The paper describes the use of an in-situ microscopy technique, which combines transmission electron microscopy (TEM) with scanning probe microscopy (SPM), to investigate the electrical and mechanical properties of individual silicon and germanium nanowires. Additionally, the formation of ordered arrays of size-monodisperse silicon and germanium nanowires within mesoporous silica powders and thin films using a supercritical fluid inclusion phase technique is described. In particular, we demonstrate ultra high-density arrays of germanium nanowires, up to 2 x 10(12) wires per square centimetre. These matric embedded nano-composite materials display unique optical properties such as intense room temperature ultraviolet and visible photoluminescence.

An important problem in nanotechnology is to develop a method for assembling complex, aperiodic, structures. While simple self-assembly will not be able to address this problem, programmable-, or algorithmic-, self-assembly is powerful enough to be a potential solution. Here, we address the question of how the basic properties of the constituent building blocks are related to the periodicity of the resulting assembly. By introducing the parameters unique structures, which gives a measure of the complexity of an assembly, and bond uniqueness, which gives a measure of how the building blocks fit together, we show how to quantify the structural quality of a general assembly system and present relations between the parameters. The introduced methods will be helpful when designing assembly systems to be used for direct fabrication of nanosystems or for nano-scaffolds and addressable arrays.