Wafer-scale uniform non-ferroelectric k-phase In₂Se₃ transistors via thermal evaporation

In₂Se₃ semiconductors offer remarkable potential for next-generation electronics for processing-in-memory applications due to their high intrinsic mobility and strong ferroelectricity. However, In₂Se₃ semiconductors, which typically exist in a polymorphic phase, inherently manifest ferroelectricity due to structural asymmetry or layer sliding, which can result in data loss due to ferroelectricity when implementing logic devices. Here, we report a facile method to deposit κ-phase In₂Se₃ film with high uniformity and stable electronic properties over a large area by thermal evaporation. The thermally deposited In₂Se₃ film exhibited a unique and previously underexplored κ-phase layered structure with non-ferroelectric properties at a moderate deposition rate of 0.2 Å s⁻¹. The non-ferroelectric behavior of layered κ-In₂Se₃ is primarily attributed to the presence of a semiconducting dielectric layer above the ferroelectric layer. This dielectric layer interferes with the movement of Se atoms in the middle of the quintuple In₂Se₃ ferroelectric layer, which is crucial for enabling the material's ferroelectric properties. By leveraging the unique electronic properties of the κ-phase In₂Se₃, we successfully demonstrated high-performance In₂Se₃ field-effect transistors on 4-inch wafer with an average electron mobility of 39.25 cm² V⁻¹ s⁻¹. Additionally, we implemented a complementary inverter using p-type Se-alloyed TeOx transistors, highlighting the potential of κ-phase In₂Se₃ for advanced logic and memory applications.