Lin Y.-SHoo J.-YChung T.-FYang J.-RJER-REN YANGMIIN-JANG CHEN2021-08-052021-08-05202026376113https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105983410&doi=10.1021%2facsaelm.0c00089&partnerID=40&md5=c33cc73a292cea49b450ceb02fd8c022https://scholars.lib.ntu.edu.tw/handle/123456789/576930Two-dimensional tungsten disulfide (WS2) is one of the potential channel materials in future nanoelectronics. In this paper, an atomic layer deposition (ALD) process based on low-temperature (low-T) physical adsorption and a short purge time was used for nucleation engineering to achieve a continuous Al2O3 gate oxide with a thickness of less 10 nm on WS2. No oxidation states were observed from WS2 as revealed by X-ray photoelectron spectroscopy (XPS), indicating that the nucleation of Al2O3 gate dielectrics proceeds via the physical adsorption of reactants or precursors. The sub-10 nm thickness and the low leakage current of the Al2O3 gate oxide were validated by transmission electron microscopy (TEM) and conductive atomic force microscopy (AFM) characterizations. This high-quality Al2O3 gate oxide leads to the formation of the top-gated WS2 transistor with a low subthreshold slope. Copyright ? 2020 American Chemical Society.Adsorption; Alumina; Aluminum oxide; Atomic force microscopy; Atomic layer deposition; Crystallization; Gate dielectrics; Gates (transistor); High resolution transmission electron microscopy; Leakage currents; Nucleation; Sulfur compounds; Temperature; X ray photoelectron spectroscopy; Channel materials; Conductive atomic force microscopy; Low temperatures; Low-leakage current; Physical adsorption; Process-based; Subthreshold slope; Tungsten disulfide; Tungsten compoundsjournal article10.1021/acsaelm.0c000892-s2.0-85105983410