Position-controlled AlN/ZnO coaxial nanotube heterostructure arrays for electron emitter applications

We studied the fabrication and field-emission characteristics of position-controlled AlN/ZnO nanotube heterostructure arrays. AlN layers with various thicknesses from 20 to 52 nm were deposited coaxially on the position-controlled ZnO nanotube arrays. The field-emission properties of the coaxial AlN/ZnO nanotube arrays were controlled using the AlN thickness and the nanotube interdistance. As compared to the bare ZnO nanotube arrays, the AlN-coated coaxial nanotube arrays exhibited enhanced electron emission, and the optimum AlN coating layer thickness on the nanotube tips was 26 nm. The improved field emission from the coaxial nanotube heterostructures is attributed to the low electron affinity and the thickness modulation effect of the AlN coating layer.