Atomic layer deposition of Ga2O3 over a wide temperature range using a novel heteroleptic precursor (N,N-di-tert-butylacetimidamido)dimethylgallium (DBADMGa)

초록

A novel heteroleptic liquid Ga precursor, (N,N-di-tert-butylacetimidamido)dimethylgallium (DBADMGa), is developed for the atomic layer deposition (ALD) of Ga2O3 thin films across a broad temperature range. The precursor design, which combines a strongly chelating amidinate ligand with reactive methyl groups, achieves an optimal balance between thermal stability and surface reactivity. Density functional theory calculations support this design, revealing distinct bond dissociation energies for Ga–N and Ga–C bonds. Using DBADMGa with O3, self-limiting ALD growth is demonstrated from 270 to 390 °C, producing stoichiometric Ga2O3 films free of detectable carbon or nitrogen impurities. The resulting films exhibit smooth, amorphous surfaces, high optical transparency (97% at 633 nm), and temperature-insensitive electronic band structures. Exceptional conformality (97% step coverage) is achieved on 17:1 aspect-ratio hole structures, highlighting compatibility with vertically integrated device geometries. Device-level applicability is further demonstrated by incorporating Ga into In2O3-based thin-film transistors via a super-cycle ALD process, enabling systematic threshold-voltage tuning and effective off-current suppression. © 2026 Elsevier B.V.

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