Zinc oxide films prepared via the lateral growth of aligned nanorod arrays

Continuous polycrystalline zinc oxide films 5 to 15 μm in thickness have been produced on both single-crystal silicon and transparent amorphous glass substrates via the growth of aligned nanorod arrays by chemical vapor deposition followed by lateral growth of the nanorods. The growth of the lateral faces of the nanorods was carried out under specially adjusted conditions in the same reactor as was used to grow the nanorods. The resultant films consisted of intergrown columnar crystals oriented along the c axis of the ZnO lattice (perpendicular to the substrate surface). The cathodoluminescence spectrum of the films was dominated by excitonic emission in the near-UV spectral region. The films had high electrical conductivity (ρ = 0.45 Ω cm), due to excess zinc. Prolonged annealing in air increased the resistivity of the films by five orders of magnitude (to ρ = 6 × 104 Ω cm). According to X-ray diffraction and Raman spectroscopy data, the films had good structural perfection, comparable to that of zinc oxide nanorods.