Colloquium：Stabilizing forces acting on polar surfaces of ionic semiconductors(Dr. Hu Xu , June 3)

Colloquium

Title:  Stabilizing forces acting on polar surfaces of ionic semiconductors

Speaker:  Hu Xu,  South University of Science and Technology of China

Location: Room 111, Physics Building

Time: 15:00-16:00, Wed, June 3 , 2015

Abstract:

At first glance, the stability of polar faces of ionic crystals seems a mystery. Because their layers are alternately made up of oppositely charged ions, a net dipole moment accumulates along the crystal’s c axis so in principle, the electrostatic energy of a macroscopic crystal bounded by polar surfaces should diverge proportionally as the sample thickness. Nonetheless, a number of stable ionic polar faces occur in nature. Among these, the Zn-terminated (0001) and O-terminated (000-1) faces of ZnO have received widespread attention because these surfaces are active in catalytic and corrosion reactions. In this talk, I shall explain the competing forces acting to stabilize the polar surfaces of ZnO.