Control of ZnO nanorod array density by Zn supersaturation variation and effects on field emission

Abstract

We demonstrate control of ZnO nanorod density for self-organized growth on ZnO buffer layers on Si by varying Zn supersaturation during the initial growth phase, thereby altering the competition between 2D and 1D growth modes. Higher initial supersaturation favours nanorods of diameter <200 nm with micron-sized bases, resulting in low density nanorod arrays; nanorods grown with lower initial supersaturation have diameters <200 nm along their entire length, yielding higher density arrays. Field emission and imaging studies reveal field enhancement factors of >1000, attributed to sharp facet edges, and indicate that lower density arrays have more uniform emission due to a reduction in screening effects.

Origin of the 3.331 eV emission in ZnO nanorods: Comparison of vapour phase transport and pulsed laser deposition grown nanorods

“…The (002) [6,7] and are comparable (albeit slightly larger than) the values for our PLD-grown ZnO nanorods. These data further indicate the highly textured nature (with caxis orientation) of the nanorod deposits and the high crystalline quality of these materials compared to literature reports.…”

“…The lengths and widths of the VPT-grown ZnO nanorods were extracted using 'Image J' software [19] and are in the range of 1. larger values than in previous works [6,7]. ZnO nanorods is much greater than both the PLD-grown ZnO seed layer and the PLD-grown nanorods in both the near band edge and visible spectral regions (the latter shown in Fig.…”

“…This boat was then loaded into the furnace for the nanorod growth. Further details concerning the growth process are reported elsewhere [5,6,15].…”

“…Many deposition techniques including vapour phase transport (VPT) [5][6][7][8][9], metal-organic chemical vapour deposition (MOCVD) [1,10], hydrothermal deposition [11], pulsed laser deposition (PLD) [12], electrochemical deposition [13], and chemical bath deposition (CBD) [14] have been used to grow vertically aligned ZnO nanorods with good crystalline quality and optical properties.…”

Control of ZnO nanowire arrays by nanosphere lithography (NSL) on laser-produced ZnO substrates

“…However, strong control of the morphology of nanowire arrays produced for this purpose is required. Array density has been shown to have a large impact on the efficiency and uniformity of FE devices [4]. This control over array morphology can be achieved using nanosphere lithography (NSL) and there are many examples in the literature of well ordered, periodical arrays of ZnO nanowires grown via the use of NSL [5][6][7][8][9] to create an initial ordered template of metal islands on a substrate.…”