title: Guanidinate-stabilized monomeric hafnium amide complexes as promising precursors for MOCVD of HfO2.
abstract: Novel guanidinato complexes of hafnium [Hf{eta2-(iPrN)2CNR2}2(NR2)2] (R2 = Et2, 1; Et, Me, 2; Me2, 3), synthesized by insertion reactions of N,N'-diisopropylcarbodiimide into the M-N bonds of homologous hafnium amide complexes 1-3 and {[mu2-NC(NMe2)2][NC(NMe2)2]2HfCl}2 (4) using a salt metathesis reaction, are reported. Single-crystal X-ray diffraction analysis revealed that compounds 1-3 were monomers, while compound 4 was found to be a dimer. The observed fluxional behavior of compounds 1-3 was studied in detail using variable-temperature and two-dimensional NMR techniques. The thermal characteristics of compounds 1-3 seem promising for HfO2 thin films by vapor deposition techniques. Metal-organic chemical vapor deposition experiments with compound 2 as the precursor resulted in smooth, uniform, and stoichiometric HfO2 thin films at relatively low deposition temperatures. The basic properties of HfO2 thin films were characterized in some detail.
authors.affiliation: Inorganic Materials Chemistry Group, Lehrstuhl für Anorganische Chemie II, Ruhr-University Bochum, D-44780 Bochum, Germany.
authors.forename: Andrian
authors.initials: A
authors.lastname: Milanov
authors.forename: Raghunandan
authors.initials: R
authors.lastname: Bhakta
authors.forename: Arne
authors.initials: A
authors.lastname: Baunemann
authors.forename: Hans-Werner
authors.initials: HW
authors.lastname: Becker
authors.forename: Reji
authors.initials: R
authors.lastname: Thomas
authors.forename: Peter
authors.initials: P
authors.lastname: Ehrhart
authors.forename: Manuela
authors.initials: M
authors.lastname: Winter
authors.forename: Anjana
authors.initials: A
authors.lastname: Devi