The a-axis lattice parameter of Bi2Se3 is
almost identical to the lattice periodicity of the InP (1 1 1) surface. We
consequently obtain remarkably smooth Bi2Se3 (0 0 0 1) layers in
hot-wall-epitaxy growth on InP (1 1 1)B substrates. The lattice-matched
periodicity is preserved in the [1 1 0] and [] directions of the (0 0 1)
surface. The Bi2Se3 layers grown on InP (0 0 1) substrates exhibit 12-fold
in-plane symmetry as the [] direction of Bi2Se3 is aligned to either of the two
directions. When the (1 1 1)-oriented InP substrates are inclined, the Bi2Se3 (0 0 0 1)
layers are found to develop steps having a height of ~50 nm. The tilting of the
Bi2Se3 [0 0 0 1] axis with respect to the growth surface is responsible for the
creation of the steps. Epitaxial growth is thus evidenced to take place rather
than van der Waals growth. We point out its implications on the surface states
of topological insulators.
Source:IOPscience
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