Proximity‐Induced Ferroelectric Switching in Wurtzite/Fluorite Bilayers for High‐Performance Ferroelectric Field‐Effect Transistor

Proximity ferroelectricity, wherein polarization switching in one ferroelectric layer with a lower energy barrier can trigger switching in an adjacent ferroelectric with a higher energy barrier, has been demonstrated only in bilayers composed of structurally similar wurtzite-structured materials. This work demonstrates proximity-induced ferroelectric switching across a heterostructure composed of crystallographically and functionally dissimilar materials, wurtzite-structured AlScN and fluorite-structured HfZrO₂. The AlScN/HfZrO₂ and AlN/HfZrO₂ bilayers exhibit cooperative switching dynamics despite their contrasting symmetry and polarization behaviors. This interfacial coupling produces a unique ferroelectric response, characterized by low remanent polarization and a high coercive field. Using the AlN/HfZrO₂ bilayer, a ferroelectric field-effect transistor is fabricated on a p-type Si substrate with phosphorus-doped source and drain regions. The device shows a wide memory window with excellent retention and endurance. These results establish a versatile materials design strategy for engineering ferroelectricity via structural and functional heterogeneity.