81 research outputs found
Laser-induced optical changes in amorphous multilayers
It is shown that the well-known blue-shift of the fundamental absorption edge
in as-deposited compositionally modulated amorphous Si/Ge and As6Se94/Se80Te20
multilayers (with periods of 4-8 nm) is further enhanced due to the thermal or
laser-induced intermixing of adjacent layers. The laser-induced intermixing
process, as supported by experiments and model calculations, can be attributed
to both the local heating and photo-effects in As6Se94/Se80Te20 multilayers,
while only the thermal effects were observed for Si/Ge multilayers. Structural
transformations, based on this enhanced interdiffusion, provides good
capability for spatially patterning optoelectronic devices and digital
information recording
Influence of surface roughness on interdiffusion processes in InGaP/Ge heteroepitaxial thin films
Kirkendall Effect on the Nanoscale
Kirkendall effect has been studied experimentally as well as theoretically for decades already.
There are theoretical indications, that the Kirkendall effect must operate from the beginning
of the diffusion process but there are practically no measurements on this short time and
length scale. For that reason, diffusion on the nanometer scale was investigated
experimentally in different binary systems in thin film geometry. We followed the diffusion
process as well as the Kirkendall effect by different methods (TEM, SNMS and synchrotron
X-ray waveguide technique). Investigations were performed in systems with complete
solubility (Bi-Sb, Cu-Ni, Bi-Sb) as well as in systems forming intermetallic phase (Fe-Sb, Fe-
Pd). It was found that with these methods the Kirkendall shift can be well followed on the
nano-scale. In Fe-Sb system even the bifurcation of the Kirkendall plane was observed
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