Structural, morphological, and metal-oxide-semiconductor characteristics of thulium oxide passivation layer grown in nitrogen-oxygen-nitrogen ambient

Abstract

Poor crystallinity of the as-deposited thulium oxide (Tm2O3) passivation layer deposited via radio frequency magnetron sputtering was improved after post-deposition annealing in nitrogen‑oxygen‑nitrogen ambient at different temperatures (500, 600, 700, and 800 °C). The nitrogen ions were incorporated into all of the investigated Tm2O3 passivation layers, accompanied with the generation of oxygen vacancies (Vo). The effects of nitrogen introduction on structural, morphological, and metal-oxide-semiconductor characteristics of Tm2O3 passivation layers were systematically investigated. Results indicated that the variation of the lattice parameter a (1.0447–1.0482 nm), band gap (direct band gap: 5.037–5.292 eV, indirect band gap: 4.059–5.063 eV), root-mean-square roughness (1.40–2.20 nm), dielectric constant, k (7.6–16.0), and the interface quality were evidenced to be closely related to the introduction of nitrogen, as well as the generation of Vo after post-deposition annealing at 600 and 700 °C, which would be partly annihilated at 800 °C. Furthermore, the presence of nitrogen near the interface could restrain the formation of interfacial layer. The highest k value (16.0) was obtained by the Tm2O3 passivation layer subjected to post-deposition annealing at 700 °C while the best interface quality was acquired at 800 °C shown by the acquisition of approximately 1011 cm−1 for the interface trap density. Detailed exploration of the corresponding variation arisen from post deposition annealing in nitrogen‑oxygen‑nitrogen ambient at different temperatures was studied and compared.