow the crystals with temperature gradients in the molten zone about 60°C/cm and growth rates between 1.6 and 0.4 mm/h. The degree of homogeneity was determined by etching studies, chemical analysis, and electron beam microprobing. Preliminary electrical measurements show considerable difference from previous measurements, particularly for the higher Sb contents.

ISSN:0021-8979    

DOI:10.1063/1.1713776

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Diffuse streaks in the electron diffraction patterns of single‐crystal white tin films appear to be associated with nearby reflections, whether they are allowed or forbidden by the structure factor. Zero‐order streaks, also observed, as well as the forbidden reflections and their accompanying streaks, are interpreted as resulting from multiple diffraction events. The disappearance of the streaks in x‐ray patterns when the sample is cooled to −155°C suggests that they arise from an interaction between the incident radiation and very short wavelength elastic waves having highly anisotropic propagation.

ISSN:0021-8979    

DOI:10.1063/1.1713777

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Stereo pairs of x‐ray projection topographs have been used to elucidate the configuration of dislocations in a silicon bar lightly deformed at about 900°C. Dislocation reactions and interactions associated with a ten‐turn Frank‐Read spiral are described.

ISSN:0021-8979    

DOI:10.1063/1.1713778

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Precise relationships between the diffusion coefficientDand the zinc concentrationCare obtained from isoconcentration diffusion experiments performed at 900°C for zinc in GaAs and at 1000°C for zinc in GaP. It is found thatDvaries withCfrom a slightly less than cubic to a somewhat less than square dependence over the concentration range 1018to 1020cm−3.Possible mechanisms that result in concentration‐dependent diffusion are discussed. Under the conditions given above, it is concluded that diffusion occurs by an interstitial‐substitutional mechanism with the interstitial mode being dominant. The charge states of the various species involved in the diffusion are believed to be: (1) interstitial zinc atoms are doubly ionized donors; (2) substitutional zinc atoms are either neutral or singly ionized acceptors; and (3) gallium vacancies are neutral. A theoretical expression forDversusC, derived under these assumptions, fits the isoconcentration diffusion data over wide ranges ofDandCthrough the use of only one adjustable parameter.

ISSN:0021-8979    

DOI:10.1063/1.1713779

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

A metallographic investigation has been made of the nature and depth of the damaged layers in abraded {111} surfaces of InSb. It is shown that the damage consists of cracks which are associated with crack‐like dislocation arrays of the type known to exist in abraded germanium and silicon surfaces. However, in InSb the damaged layer also contains glide dislocations and features which are thought to correspond to twins, both of which are absent in the elemental semiconductors. Contrary to previous reports by other workers, the depth of damage, taken as the depth of the deepest cracks, is found to be the same in surfaces terminating with In atoms and in those terminating in Sb atoms. In both cases, the glide dislocations and the twins extend to approximately half the depth of the deepest cracks.

ISSN:0021-8979    

DOI:10.1063/1.1713780

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

The concentration dependence of the diffusion coefficient of Zn in GaAs has been measured under excess arsenic vapor pressure at 850°C. The diffusion coefficient varied under these conditions only from 10−11to about 10−10cm2/sec as the zinc concentration increased from 1017to 1020zinc atoms/cm3. These results are compared with diffusion coefficients found in the absence of excess arsenic by the authors and other workers. The observed difference can be explained by means of an interstitial‐substitutional equilibrium. The excess arsenic increases the substitutional component of the diffusion and suppresses the interstitial component. These results are in good agreement with the model first suggested by Longini. The activation energy of the substitutional diffusion coefficient is found to be about 2.8 eV.

ISSN:0021-8979    

DOI:10.1063/1.1713781

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Formulas have been developed for the direct gamma‐radiation (photopeak) response of a simple slit‐collimated crystal detector as a function of position and gamma‐ray energy of point sources that are embedded in isotropic absorbing matrices. Apart from optical considerations, the effects of edge penetration, crystal absorption, source matrix absorption, and for higher energies, penetration of the collimator wall have been taken into account. A comparison between measured and calculated response curves has been made.

ISSN:0021-8979    

DOI:10.1063/1.1713782

出版商:AIP    

年代:1964

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1713785

出版商:AIP    

年代:1964

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1713786

出版商:AIP    

年代:1964

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.1713787

出版商:AIP    

年代:1964

数据来源: AIP