Thin Lu2O3, Yb2O3, and Lu silicate layers were grown on Si using Atomic Layer Deposition (ALD), and studied mainly with X-ray photoelectron spectroscopy (XPS) and low-energy ion spectroscopy (LEIS). Experimental results on elemental composition and chemical state both in thin oxide layers and at the interface with the Si substrate, and their evolution upon different heat treatments, are presented. Besides oxygen states attributed to stoichiometric RE2O3 (RE=Lu, Yb) and OH–, an additional, loosely bound state is identified in a subsurface layer at equilibrium conditions for both Lu2O3 and Yb2O3 layers. A variety of thin (amorphous) Lu silicate films grown by ALD with different compositions depending on the precursor and/or growth conditions was unambiguously established by XPS, the components’ chemical shifts found to be a monotonous function of the composition. As grown continuous ultrathin (≤ 5nm) Lu and Yb oxide films on Si appear to consist of a hydroxide on top and of a silicate layer, ~ 1–3 nm in thickness, at the interface with the Si substrate, the stack is converted into amorphous silicates upon post-deposition annealing in N2 and appears further stable on Si at least up to annealing at T=1100∘C (in N2).
71.55.-i; 72.80.Sk; 73.20.At; 75.47.Lx; 77.55.+f
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Authors and Affiliations
1.Department 25 (Solid State Engineering)Moscow Engineering Physics InstituteMoscowRussian Federation