ScholarWorks@성균관대학교

초록

In this study, the thermal stability of WS2 crystals during O3-based atomic layer deposition (ALD) and subsequent high-temperature post-deposition annealing (PDA) processes to form ferroelectric Hf1-xZrxO2 (HZO) films was comprehensively investigated. The oxidation of approximately one monolayer and its subsequent incorporation into the HZO film during the O3-based ALD process at 260 °C were confirmed through various characterization techniques, including Raman spectroscopy, photoluminescence (PL) spectroscopy, and transmission electron microscopy analyses. This phenomenon was attributed to the high oxidizing power of the O3 oxidant, as demonstrated by comparisons with density functional theory calculations and by conducting the same experiment using H2O as the oxidant in the ALD process. Unlike MoS2, which undergoes significant oxidation-induced thermal decomposition, the WS2 monolayer remained largely intact during the PDA process in the temperature range of 400–600 °C, with only a slight suppression of the PL peak owing to the formation of sulfur vacancies. Thermogravimetric analysis further showed that WS2 exhibits superior resistance to high-temperature oxidation compared with MoS2, even at 600 °C. This study provides fundamental insights into the thermal and oxidative stabilities of WS2, which are crucial for the fabrication of nanoelectronic devices that incorporate the ferroelectric properties of HZO films. © 2025 Elsevier B.V.

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