摘要:

Microindentation at room temperature has been studied, by transmission electron microscopy, for GaAlAs and GaInAs with a range of compositions. Both p-type and n-type alloys have been investigated with particular reference to the formation of microtwins. A change of doping from n-type to p-type in GaAlAs results in microtwin formation along perpendicular ⟨110⟩ rosette arms. This is also observed in n-type GaInAs alloys.

ISSN:0950-0839    

DOI:10.1080/09500839108201961

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

L12precipitate shearing processes by (a/3)⟨112⟩ dislocations duringin situstraining of a superalloy in a transmission electron microscope are reported. Information about the core structure of such dislocations is obtained from the way they split when they get out of a precipitate. We conclude that a further dissociation into two identical Shockley partials occurs.

ISSN:0950-0839    

DOI:10.1080/09500839108201962

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Side bands due to purely composition and combined composition-strain modulation in plan-view specimens of a nominally Ge0·5Si0·5(Snm)/Si(25nm) superlattice have been obtained by large-angle convergent-beam electron diffraction. The intensities of the side bands have been calculated from a periodic tension-compression model of the superlattice bilayer using the kinematical theory of electron diffraction. Accurate values of elastic strains in the bilayer and of the Ge content can be obtained in this way.

ISSN:0950-0839    

DOI:10.1080/09500839108201963

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A stable decagonal quasicrystal phase in the Al–Mn–Pd system is described. Its composition is Al70·5Mn16·5Pd13, as determined by X-ray microanalysis attached to a scanning electron microscope. The temperature range of stability has been found to be around 800°C by investigation of differently annealed specimens in a transmission electron microscope. An icosahedral quasicrystal phase with composition Al70·5Mn8·5Pd21and a face-centred icosahedral quasilattice has also been found, partly in coexistence with the new decagonal phase. The icosahedral phase is also stable at temperatures around 800°C. The Al–Mn–Pd system is the first system in which stable decagonal quasicrystals as well as stable icosahedral quasicrystals occur.

ISSN:0950-0839    

DOI:10.1080/09500839108201964

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The photodoping kinetics of silver into glassy As–S films, induced by pulsed excitation, has been studied. The electrical resistance of the metallic silver layer changes instantaneously after excitation with a time constant of about 50μs, which is nearly the same as the response time of photoconduction in the silver-doped sample. These observations suggest that the silver movement in the photodoping process is triggered by the silver penetration into the photodoped region, which is caused by an increase in the conductivity in the doped region.

ISSN:0950-0839    

DOI:10.1080/09500839108201965

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The effect of doping on the steady-state photoconductivity σpof hydrogenated amorphous silicon (a-Si:H) down to temperatures of 4·2 K has been studied. Phosphorus doping up to 10−2PH3/SiH4does not essentially change σp/eG, the photoconductivity normalized by the photocharge generation rateeGeither at lowTwhere σp/eGis constant, or between 30K <T< 50K where it rises withT.Boron doping on the other hand causes σp/eGat low T to decrease significantly and to rise withTat a higher temperature. This effect of boron doping is not related to the defect density or to the sign of the charge carriers. We tentatively attribute this effect to a heterogeneous morphology that is associated with boron doping.

ISSN:0950-0839    

DOI:10.1080/09500839108201966

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor