Doping effects on the ferroelectric properties of wurtzite nitrides

Ferroelectric materials have been explored for a long time for easy integration with state-of-the-art semiconductor technologies. Doped wurtzite nitrides have been reported as promising candidates due to their high stability, compatibility, and scalability. We investigate doping effects on ferroelectric properties of Sc-doped AlN (AlScN) and B-doped AlN (AlBN) by first-principles methods. The energy barrier against polarization switching is observed to decrease with increasing doping concentration at low concentration ranges, which is the origin of the emerging ferroelectricity in doped AlN. Further increasing the doping concentration to a critical value, the ferroelectric wurtzite phase transforms into paraelectric phases (a rock salt phase for AlScN and a zinc blende phase for AlBN), making it invalid to decrease the coercivity by increasing the doping concentration. Furthermore, it is revealed that different nonpolar structures (a hexagonal phase for AlScN and a beta-BeO phase for AlBN) appear in the ferroelectric switching pathway, generating different switching features in doped AlN. Our results give a microscopic understanding of the ferroelectricity in doped wurtzite materials and broaden the route to improve their ferroelectric properties.

Automated summary

We investigate the doping effects on the ferroelectric properties of Sc-doped AlN and B-doped AlN using first-principles methods. Our results show that the energy barrier against polarization switching decreases with increasing doping concentration, leading to the emergence of ferroelectricity in doped AlN. However, when the doping concentration exceeds a critical value, the ferroelectric phase transforms into paraelectric phases, making it ineffective to reduce coercivity by increasing doping concentration. Furthermore, different nonpolar structures appear in the ferroelectric switching pathway, resulting in different switching features in doped AlN.