Browsing by Author "Lee, Jaebeom"
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Item Effect of Film Thickness on the Ferroelectric and Dielectric Properties of Low-Temperature (400 ⁰C) Hf₀.₅Zr₀.₅O₂ Films(American Institute of Physics) Kim, Si Joon; Mohan. Jaidah; Lee, Jaebeom; Lee, Joy S.; Lucero, Antonion T.; Young, Chandwin D.; Colombo, Luigi; Summerfelt, Scott R.; San, Tamer; Kim, Jiyoung; Kim, Si Joon; Mohan. Jaidah; Lee, Jaebeom; Lee, Joy S.; Lucero, Antonion T.; Young, Chandwin D.; Colombo, Luigi; Kim, JiyoungWe report on the effect of the Hf₀.₅Zr₀.₅O₂ (HZO) film thickness on the ferroelectric and dielectric properties using pulse write/read measurements. HZO films of thicknesses ranging from 5 to 20 nm were annealed at 400 ⁰C for 1min in a nitrogen ambient to be compatible with the back-end of the line thermal budget. As the HZO film thickness decreases, low-voltage operation (1.0V or less) can be achieved without the dead layer effect, although switching polarization (P_{sw}) tends to decrease due to the smaller grain size. Meanwhile, for 20-nm-thick HZO films prepared under the identical stress (similar TiN top electrode thickness and thermal budget), the P_{sw} and dielectric constant are reduced because of additional monoclinic phase formation.Item Large Ferroelectric Polarization of TiN/Hf₀․₅Zr₀․₅0₂ Capacitors Due to Stress-Induced Crystallization at Low Thermal Budget(Amer Inst Physics, 2018-10-22) Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Summerfelt, Scott R.; San, Tamer; Colombo, Luigi; Kim, Jiyoung; 0000-0001-7335-1053 (Lee, JS); 0000-0001-9477-5728 (Byun, Y-C); 0000-0003-0690-7423 (Young, CD); 0000-0003-2781-5149 (Kim, J); 70133685 (Kim, J); Kim, Si Joon; Narayan, Dushyant; Lee, Jae-Gil; Mohan, Jaidah; Lee, Joy S.; Lee, Jaebeom; Kim, Harrison S.; Byun, Young-Chul; Lucero, Antonio T.; Young, Chadwin D.; Kim, JiyoungWe report on atomic layer deposited Hf₀․₅Zr₀․₅0₂ (HZO)-based capacitors which exhibit excellent ferroelectric (FE) characteristics featuring a large switching polarization (45 μC/cm²) and a low FE saturation voltage (~1.5V) as extracted from pulse write/read measurements. The large FE polarization in HZO is achieved by the formation of a non-centrosymmetric orthorhombic phase, which is enabled by the TiN top electrode (TE) having a thickness of at least 90nm. The TiN films are deposited at room temperature and annealed at 400 ⁰C in an inert environment for at least 1 min in a rapid thermal annealing system. The room-temperature deposited TiN TE acts as a tensile stressor on the HZO film during the annealing process. The stress-inducing TiN TE is shown to inhibit the formation of the monoclinic phase during HZO crystallization, forming an orthorhombic phase that generates a large FE polarization, even at low process temperatures.Item Realization of Spatially Addressable Library by a Novel Combinatorial Approach on Atomic Layer Deposition: A Case Study of Zinc Oxide(American Chemical Society, 2019-05-07) Kim, Harrison Sejoon; Lee, Joy S.; Kim, S. J.; Lee, Jaebeom; Lucero, Antonio T.; Sung, M. M.; Kim, Jiyoung; 0000-0003-2781-5149 (Kim, J); 0000-0002-6488-5915 (Kim, HS); 70133685 (Kim, J); Kim, Harrison Sejoon; Lee, Joy S.; Lee, Jaebeom; Lucero, Antonio T.; Kim, JiyoungThough the synthesis of libraries of multicomponent metal oxide systems is prevalent using the combinatorial approach, the combinatorial approach has been rarely realized in studying simple metal oxides, especially applied to the atomic layer deposition (ALD) technique. In this literature, a novel combinatorial approach technique is utilized within an ALD grown simple metal oxide to synthesize a "spatially addressable combinatorial library". The two key factors in gradients were defined during the ALD process: (1) the process temperature and (2) a nonuniform flow of pulsed gases inside a cross-flow reactor. To validate the feasibility of our novel combinatorial approach, a case study of zinc oxide (ZnO), a simple metal oxide whose properties are well-known, is performed. Because of the induced gradient, the ZnO (002) crystallite size was found to gradually vary across a 100 mm wafer (10-20 nm) with a corresponding increase in the normalized Raman E 2 /A 1 peak intensity ratio. The findings agree well with the visible grain size observed from scanning electron microscope. The novel combinatorial approach provides a means of systematical interpretation of the combined effect of the two gradients, especially in the analysis of the microstructure of ZnO crystals. Moreover, the combinatorial library reveals that the process temperature, rather than the crystal size, plays the most significant role in determining the electrical conductivity of ZnO. © 2019 American Chemical Society.Item Synthesis of Two-Dimensional (2D) Materials, Tunable Hybrid Dielectric Deposition, and its Application in 2D Nanoelectronics(2019-09-09) Lee, Jaebeom; Kim, JiyoungThe semiconductor industry, which has developed and progressed based on Moore’s Law, has been approaching physical and quantum mechanical limitations in continuously scaling down the size of key building blocks in integrated circuits. In this regard, two-dimensional (2D) materials has been considered as an alternative channel materials instead of Si, since they offer the possibility of downscaling channel thicknesses to the atomic level while retaining improved electrostatic control of the devices and allowing the suppression of short channel effects. Although 2D materials, such as graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenides (TMDs), have proposed many unique properties for many advanced electronic applications for the last decade, bottom-up production methods of 2D materials with properties appropriate for specific applications must be formulated without a post-deposition transfer process. This dissertation focuses on the development of 2D materials (graphene and h-BN) deposition as well as uniform dielectrics on TMDs, using various techniques, including ALD, MLD, and CVD. First, the effect of Ni catalyst for graphitic carbon formation is studied using CVD at a high temperature of 800 °C. Then, the growth of graphene/graphite thin films directly on SiO2 is explored using diffusion-based graphitization mechanism of amorphous carbon (a-C) through Ni catalyst. Second, atomic layer deposition (ALD) of BCl3 and NH3 precursors at 600 °C is studied to deposit high-quality and scalable h-BN thin films directly on both SiO2 and 2D materials (HOPG and MoS2). Lastly, molecular atomic layer deposition (MLD) of octenyltrichlorosilane (7-OTS) with inorganic linkers, such as Al2O3 or TiO2, is explored at a low temperature of 100 °C in order to integrate ultrathin organic-inorganic hybrid dielectrics with tunable characteristics on 2D MoS2