Selective Area Growth of High-Quality ZnO Nanosheets Assisted by Patternable AlN Seed Layer for Wafer-Level Integration

Abstract

In this work, a novel patternable seed layer of aluminum nitride (AlN) is proposed as promoter of high aspect ratio zinc oxide (ZnO) laminar nanosheets (NSs) under mild hydrothermal growth conditions. High-quality NSs are selectively grown on the patterned AlN seed layer showing a great uniformity and a surface coverage higher than 90%. Additionally, compared to the standardized growth of ZnO nanowires (NWs) in analogous conditions, this method is demonstrated to be much faster and to have higher reproducibility. A growth mechanism based on a local pH gradient due to AlN hydrolysis is proposed to explain the role of the AlN layer in the growth of NSs in contrast to the typical NW shape commonly obtained by standard hydrothermal methods with other well-known seed layers (i.e., gold, gallium nitride, sapphire, ZnO, or zinc acetate). All the results indicate that the AlN buffer layer is an effective route to obtain high-quality ZnO NSs on a silicon substrate at a wafer level for very large scale integration....