Scanning tip measurement for identification of point defects

Self-assembled iron-silicide nanostructures were prepared by reactive deposition epitaxy of Fe onto silicon. Capacitance-voltage, current-voltage, and deep level transient spectroscopy (DLTS) were used to measure the electrical properties of Au/silicon Schottky junctions. Spreading resistance and scanning probe capacitance microscopy (SCM) were applied to measure local electrical properties. Using a preamplifier the sensitivity of DLTS was increased satisfactorily to measure transients of the scanning tip semiconductor junction. In the Fe-deposited area, Fe-related defects dominate the surface layer in about 0.5 μm depth. These defects deteriorated the Schottky junction characteristic. Outside the Fe-deposited area, Fe-related defect concentration was identified in a thin layer near the surface. The defect transients in this area were measured both in macroscopic Schottky junctions and by scanning tip DLTS and were detected by bias modulation frequency dependence in SCM

Complexity science and representation in robot soccer

Complexity science is characterised by computational irreducibility, chaotic dynamics, combinatorial explosion, co-evolution, and multilevel lattice hierarchical structure. One of its main predictive tools is computer-generated distributions of possible future system states. This assumes that the system can be represented inside computers. Robot soccer provides an excellent laboratory subject for complexity science, and we seek a lattice hierarchical vocabulary to provide coherent symbolic representations for reasoning about robot soccer systems at appropriate levels. There is a difference between constructs being human-supplied and being abstracted autonomously. The former are implicitly lattice-hierarchically structured. We argue that making the lattice hierarchy explicit is necessary for autonomous systems to abstract their own constructs. The ideas are illustrated using data taken from the RoboCup simulation competition