Copper Deposition and Growth over ZnO Nonpolar (1010) and (1120) Surfaces: A Density Functional Theory Study

Abstract

Density functional calculations have been performed on initial copper deposition and its growth over ZnO nonpolar (101̅0) and (112̅0) surfaces. On (101̅0), our results demonstrate that copper atoms first interact with dangling bonds or bonding orbital above ZnO. As the deposition increases, they form a zigzag structure along U-shaped gaps, then the surface layers fluctuate, and finally they develop into three-dimensional clusters on the surface. On (112̅0), we show that copper atoms also initially interact with dangling bonds. As the deposition increases, however, they form strips in the U-shaped gaps, then surface layers, and finally two-dimensional cages. In either case, our results fit well with experimental observations. Our results also indicate that the bonding of copper with ZnO substrate and that among adsorbed copper atoms are competitive, in the sense that copper (3d 10 4s 1 ) has limited bonding ability. Further, our results indicate that some copper atoms that strongly interact with ZnO become positively charged.