Document Type

Journal Article

Department/ Unit

Institute of Computational and Theoretical Studies

Abstract

New understanding has been reached on competing forces acting to stabilize the polar surfaces of intrinsic ZnO. To compensate an accumulating dipole moment normal to ionic planes, the Madelung electrostatic force and the bonding ability of undercoordinated Zn ions compete to deplete more Zn atoms from the (0001) face and more O atoms from the (0001¯) face. In this competition, the former mechanism wins because it provides very low energy binding sites for O ions at face-centered-cubic registries on both surfaces. On the Zn-face, a distorted tetrahedral structure is formed, while on the O-face, a vertical Y structure is formed. In both structures, O ions form the topmost atomic plane. The reconstructed polar surfaces containing these novel structures have cleavage energy of 2.36 J/m2, comparable to that of nonpolar surfaces and in agreement with experimental observation. An earlier structure found on the Zn-face annealed at below 1000 K is stabilized mainly by the Madelung electrostatic force and is a metastable structure of that surface.

Publication Year

2014

Journal Title

Physical Review B

Volume number

89

Publisher

American Physical Society

First Page (page number)

235403-1

Last Page (page number)

235403-10

Referreed

1

DOI

10.1103/PhysRevB.89.235403

ISSN (print)

1550235X

Included in

Physics Commons

Share

COinS