Structural and magnetic quality of epitaxial spinel ferrite thin films grown by plasma-enhanced atomic layer deposition

Spinel ferrite thin films have a potential to establish room-temperature spin-filtering, which has practical applications in emerging logic, memory, and sensor devices. The real-life device applications require fabrication processes that are compatible with large-scale manufacturing and microelectronics processing conditions. To address this need, we have developed a plasma enhanced atomic layer deposition (ALD) methodology for high-quality epitaxial Ni- and Co ferrite thin films ((Ni,Co)Fe2O4) with room-temperature ferrimagnetic properties. We will use polarised neutron reflectometry (PNR) to measure the magnetisation profile of these films, and investigate their magnetic uniformity and presence of dead layers at the film/substrate interface or film surface. This information in critical for the future steps of film integration in CMOS-based spin filter devices.

尖晶石铁氧体薄膜具备实现室温自旋过滤的潜力，该技术在新兴逻辑、存储与传感器件中具有实际应用价值。实际器件的落地应用要求其制备工艺需兼容大规模制造与微电子加工工况。为满足这一需求，我们开发了等离子体增强原子层沉积（plasma enhanced atomic layer deposition, ALD）工艺，用于制备兼具室温亚铁磁特性的高质量外延镍钴铁氧体薄膜((Ni,Co)Fe₂O₄)。我们将采用极化中子反射术（polarised neutron reflectometry, PNR）表征此类薄膜的磁化剖面，并研究其磁均匀性，以及薄膜/衬底界面或薄膜表面是否存在死层。该信息对于后续将薄膜集成于基于互补金属氧化物半导体（Complementary Metal Oxide Semiconductor, CMOS）的自旋过滤器件的研究环节至关重要。