TIME-OF-FLIGHT PULSED ION-BEAM SURFACE-ANALYSIS AS A MEANS OF IN-SITU, REAL-TIME CHARACTERIZATION OF THE GROWTH OF FERROELECTRIC AND CONDUCTIVE OXIDE HETEROSTRUCTURES

Pulsed beam Time-of-Flight Ion Scattering and Recoil Spectroscopy (TOF -ISARS) surface analysis methods have been developed which permit real time, in situ characterization of the growth layer of multi-component oxide thin films. Results are presented from a study of the deposition of Pb, Zr, Ti and Ru using a sequential layer-by-layer deposition met hod under ambient oxygen pressure conditions appropriate to the growth of PZT films, revealing layer-by-layer as well as 2D and 3D island gr owth processes during deposition. Thermodynamic stability conditions r esult in modification of the layered structure during deposition, in s ome cases altering the layer ordering of the growth region. Calculatio ns using the Miedema model for surface segregation are in accord with experimental results that reveal an exchange between deposited Zr and Ti atoms and an underlying Pb layer. In addition, the room temperature studies revealed that Pb grows layer-by-layer, nucleating as 2D islan ds, while Zr tends to form three-dimensional islands. At room temperat ure, the Zr surface concentration is strongly enhanced by the presence of oxygen, but at high temperatures, surface Pb is found to be stabil ized by the presence of an oxygen ambient, illustrating the importance of real-time, in situ analysis of the growth layer as opposed to more conventional surface analytical methods which require interruption of the deposition process in order to characterize the film surface.