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For an electronic device well-designed interfaces are critical for the performance. Studies of interfaces down to an atomic level are thus highly motivated both from a fundamental and technological point of view. In this thesis, a surface science approach has been employed to study the formation of interfaces in systems relevant for transistor and solar cell applications. Surface science methodology entails ultra high vacuum environment, single crystalline surfaces, submonolayer control of deposited material, surface sensitive spectroscopy and atomic resolution microscopy.

The primary experimental method for characterization is electron spectroscopy. This is a family of very powerful experimental techniques capable of giving information on the atomic level. Additionally, studies have been performed using scanning tunnelling microscopy. Combined these two methods can provide an atomic level characterisation of the geometric and electronic properties of the surface.

The emphasis of this work is placed on ultra thin TiO₂ and ZrO₂ films grown on silicon substrates by means of ultra-high vacuum metal-organic chemical vapour deposition. ZrO₂ has also been grown on SiC and FeCrAl. Deposition has been performed with different process parameters. The interface region of each film has been characterised. The band alignment, a most important issue with regard to the development of new transistor devices, for the ZrO₂/Si(100) system has been explored. Decomposition pathways of the metal organic precursors have been studied in detail. Changing process parameters is shown to alter both the precursor decomposition pathway and the nature of the interface region, thus opening the possibility to tailor the material function.

The titanium dioxide films grown in situ have shown to be excellent models of nanostructured electrode materials. In this spirit, interfaces of model systems for the solid-state dye-sensitized solar cell have been studied. Links between device performance and interface structure have been elucidated.