title: Zintl Clusters as Wet-Chemical Precursors for Germanium Nanomorphologies with Tunable Composition.
abstract: [Ge9](4-) Zintl clusters are used as soluble germanium source for a bottom-up fabrication of Ge nanomorphologies such as inverse opal structures with tunable composition. The method is based on the assembly and oxidation of [Ge9 ](4-) clusters in a template mold using SiCl4 , GeCl4 , and PCl3 leading to Si and P-containing Ge phases as shown by X-ray diffraction, Raman spectroscopy, and energy-dispersive X-ray analysis. [Ge9](4-) clusters are retained using ethylenediamine (en) as a transfer medium to a mold after removal of the solvent if water is thoroughly excluded, but are oxidized to amorphous Ge in presence of water traces. (1)H NMR spectroscopy reveals the oxidative deprotonation of en by [Ge9](4-). Subsequent annealing leads to crystalline Ge. As an example for wet-chemical synthesis of complex Ge nanomorphologies, we describe the fabrication of undoped and P-doped inverse opal-structured Ge films with a rather low oxygen contents. The morphology of the films with regular volume porosity is characterized by SEM, TEM, and grazing incidence small-angle X-ray scattering.
authors.affiliation: Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany.
authors.forename: Manuel M
authors.initials: MM
authors.lastname: Bentlohner
authors.affiliation: Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Waibel
authors.affiliation: University of Munich (LMU) and Center for NanoScience (CeNS), Butenandtstrasse 5-13 (Haus E), 81377, München, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Zeller
authors.affiliation: Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-Franck-Straße 1, 85748, Garching, Germany.
authors.forename: Kuhu
authors.initials: K
authors.lastname: Sarkar
authors.affiliation: Physik-Department, Lehrstuhl für Funktionelle Materialien, Technische Universität München, James-Franck-Straße 1, 85748, Garching, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Müller-Buschbaum
authors.affiliation: University of Munich (LMU) and Center for NanoScience (CeNS), Butenandtstrasse 5-13 (Haus E), 81377, München, Germany. dina.fattakhova@cup.uni-muenchen.de.
authors.forename: Dina
authors.initials: D
authors.lastname: Fattakhova-Rohlfing
authors.affiliation: Department Chemie, Technische Universität München, Lichtenbergstraße 4, 85747, Garching, Germany. thomas.faessler@lrz.tu-muenchen.de.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Fässler
keywords: composition tuning; germanium; inverse opals; nanostructuring; zintl clusters