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Doped ZnO (zinc oxide) and Zn1-xMgxO belong to the material class of transparent conductive oxides (TCOs). These materials are characterized by a high optical transmittance accompanied by a low electrical resistivity that makes them crucial for a wide field of technological applications nowadays. In thin film solar cells, TCOs are employed as transparent and conductive window layers, whose quality is essential for the realization of high power conversion efficiencies. The field is not only of technological significance but also of scientific interest, since most of the basic effects governing the film properties in correlation with the use of different dopant elements, alloys, or the deposition techniques and parameters are not yet fully understood. Therefore, it is of great importance to clarify the relation between these parameters to be able to deliberately decrease the resistivity while maintaining a high optical transmittance – especially for ZnO as a contact material in thin film solar cells. In this thesis, the relation between the structural, electronic, and charge carrier transport properties of doped ZnO and Zn1-xMgxO films has been investigated in detail. A main focus was the study of the influence of the deposition process and the deposition parameters on the structural and the resulting electronic properties of the films for the application as front contact window layers in thin film solar cells. The objective was to clarify the above mentioned relations, which allows to derive solutions for a deliberate improvement of the layer properties. For the investigation, thin films deposited by magnetron sputtering at substrate temperature between ~30 °C and 500 °C with different plasma excitation frequencies in the range of DC to 27.12 MHz were used. The characterization of the electronic properties was mainly performed by means of resistivity, Hall-effect, and Seebeckcoefficient measurements, while the structural properties were primarily determined by X-ray diffraction. The investigations showed that the charge carrier transport in doped polycrystalline and epitaxial ZnO and Zn1-xMgxO layers is dominated by ionized impurity scattering and grain boundary scattering. The grain boundary scattering has been characterized by a model, which has been derived to describe the charge carrier transport over grain boundaries in semiconductors of arbitrary degeneracy. A comparison of the transport properties of the polycrystalline and epitaxial films confirmed the dominance of the grain boundary scattering even for a very low number of grain boundaries present in the material. Furthermore, this scattering is mainly caused by the segregation of the dopant material to the grain boundaries. Hence, for practical applications, the grain boundary scattering could only be reduced by lowering the amount of dopant material in the films. The influence of the most important deposition parameters on the electronic and structural properties was explained by a model derived on the basis of a comparison of ion energy distributions measured for the magnetron sputtering process with the resulting film properties. According to this model, the properties of the films are mainly influenced by the formation of electrically active acceptor-like oxygen interstitial (Oi) defects at low deposition temperatures Tsub, which lead to a partial compensation of the extrinsic donor. At higher Tsub, the formation of secondary phases or defect complexes, in which the dopant is also electrically inactive, prevails. Additionally, the generally lower free carrier concentrations in the Zn1-xMgxO:Al films can be explained as a result of a stronger compensation of the extrinsic dopant due to a stronger bombardment of the growing films. Concluding

The relation between the deposition process and the structural, electronic, and transport properties of magnetron sputtered doped ZnO and Zn1-xMgxO films