A New Synthetic Method for HfS ₂ Thin Films Using MOCVD

Hafnium disulfide (HfS 2 ) is expected to surpass MoS 2 and WS 2 as a two-dimensional (2D) semiconductor, with the added advantage that its native oxide, HfO 2, is a widely used high- k dielectric. Unlike MoS 2 and WS 2, which are generally synthesized by metal–organic chemical vapor deposition (MOCVD) for semiconductor applications, HfS 2 has not yet been grown by this method, probably due to a lack of suitable precursors for depositing thin, uniform, and stoichiometric films. Here, we introduce two nitrogen-coordinated hafnium precursors, [Hf(TMSAEDMA)(NMe 2 ) 3 ] 1 and [Hf(TMSAEDMA)(NEtMe) 3 ] 2, derived from the functionalized ligand system N -trimethylsilylamino-ethane- N ′, N ′-dimethylamine (TMSAEDMA). Both complexes exhibit adequate volatility and high reactivity toward elemental sulfur, enabling MOCVD under moderate, H 2 S-free conditions. Using precursor 1, crystalline HfS 2 was deposited, confirmed by structural and compositional analyses. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed rapid surface oxidation to HfO 2 and HfO x S y, naturally forming heterostructures relevant for transistor applications. For electrical characterization, HfS 2 films were directly deposited on interdigitated electrode (IDE) structures. Their conductivity was evaluated both with the native oxide present and after capping with a thin ZnS layer, with both configurations preserving the conductivity. This work establishes the first MOCVD method for high-quality HfS 2, identifies 1 as a versatile precursor for chalcogenide growth, and provides detailed insights into oxidation pathways, highlighting the material’s potential for next-generation semiconductor devices.