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 (AIN) 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 approximate to 1 keV). The SEE yield of the heterostructures is enhanced significantly by the intrinsic nanostructure of the ZnO nanoneedle templates as compared to the AIN 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.This work was supported by NTU RGM 17/04, A*STAR/MOE RP3979908M, A*STAR 0121050038, NUS Core Support C-380-003-003-001 and the National Creative Research Initiative Project of the Ministry of Science and Technology, Korea