Reliable Accessibility of Intermediate Polarization States in Textured Ferroelectric Al_0.66Sc_0.34N Thin Film

Ferroelectric materials are promising candidates for neuromorphic computing synaptic devices due to the nonvolatile multiplicity of spontaneous polarization. To ensure a sufficient memory window, ferroelectric materials with a large coercivity are urgently required for practical applications in highly scaled multi-bit memory devices. Herein, a remarkable reliability of intermediate ferroelectric polarization states is demonstrated in a textured Al_0.66Sc_0.34N thin film with a coercive field of 2.4 MV/cm. Al_0.66Sc_0.34N thin films were prepared at 300 °C on Pt (111)/Ti/SiO₂/Si substrates using a radio frequency reactive sputtering method. Al_0.66Sc_0.34N thin films exhibit viable ferroelectricity with a large remanent polarization value of >100 mC/cm². Through the conventional current-voltage characteristics, polarization switching kinetics, and temperature dependence of coercivity, the reproducibility of multiple polarization states with apparent accuracy is attributed to a small critical volume (3.7 × 10⁻²⁸ m³) and a large activation energy (3.3 × 10²⁷ eV/m³) for nucleation of the ferroelectric domain. This study^[1] demonstrates the potential of ferroelectric Al_1-xSc_xN for synaptic weight elements in neural network hardware.

[1] T. Y. Lee, M. S. Song, J. W. Cho, I. H. Choi, C. An, J. S. Lee, S. C. Chae, Adv. Electron. Mater. 2024, 10, 2300591