Molecular beam epitaxy of InAs on micro- and
nano-scale patterned GaAs(001) substrates was studied. An InAs epilayer grown
on the micro-scale patterned substrate exhibits islands with {1 1 3}-type
facets, and is similar to that grown on the flat (unpatterned) substrate. In
contrast, the preferred growth of InAs on the nano-scale patterned substrate is
in the \langle 001\rangle direction and
exhibits islands with {1 1 0}-type facets. The thickness of the dense
dislocation networks at the interface due to strain relaxation is reduced by
the micro-scale pattern in comparison with the flat substrate, while for growth
on the nano-scale patterned substrate, the strain relaxes via the formation of
stacking faults more than dislocations. X-ray diffraction reveals that the
strains in the 300 nm InAs epilayers are nearly fully relaxed, and the patterns
tend to decrease the lattice constants of the epilayer, implying mass transport
of Ga atoms into the epilayer from the GaAs substrates.
Source:IOPscience
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