Position-Controlled Selective Growth of ZnO Nanostructures and Their Heterostructures

Abstract

Abstract In this chapter, we present a review of recent research activities related to position-controlled selective growth of ZnO one-dimensional nanostructures and their heterostructures for various device applications. The main text of this chapter is organized into three sections. The first section briefly introduces selective growth methods of ZnO nanostructures and describes the underlying growth mechanisms. It is of interest to characterize in detail the nanostructures grown by catalyst-assisted and catalyst-free methods, in an attempt to better understand the key factors required to create nanostructures with high crystallinity and low defect density for high-quality electronic and optoelectronic devices. In the second section, the position-controlled selective growth of ZnO nanostructures on various substrates and their resulting growth characteristics is reviewed. The diverse choice of substrates applicable to position-controlled selective growth of nanostructures includes various semiconducting substrates (e.g., Si, GaN, ZnO, SiC, and indium tin oxides), metallic substrates (e.g., Au, Pt, Cu, and Ag), and insulating substrates (e.g., Al 2 O 3 ), covering the vast majority of substrates used in the device industry. In particular, layered two-dimensional materials, such as graphene and hexagonal boron nitride, have recently been emerging as novel substrates for transferable and flexible optoelectronic and electronic devices. The last section focuses on the fabrication of light-emitting diodes based on ZnO nanostructures and their heterostructures with GaN and its alloys. We first introduce the initial works that used vertically aligned but randomly formed ZnO nanostructures, and then move onto more advanced nanoarchitectures enabled by position-controlled selective growth. The position-controlled selective growth is essential in creating nanostructure devices suitable for practical applications, where the nanostructures are located at precisely determined positions with designed dimensions. Selective growth is needed not only to control the position of the grown nanomaterials but also to improve the performance of devices. Finally, conclusions and perspectives on ZnO nanostructures for various device applications are presented.