Selective Hydroxylation of In₂O₃as A Route to Site-Selective Atomic Layer Deposition

Several atomic layer deposition (ALD) processes are now known that leverage the distinct surface chemistry of two disparate substrates (e.g., metal vs oxide) to realize markedly different ALD nucleation rates in an approach referred to as area-selective ALD. In contrast, few ALD processes have been identified that allow selective reaction at distinct surface sites of a single material surface, in a process that might be called site-selective ALD (SS-ALD). We describe one potential strategy to discriminate among several distinct surface sites on bixbyite In₂O₃to achieve site selectivity. Using density functional theory, we predict the discriminant hydration and hydroxylation of In₂O₃terrace and step-edge sites that depend strongly on the substrate temperature at low water coverage. Infrared measurement of surface hydroxyls on In₂O₃nanoparticles supports the predicted temperature dependence. The in situ examination of MgO ALD nucleation also shows results consistent with the predicted temperature dependence of In₂O₃hydroxylation.