P301
Interface effects on the heteroepitaxy
Z.P.Wu et al.
Japan Atomic Research Institute
Thin films deposited on different sapphire substrates have been investigated by XRD, x-ray pole figure
and RBS/Channeling measurements. The results show that films grow epitaxially and exhibit strong substrate
dependence, i.e., three dimensional orientations on (0001) plane, but under any condition, only two
dimensional orientations on (1120) and (0112) planes. Channeling can be detected only in the film grown on
(0001) sapphire with cmin value of 8%. Based on the interface structural analysis and the calculation of
the mismatch, the relationship of film orientation to the symmetry and morphology of substrate surface has
been studied and the heteroepitaxial process can be described as two steps, the one is surface symmetry
determined oriented growth, and the other is in-plane oriented growth dominated by the minimization of
lattice mismatch. Moreover, different substrates result different defect microstructures, 120o twin for
film grown on (0001) sapphire, 180o(single) twin on (1120) and no twin on (0112) have been observed,
which also depend on the surface symmetry of the substrate and the mismatch between the sapphire and the
film
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