Seminar with Professor Zetian Mi of the University of Michigan

Ferroelectricity has historically been associated primarily with complex oxides, while III-nitride semiconductors are best known for their exceptional chemical stability, large bandgaps, and strong spontaneous and piezoelectric polarization. Recent discoveries have revealed an unexpected connection between these two material classes: incorporation of group-IIIB elements such as Sc and Y can transform conventional III-nitrides into robust ferroelectrics while simultaneously producing dramatic enhancements in their dielectric, piezoelectric, electronic, and optical responses.

In this presentation, Zetian Mi of the University of Michigan will discuss the materials physics underlying this emerging class of ferroelectric semiconductors. He will first describe how alloying reshapes the structural and energetic landscape of wurtzite nitrides, enabling giant piezoelectric responses and polarization reversal. He will then discuss ferroelectric switching, polarization dynamics, and the nucleation and motion of domain walls, including unusual charged horizontal domain walls and their interaction with electronic charge. These phenomena reveal a rich coupling among crystal structure, polarization, defects, carriers, and interfaces that is distinct from that of conventional oxide ferroelectrics.