Seok Hwan Kim

In Situ X-ray Photoemission Spectroscopy Study of Atomic Layer Deposition of TiO 2 on SiliconSubstrate

In-situ X-ray photoemission spectroscopy (XPS) has been used to investigate the initial stages of TiO2 growth on a Si(001) substrate by atomic layer deposition (ALD). The core level spectra of Si 2p, C 1s, O 1s, and Ti 2p were measured at every half reaction in the titanium tetra-isopropoxide (TTIP)–H2O ALD process. The ligand exchange reactions were verified using the periodic oscillation of the C 1s concentration, as well as changes in the hydroxyl concentration. XPS analysis revealed that Ti2O3 and Si oxide were formed at the initial stages of TiO2 growth. A stoichiometric TiO2 layer was dominantly formed after two cycles and was chemically saturated after four cycles.

Initial reactions of ultrathin HfO2 films by in situ atomic layer deposition: An in situ synchrotron photoemission spectroscopy study

An in-depth exploration of the initial reaction and interfacial characteristics of ultrathin HfO2 films was implemented using in situ atomic layer deposition (ALD) and synchrotron radiation photoemission spectroscopy (SRPES). A newly developed Hf(mp)4 [mpu2009=u20093-methyl-3-pentoxide, OC(CH3)(C2H5)2] precursor, and H2O were adopted for the ALD of ultrathin HfO2. During the ALD process, the chemical composition and energy bandgap below the Fermi level of the HfO2 thin film were investigated at each cycle of the precursors by in situ measurements of SRPES. The Hf 4f, O 1s, and Si 2p core level and valence band spectra suggested that the initial ALD reactions yielded a Si suboxide and Hf silicate over three ALD cycles. An observation of the abnormal phenomena originating from the interfacial layer between HfO2 and Si revealed that the uniform HfO2 thin films exhibited a sufficient valence band offset as an insulating layer, which ensured that the valance band offset between Si 3p and O 2p reached to 2.78u2009eV over t...