Einfluss der Al-Konzentration auf Struktur und elektrische Eigenschaften von mittels reaktivem gepulstem Magnetronsputtern gewachsenen ZnO:Al Schichten

Reactive pulsed magnetron sputtering (RPMS) is employed to grow Al-doped ZnO (AZO) films on fused silica and epitaxially on Al2O3(001). The RPMS process window for obtaining highly transparent and conductive AZO with high mobility and the influence of process parameters such as oxygen partial pressure and substrate temperature are discussed. It is shown that the optimum electrical properties depend stronly on the Al concentration of the sputtering target and that mobility on fused silica is limited to about 45 cm²/Vs. The relations between depostion conditions and film microstructure, stochiometry and electrical properties are investigated, pointing to an enrichment of Al with increasing substrate temperature leading to a deterioration of crystalline structure and carrier mobility.
Finally the observed limitations of electrical properties are categorized and discussed in terms of ionized impurity scattering and grain boundary limited transport.