Impact of Scaling Thickness on the Ferroelectric Properties of Pt/Al₀.₈Sc₀.₂N/Pt Capacitors

In this work, the effects of reducing the thickness of Al0.8Sc0.2N films from 100 to 40 nm on the ferroelectric properties of Pt/Al0.8Sc0.2N/Pt capacitors were investigated. As Al0.8Sc0.2N film thickness decreases, remanent polarization significantly drops, and coercive field (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {c}}$ </tex-math></inline-formula>) increases, which origins from the diminished c-axis orientation and reduced crystalline size. Piezoresponse force microscopy results confirm polarization switching in all films, with thinner films exhibiting larger <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {c}}$ </tex-math></inline-formula> and lower initial polarization. Notably, the thinner films show the lower leakage current, attributed to a decrease in nitrogen vacancies. Moreover, thinner Al0.8Sc0.2N films exhibit better endurance performance, with a maximum switching cycle of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{5}}$ </tex-math></inline-formula> cycles achieved for the 40-nm Al0.8Sc0.2N film. These results underscore the critical role of film thickness in optimizing aluminum scandium nitride (AlScN) thin films for high-performance ferroelectric applications, providing crucial insights for future device development.