Atomic layer deposition of complex thin films

Atomic layer deposition (ALD) is an advanced method for fabricating thin films on various substrate chemistries and architectures. It is employed commercially in semiconductor industry where typically thin films of binary oxides are employed in high-tech devices. Simple binary films have many useful properties, but to exploit the whole potential of the nanoscale devices, studies on more complex materials are required. Ternary and quaternary compounds possess several potentially exciting properties, but so far the studies on these complex ALD-fabricated thin films have been relatively scarce. Device thicknesses measured in nanometers can bring astonishing advantages for a number of frontier applications such as solid oxide fuel cells. For example, thin film cathodes benefit in massively lowered operation temperatures due to the exclusion of the bulk properties of the material. In this dissertation, ALD processes were developed for SrCoO3-d and (La,Sr)CoO3-d thin films to complete the set of ALD processes for one of the best cathode materials, (La,Sr)(Co,Fe)O3-d, and to gain deeper understanding of the growth of complex oxide films in general.Moreover, the dissertation studies concerned a relatively new class of materials, i.e. hybrid atomic/molecular layer deposition (ALD/MLD) fabricated inorganic-organic hybrid thin films, where different metal cations and organic molecules are mixed together creating materials which combine the best properties from the both worlds. When this dissertation research was initiated, ALD/MLD processes had been developed only for Al, Ti and Zn metal constituents, and practically only diols has been used as organic constituents. In this dissertation, di- and tricarboxylic acids are presented as highly reactive organic precursors even with the stable but vastly applied β-diketonate precursors to deliver copper, cobalt, manganese and calcium based hybrid ALD/MLD thin films with exciting structural features.