title: Reverse epitaxy of Ge: ordered and faceted surface patterns.
abstract: Normal incidence ion irradiation at elevated temperatures, when amorphization is prevented, induces novel nanoscale patterns of crystalline structures on elemental semiconductors by a reverse epitaxial growth mechanism: on Ge surfaces irradiation at temperatures above the recrystallization temperature of 250 °C leads to self-organized patterns of inverse pyramids. Checkerboard patterns with fourfold symmetry evolve on the Ge (100) surface, whereas on the Ge (111) surface, isotropic patterns with a sixfold symmetry emerge. After high-fluence irradiations, these patterns exhibit well-developed facets. A deterministic nonlinear continuum equation accounting for the effective surface currents due to an Ehrlich-Schwoebel barrier for diffusing vacancies reproduces remarkably well our experimental observations.
authors.affiliation: Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Ou
authors.forename: Adrian
authors.initials: A
authors.lastname: Keller
authors.forename: Manfred
authors.initials: M
authors.lastname: Helm
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fassbender
authors.forename: Stefan
authors.initials: S
authors.lastname: Facsko