title: Perfect crystals grown from imperfect interfaces.
abstract: The fabrication of advanced devices increasingly requires materials with different properties to be combined in the form of monolithic heterostructures. In practice this means growing epitaxial semiconductor layers on substrates often greatly differing in lattice parameters and thermal expansion coefficients. With increasing layer thickness the relaxation of misfit and thermal strains may cause dislocations, substrate bowing and even layer cracking. Minimizing these drawbacks is therefore essential for heterostructures based on thick layers to be of any use for device fabrication. Here we prove by scanning X-ray nanodiffraction that mismatched Ge crystals epitaxially grown on deeply patterned Si substrates evolve into perfect structures away from the heavily dislocated interface. We show that relaxing thermal and misfit strains result just in lattice bending and tiny crystal tilts. We may thus expect a new concept in which continuous layers are replaced by quasi-continuous crystal arrays to lead to dramatically improved physical properties.
authors.affiliation: Laboratory for Solid State Physics, ETH-Zürich, Schafmattstrasse 16, 8093 Zürich, Switzerland. cfalub@phys.ethz.ch
authors.forename: Claudiu V
authors.initials: CV
authors.lastname: Falub
authors.forename: Mojmír
authors.initials: M
authors.lastname: Meduňa
authors.forename: Daniel
authors.initials: D
authors.lastname: Chrastina
authors.forename: Fabio
authors.initials: F
authors.lastname: Isa
authors.forename: Anna
authors.initials: A
authors.lastname: Marzegalli
authors.forename: Thomas
authors.initials: T
authors.lastname: Kreiliger
authors.forename: Alfonso G
authors.initials: AG
authors.lastname: Taboada
authors.forename: Giovanni
authors.initials: G
authors.lastname: Isella
authors.forename: Leo
authors.initials: L
authors.lastname: Miglio
authors.forename: Alex
authors.initials: A
authors.lastname: Dommann
authors.forename: Hans
authors.initials: H
authors.lastname: von Känel