title: Engineered Coalescence by Annealing 3D Ge Microstructures into High-Quality Suspended Layers on Si.
abstract: The move from dimensional to functional scaling in microelectronics has led to renewed interest toward integration of Ge on Si. In this work, simulation-driven experiments leading to high-quality suspended Ge films on Si pillars are reported. Starting from an array of micrometric Ge crystals, the film is obtained by exploiting their temperature-driven coalescence across nanometric gaps. The merging process is simulated by means of a suitable surface-diffusion model within a phase-field approach. The successful comparison between experimental and simulated data demonstrates that the morphological evolution is driven purely by the lowering of surface-curvature gradients. This allows for fine control over the final morphology to be attained. At fixed annealing time and temperature, perfectly merged films are obtained from Ge crystals grown at low temperature (450 °C), whereas some void regions still persist for crystals grown at higher temperature (500 °C) due to their different initial morphology. The latter condition, however, looks very promising for possible applications. Indeed, scanning tunneling electron microscopy and high-resolution transmission electron microscopy analyses show that, at least during the first stages of merging, the developing film is free from threading dislocations. The present findings, thus, introduce a promising path to integrate Ge layers on Si with a low dislocation density.
authors.affiliation: L-NESS and Department of Materials Science, Università di Milano-Bicocca , Via R. Cozzi 55, I-20126, Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Salvalaglio
authors.affiliation: L-NESS and Department of Materials Science, Università di Milano-Bicocca , Via R. Cozzi 55, I-20126, Milano, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bergamaschini
authors.affiliation: Laboratory for Solid State Physics, ETH Zürich , Otto-Stern-Weg 1, CH-8093, Zürich, Switzerland.
authors.forename: Fabio
authors.initials: F
authors.lastname: Isa
authors.affiliation: L-NESS and Department of Materials Science, Università di Milano-Bicocca , Via R. Cozzi 55, I-20126, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Scaccabarozzi
authors.affiliation: L-NESS and Department of Physics, Politecnico di Milano , Via F. Anzani 42, I-22100, Como, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Isella
authors.affiliation: Institut für Wissenschaftliches Rechnen, Technische Universität Dresden , Zellescher Weg 12-14, D-01069, Dresden, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Backofen
authors.affiliation: Institut für Wissenschaftliches Rechnen, Technische Universität Dresden , Zellescher Weg 12-14, D-01069, Dresden, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Voigt
authors.affiliation: L-NESS and Department of Materials Science, Università di Milano-Bicocca , Via R. Cozzi 55, I-20126, Milano, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Montalenti
authors.affiliation: IHP , Im Technologiepark 25, D-15236, Frankfurt (Oder), Germany.|Department of Science, Università Roma Tre , Viale Marconi 446, I-00146, Roma, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Capellini
authors.affiliation: IHP , Im Technologiepark 25, D-15236, Frankfurt (Oder), Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schroeder
authors.affiliation: Laboratory for Solid State Physics, ETH Zürich , Otto-Stern-Weg 1, CH-8093, Zürich, Switzerland.
authors.forename: Hans
authors.initials: H
authors.lastname: von Känel
authors.affiliation: L-NESS and Department of Materials Science, Università di Milano-Bicocca , Via R. Cozzi 55, I-20126, Milano, Italy.
authors.forename: Leo
authors.initials: L
authors.lastname: Miglio
keywords: dislocations; heteroepitaxy; semiconductors; substrate patterning; surface diffusion