Secondary electron emission properties of III-nitride/ZnO coaxial heterostructures under ion and X-ray bombardment

The secondary electron emission (SEE) yield of heterostructures of zinc oxide (ZnO) nanoneedles coaxially coated with aluminum nitride (AlN) or gallium nitride (GaN) has been studied using ion and X-ray beams. This paper describes experiments performed with ions (2 MeV protons and 3.6 MeV/nucleon carbon beams) and photons (synchrotron radiation at ≈1 keV). The SEE yield of the heterostructures is enhanced significantly by the intrinsic nanostructure of the ZnO nanoneedle templates as compared to the AlN and GaN thin films on silicon (Si) substrates [T.J. Vink, R.G.F.A. Verbeek, V. Elsbergen, P.K. Bachmann, Appl. Phys. Lett. 83 (2003) 2285]. One of the mechanisms responsible for SEE yield enhancement can be attributed to the larger area of the nanostructured surface.