ZnO nanocrystals on surfaces thermally cleaned in ultrahigh vacuum and characterized using spectroscopic photoemission and low energy electron microscopy
SEM images of ZnO nanocrystals spin-coated on surface from a 2 mg/ml dispersion. Electron acceleration voltage was 20 keV. Scale bars are 100 nm in (a) and in (b).
FOV LEEM images of ZnO nanocrystals on surface. Images show approximately the same sample area after two different cleaning temperatures. (a)–(c) after and (d)–(f) after . Kinetic electron energies were 18.2 eV in (a) and (d), 24.4 eV in (b) and (e), and 32.7 eV in (c) and (f). Ellipses in (d)–(f) mark area that shows LEEM intensity variations at different electron energies. Squares in (d)–(f) mark area enlarged in Figs. 5(a)–5(c).
(Color online) spectra acquired from ZnO nanocrystals on surface. Spectra in (a) and (b) are acquired after thermal cleaning at from full line circles in Fig. 4. The two upper spectra in (c) are acquired after thermal cleaning at and the two lower after . Full line spectra in (c) (red online) were acquired from within full line circles in Fig. 4 and dashed spectra from within dashed circles in Fig. 4.
FOV XPEEM images of ZnO nanocrystals on surface after thermal cleaning at . Images show complementarity between (a) Si from and (b) Zn . Images were acquired using a photon energy of 130 eV. White circles mark acquisition areas for spectra in Fig. 4. Square in (b) mark area enlarged in Fig. 5(d).
LEEM and XPEEM images from the same sample area showing ZnO nanocrystals on surface. LEEM images acquired at kinetic electron energies of 18.2 eV in (a), 24.4 eV in (b), and 32.7 eV in (c) show LEEM intensity variations from ZnO nanocrystals. (d) is a Zn XPEEM image showing ZnO nanocrystal coverage. Image sizes .
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