Correlation between ZnO nanowire growth and the surface of AlN substrate

Single-crystalline ZnO nanowires are fabricated by thermal chemical vapor transport and condensation on AlN epilayers without employing any metal catalyst. Before the growth of ZnO nanowires, the surface of AlN epilayers was treated by HF solution and then changed to a mixture of flat plane and hillocks according to dipping time. ZnO nanowires along the c-axis direction of hexagonal structures were synthesized only on the HF treated AlN surface. ZnO nanowire arrays have been obtained by selective etching by photolithography process. A mechanism for nanowire growth on modified AlN epilayer is proposed.