Single‐Source Precursors for the Chemical Vapor Deposition of Iron Germanides

The reaction of GeCl₂ ⋅ 1,4-dioxane with Fe₂(CO)₉ gives [Cl₂GeFe(CO)₄]₂, Cl₂Ge[Fe₂(CO)₈]Ge[Fe₂(CO)₈] or Ge[Fe₂(CO)₈]₂, depending on the educt ratio. [Cl₂GeFe(CO)₄]_2, Ge[Fe₂(CO)₈]₂ and ^Me₂iPr₂NHC ⋅ GeCl₂ ⋅ Fe(CO)₄ were characterized in their thermal decomposition behavior and applied as single source precursors in chemical vapor deposition, resulting in Fe_xGe_1-x thin films.

Abstract

Binary iron-germanium phases are promising materials in magnetoelectric, spintronic or data storage applications due to their unique magnetic properties. Previous protocols for preparation of Fe_xGe_y thin films and nanostructures typically involve harsh conditions and are challenging in terms of phase composition and homogeneity. Herein, we report the first example of single source chemical vapor deposition (CVD) of Fe_xGe_y films. The appreciable volatility of [Ge[Fe₂(CO)₈]₂], [Cl₂GeFe(CO)₄]₂ and ^Me₂iPr₂NHC ⋅ GeCl₂ ⋅ Fe(CO)₄ allowed for their application as precursors under standard CVD conditions (^Me₂iPr₂NHC=1,3-diisopropoyl-4,5-dimethylimidazol-2-ylidene). The thermal decomposition products of the precursors were characterized by TGA and powder XRD. Deposition experiments in a cold-wall CVD reactor resulted in dense films of Fe_xGe_y. During the optimization of synthetic conditions for precursor preparation the new iron-germanium cluster Cl₂Ge[Fe₂(CO)₈]Ge[Fe₂(CO)₈] was obtained in experiments with a higher stoichiometric ratio of GeCl₂ ⋅ 1,4-dioxane vs. Fe₂(CO)₉.

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