Thin Ga₂O₃ insertion layer for phase structure and electrical property evolutions in ferroelectric Hf_0.5Zr_0.5O₂ capacitors

In this study, gallium oxide (Ga₂O₃) insertion layers (ILs) of varying thicknesses were embedded within Hf_0.5Zr_0.5O₂ (HZO) films using atomic layer deposition (ALD). Devices with Ga₂O₃ ILs grown for fewer than 4 ALD Ga₂O₃ cycles exhibit a reduction in both remnant polarization (P _r) and coercive field (E _c). Notably, the device incorporating a IL with 2 ALD Ga₂O₃ cycles demonstrates strong performance, achieving a 2P _r of 47.0μC/cm² and an E _c of 0.92MV/cm. In contrast, for devices with ILs exceeding 8 ALD Ga₂O₃ cycles, the 2P _r value remains near 18μC/cm², while E _c increases significantly. These divergent behaviors can be attributed to the different diffusion states of the insertion IL. For a low number of ALD Ga₂O₃ cycles, it is the diffusion of Ga³⁺ ions into the HZO region adjacent to the IL that results in a reduced E _c. Conversely, with higher ALD Ga₂O₃ cycles, the IL forms a continuous layer that physically divides the 10nm HZO film into two sections, which leads to a further decrease in P _r and an increase in E _c. Furthermore, the progressive disruption of vertical grain boundaries by the growing insertion layer (IL) leads to a continuous decrease in leakage current. This work demonstrates the effective modulation of HZO devices via a Ga₂O₃ insertion layer, offering a methodology and data reference for enhancing device reliability.