AlxGa1-xN -GaN core-shell nanorods: Synthesis and field emission properties

Quasi-aligned AlxGa1-xN-GaN core-shell nanorods have been synthesized on Si (100) substrate by a one-step and catalyst-free chemical vapor deposition method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, and cathodoluminescence analyses reveal that the core/shell nanorods consist of AlxGa1-xN core and GaN shell. Field-emission measurements show that the AlxGa1-xN-GaN core-shell nanorod arrays present a turn-on field of ∼3.6 V/μm, threshold field of ∼4.8 V/μm, and a field-enhancement factor of ∼1197, which is much better than most AlN or GaN nanostructures. The excellent field-emission characteristics are originated from the low electron affinity of AlxGa1-xN and narrow band gap of GaN, resulting in good electron transport from AlxGa1-xN to GaN as evident from the band diagram of the core-shell material. Such AlxGa1-xN-GaN core-shell nanorods are envisaged to be one of decent candidates for advanced electronic and optoelectronic nanodevices.