Engineering Strain and Texture in Ferroelectric Scandium-Doped Aluminium Nitride

Materials and interfacial engineering yielded ferroelectricity in Al1-xScxN films of 15 nm thickness for the first time. Bottom electrodes were explored and selected for optimal properties through modification of the strain state and thus the texture in the films. Pt bottom interfaces were shown to be the best for the widest doping window of Sc in the structure and the lowest leakage. Mo bottom interfaces promoted mixed texture in the films, which led to a reduced breakdown E-field and a reduced doping window. Top electrode stacks were shown to modify strain state and effect leakage, enabling full interfacial engineering of this material. Here, Mo top electrode interfaces caused a reduction of the coercive electric field, thus allowing strain engineering of this material and opening the door to application in memory devices.

Automated summary

Ferroelectricity was achieved in 15 nm thick Al1-xScxN films for the first time through materials and interfacial engineering. Bottom electrodes were optimized through modification of strain state and texture in the films, with Pt bottom interfaces showing the widest doping window and lowest leakage. Mo bottom interfaces promoted mixed texture, leading to reduced breakdown E-field and doping window. Top electrode stacks were found to modify strain state and leakage, enabling full interfacial engineering. Mo top electrode interfaces reduced the coercive electric field, allowing strain engineering and application in memory devices.