The objective of the proposed research is to develop ALD process for polycrystalline BaTiO3 (BTO) thin films aimed at high-k gate oxide applications in next-generation transistors. The work focuses on establishing a clear understanding of the process – structure – property relationships in ALD BTO. We first investigated the chemistry and chemical reactions during deposition and crystallization. It is found that Ba is initially incorporated as Ba(OH)₂ in the as-grown films, which subsequently reacts with TiO₂ to form crystalline BTO upon annealing. However, Ba(OH)₂ readily converts to BaCO₃ upon exposure to ambient CO₂, introducing an undesirable kinetic barrier to crystallization. In addition, we developed the process for high-k BTO capacitors with Pt top and bottom electrodes, achieving a relative permittivity of 75 for 50 nm BTO films. Finally, future research directions include mitigating interfacial voids, scaling down the BTO thickness, and exploring doping strategies to further enhance dielectric performance