Alkali-Metals on ZnO(10-10) Studied by Low-Energy Electron Diffraction and Photoelectron Spectroscopy

Abstract

The geometric and electronic properties of alkali metals (Na and Cs) on ZnO(1010) are investigated by means of photoelectron spectroscopy and low energy electron diffraction (LEED). Growth of the Na overlayer on ZnO(1010) at room temperature is characterized by layer-by-layer growth or monolayer growth followed by three-dimensional cluster growth. The Na adatoms in the first layer are in a cationic state, and the metallic phase is formed on top of the first cationic layer. Although Na deposition at room temperature does not yield any long-range ordered superstructure, annealing the Na-covered surface results in a (1×3) LEED pattern, and we propose the formation of the Na atomic chains along the Zn-O dimer rows. For the Cs adsorption system, the disordered overlayer by ionized Cs adatoms is also formed throughout the submonolayer coverage region. Unlike the Na adsorption system, heat treatment of the Cs-covered surface does not yield any ordered structure until all Cs adatoms desorb from the surface.

Angle‐resolved photoelectron spectroscopy study of hydrogen adsorption on ZnO($10\overline {1} 0$)

“…Single crystal ZnO with ($10\overline {\rm 1} 0$ ) orientation (7 × 5 × 0.5 mm 3 ) was purchased from Goodwill Co. The sample surface was cleaned according to a well‐established procedure 10. The work function of the clean surface was 4.45 ± 0.05 eV, in good agreement with the literature values 11, 12.…”

Thermally Activated Interaction of Co Growth with ZnO(101̅0) Surface

“…45,56 However, the deposition of Na on ZnO(101̅ 0) at RT produces the disordered overlayer with any coverage; the (1 × 3) ordered structure emerges on the surface that is annealed to 825 K. The ordered structure is considered to arise from the Na adatoms that form atomic chains along the Zn−O dimer rows. 44 The upward band bending observation and chains structure of Co on ZnO(101̅ 0) upon annealing are similar to those of the alkali metal (K, Na, and Cs) on ZnO(101̅ 0) reported elsewhere. Another important implication of the use of Co support catalysts is that the support can significantly affect reactivity.…”

“…The Co that is deposited on ZnO(101̅0) has characteristics different from the other metal adatoms that are deposited on the ZnO(101̅0), including those on Cu/ZnO(101̅0), , alkali metal(K, Na, and Cs)/ZnO(101̅0), ,, and Ag/ZnO(101̅0) . For a Cu/ZnO(101̅0) system, Cu adatoms grow at room temperature (RT) exclusively as three-dimensional clusters at step edges that are oriented perpendicular to the ZnO [12̅10] direction, , implying that the diffusion rate of Co on ZnO(101̅0) at RT is lower than that of Cu on ZnO(101̅0).…”

“…When the Ag-covered surface was annealed at 900 K, the Ag islands are sintered with an ordered structure that is strongly influenced by the surface structure of the ZnO(101̅0) substrate . In the alkali metal (K, Na, and Cs) on ZnO(101̅0) system, ,, initial downward bending at RT is observed because of the charge transfer between the metal and ZnO. When the surface is annealed, the thermally induced migration of the bulk O atoms and the resultant increase in the number of O atoms on the surface are responsible for upward bending on the annealed surface.…”

Electron Donor Molecule on the Oxide Surface: Influence of Surface Termination of ZnO on Adsorption of Tetrathiafulvalene

“…From the intensities of the C 1s and S 2p peaks on the TTF-covered ZnO surfaces as well as the Zn 3s peak intensity on the clean ZnO(101̅0) surface, the amounts of adsorbed TTF (ρ TTF ) are estimated, in the same manner as that employed in the literature, to be 1.7 × 10 14 , 1.3 × 10 14 , and 0.6 × 10 14 cm –2 for ZnO(0001), (101̅0), and (0001̅), respectively. These values are summarized in Table .…”