Observation of a ($\surd $3x$\surd $3)R30\r{ } Reconstruction on O-Polar ZnO Surfaces

Low energy electron diffraction revealed a previously unreported ($\surd $3x$\surd $3)R30\r{ } reconstruction on clean, O-polar ZnO surfaces after\textit{ in-situ} preparation under conditions with an extremely low H background or after \textit{ex-situ }tube-furnace annealing [1]. It has been proposed that unreconstructed, H-free, O-polar ZnO surfaces cannot be produced [2]. As the sample is prepared from the as-received surface, to a clean (1x1), and finally to the clean ($\surd $3x$\surd $3)R30\r{ } reconstruction, x-ray photoelectron spectroscopy shows decreasing intensity of the hydroxyl shoulder (located to the high-binding-energy side of the O1$s$ peak). This reconstruction is stable against H$_{2}$, N$_{2}$, and air, although its formation is suppressed when preparation occurs under an intentional H$_{2}$ background. A structural investigation of the reconstruction with LEED-IV is under way. \underline {\textbf{References:}} [1] S.T. King \textit{et al.}, Surf. Sci. \textbf{604}, L131 (2008) [2] C. W\"{o}ll, Prog. Surf. Sci. \textbf{82}, 55 (2007)