In-situ X-ray Scattering & Diffraction: Studying the Formation of Nanostructure

Nowadays, the development of new materials is often associated with specific properties of functionalized nanostructures. X-ray investigations are a very important tool to find the link between the functional (magnetism, luminescence) and the corresponding structural properties (size, orientation etc.) that are generating this function and to explain the underlying physical processes. This knowledge makes it possible to design new materials with specific properties.
Modern synchrotron sources give us the possibility to study the nanostructure during deposition. A sputtering chamber mounted on a six-circle goniometer allows an insight into the growth of nanostructures using different scattering and diffraction methods. We report on an in-situ X-ray investigation of a self-assembled growth of Ge nanocrystals embedded in a dielectric matrix forming a BCC-like super structure. A single some 100nm thick Ge+Al2 O3 layer using magnetron sputtering was deposited at an elevated substrate temperature. The self-assembly during growth or subsequent annealing results in the formation of a well ordered three-dimensional BCC-like quantum dot lattice within the whole deposited volume. The parameters of the formed super structure can be directly influenced by changing the deposition parameters. The self-ordering of the quantum dots is explained by diffusion mediated nucleation and surface morphology effects.