This book reports the effects of annealing on structural, optical and electrical properties of nanostructured thin film materials including SnO2, TiO2, Ge and multi-layer TiO2-Ge thin films prepared by PVD techniques. These films were characterized using different techniques such as X-ray Diffraction, X-ray reflectivity, Rutherford backscattering, Scanning Electron Microscopy, atomic force microscopy, Raman spectroscopy, transmission spectroscopy, impedance spectroscopy and dc- resistivity measurements, etc. Annealing was responsible for pronounced changes in electrical, optical and opto-electronic properties of these films, as associated with changes in their structures, stoichiometry and stress-state. These aspects have been focused upon in 3rd-5th chapters of this book. This most prominent feature of this work was the development of nanostructured multi- layer TiO2-Ge thin films that showed variation in the band gap energy and optoelectronic properties depending on the thickness of the Ge layers and annealing temperatures. This part of the work has been focused upon in 7th and 8th chapters of this book, with a summary of the results given in 9th chapter.