CRYSTALLOGRAPHIC TILTING OF HETEROEPITAXIAL LAYERS
CRYSTALLOGRAPHIC TILTING OF HETEROEPITAXIAL LAYERS
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DOI：
10.1016/0022-0248(91)90077-i
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发表时间：
1991-09-01
影响因子：
1.8
通讯作者：
SCHOWALTER, LJ
中科院分区：
文献类型：
--
作者：
AYERS, JE;GHANDHI, SK;SCHOWALTER, LJ
Mismatched heteroepitaxial layers generally exhibit a crystallographic tilt with respect to their vicinal substrates, but this phenomenon is poorly understood. Two models have been proposed for tilted epitaxy previously. The Nagai model considers the mismatch at surface steps on vicinal substrates and the misfit dislocation theory considers misfit dislocations with inclined Burgers vectors as the primary cause of tilted epitaxy. Neither of these theories applies in the general case, however. The misfit dislocation theory does not consider the mechanism of the preferential introduction of dislocations with a particular orientation, and therefore does not predict the direction of tilted epitaxy. Here a general theory for tilted epitaxy is proposed, including both contributions cited above. We propose that the preferential glide of certain Burgers orientations is the result of vicinal substrates, commonly used in heteroepitaxy, which create an asymmetry in the stresses for the various active slip systems. If the substrate inclination is about an axis of symmetry, then the tilt of the epitaxial growth is about the same axis, and its sign is determined by the nature of the mismatch: the relief of compressive strain results in negative tilt whereas the relief of tensile strain results in positive tilt. The exact amount of tilt will depend on the dynamics of strain relaxation. Upper and lower limits for the tilt have been derived. The observed tilt angle contains information on how the relaxation process took place.
