Characterization of nano-ZnO using SPELEEM and STMLeif Ericsson1, Kjell Magnusson1 and Alexei Zakharov21) Karlstad University, Sweden, 2) MAX-lab, Lund University, SwedenFuture functional applications of nanostructured ZnO, a wide bandgap semiconductor, include optical, electronic, optoelectronic, photovoltaic and piezoelectric devices. Much of the previous research has mainly concerned synthesis and growth of ZnO in different forms. In a previous survey, we have studied commercially available nanoparticles (Alfa Aesar GmbH, Germany) with an average size of 70 nm, in dispersions spin coated on SiO2/Si(001) surfaces. Using 2-10 mg/ml in ethanol and using ultrasound, we have prepared surfaces with a varying number of separated individual nanoparticles. These particles have been characterized with SEM and AFM, to reveal variations in morphology and size, and degree of agglomeration.In the present study, we have used Low-Energy Electron Microscopy (LEEM) and Photoemission Electron Microscopy (PEEM), the latter using synchrotron radiation, to further characterize the ZnO nanoparticles in terms of crystallinity, chemical state and electronic properties. The experiments have been done at MAX-lab, Lund, Sweden, at Beamline I311, using a system supplied by ELMITEC GmbH, Germany. In addition to microscopy, X-ray Photoelectron Spectroscopy from selected areas down to 1,3 micrometer, micro-XPS, has been used, yielding detailed spectroscopic information with this degree of lateral resolution.After a low-temperature anneal at 500 °C, LEEM images from 25 micrometer show strong (0,0)-reflections from separated areas of sizes down to less than 100 nm, in accordance with expectations for the size of the ZnO particles. Different electron energies show reflections from different grains due to orientation of the nanoparticles. Further annealing at 650 °C improves the LEEM image, yielding evidence for a fair degree of crystallinity and surface cleanliness in accordance with peak intensities from micro-XPS.The chemical state and electronic properties of both ZnO particles and SiO2/Si(001) substrate were studied with micro-XPS and PEEM, yielding well-resolved peaks from Zn 3d and Si 2p, which were used to create PEEM images with a perfect complementarity between Zn 3d and Si 2p based images. micro-XPS from ZnO nanoparticle agglomerates, ZnO free SiO2/Si(001) surface as well as mixed areas has been collected, showing differences in binding energies.For characterization of atomic structure and electronic structure with yet higher lateral resolution, Scanning Tunneling Microscopy and Spectroscopy, STM-STS, has been applied and preliminary result will be presented.