Morphology inducing selective plasma etching for AlN nanocone arrays: tip-size dependent photoluminescence and enhanced field emission properties

Abstract

The bottom-up growth method has been the main way to form various AlN nanostructures, but there still exists many problems in the lack of control and non-uniformity. Here, we adopt a firstly top-down plasma etching method to easily fabricate large-area AlN nanocone arrays on magnetron sputtered (002) AlN films, and the unique, pebble-like array morphologies of the AlN films surface greatly induce the whole selective plasma etching process without any masked process. The as-formed AlN nanocones not only keep the crystalline oriented (002) and microstructure of the original AlN film, but also have a good uniformity and controllability in the height and density, as well as the tip-size. These AlN nanocone arrays exhibited an intense broad ultraviolet emission, centered at 3.26 eV and excellent field emission properties, especially showing a tip-size dependent photoluminescence and field emission properties that were remarkably enhanced with decreasing the nanocone tip-size. Our results provide a promising route for the controllable fabrication of AlN nanostructures and practical application of AlN-based various nanodevices in optoelectronics and vacuum-nanoelectronics.