ZnO Bulk and Layer Growth -- The Scope of Zinc Oxide Bulk Growth -- Growth Mechanism of ZnO Layers -- Kinetics of High-Temperature Defect Formation in ZnO in the Stream of Oxygen Radicals -- Electrical, Optical, and Structural Properties -- Electrical Properties of ZnO -- Electrical Properties of ZnO Thin Films and Single Crystals -- Structure, Morphology, and Photoluminescence of ZnO Films -- Optics and Spectroscopy of Point Defects in ZnO -- Whispering Gallery Modes in Hexagonal Zinc Oxide Micro- and Nanocrystals -- Properties of Dislocations in Epitaxial ZnO Layers Analyzed by Transmission Electron Microscopy -- Role of Hydrogen -- Muon Spin Rotation Measurements on Zinc Oxide -- Hydrogen Donors in Zinc Oxide -- Hydrogen-Related Defects in ZnO Studied by IR Absorption Spectroscopy -- Influence of the Hydrogen Concentration on H Bonding in Zinc Oxide -- Fundamental Properties -- Valence Band Ordering and Magneto-Optical Properties of Free and Bound Excitons in ZnO -- Fundamental Optical Spectra and Electronic Structure of ZnO Crystals -- Photo-Induced Localized Lattice Vibrations in ZnO Doped with 3d Transition Metal Impurities -- Device Applications -- ZnO Window Layers for Solar Cells -- ZnO/AlGaN Ultraviolet Light Emitting Diodes -- ZnO Transparent Thin-Film Transistor Device Physics -- Zinc Oxide Thin-Film Transistors.Recently, a significant effort has been devoted to the investigation of ZnO as a suitable semiconductor for UV light-emitting diodes, lasers, and detectors and hetero-substrates for GaN. Research is driven not only by the technological requirements of state-of-the-art applications but also by the lack of a fundamental understanding of growth processes, the role of intrinsic defects and dopants, and the properties of hydrogen. The NATO Advanced Research Workshop on “Zinc oxide as a material for micro- and optoelectronic applications”, held from June 23 to June 25 2004 in St. Petersburg, Russia, was organized accordingly and started with the growth of ZnO. A variety of growth methods for bulk and layer growth were discussed. These techniques comprised growth methods such as closed space vapor transport (CSVT), metal-organic chemical vapor deposition, reactive ion sputtering, and pulsed laser deposition. From a structural point of view using these growth techniques ZnO can be fabricated ranging from single crystalline bulk material to polycrystalline ZnO and nanowhiskers. A major aspect of the ZnO growth is doping. n-type doping is relatively easy to accomplish with elements such al Al or Ga. At room temperature single crystal ZnO exhibits a resistivity of about 0. 3 -cm, an electron mobility of 2 17 -3 225 cm /Vs, and a carrier concentration of 10 cm . In n-type ZnO two shallow donors are observable with activation energies of 30 – 40 meV and 60 – 70 meV.