Variable Coherence Microscopy: a Rich Source of Structural Information from Disordered Materials

Variable coherence microscopy, a tool for quantitative analysis of structural fluctuations in disordered materials, is introduced. The method involves transmission electron microscopy of thin films and uses hollow-cone illumination. Experiments were performed on annealed evaporated amorphous germanium. Although many aspects of the data agree with the continuous random network model, there is experimental evidence for additional medium-range structure on the 10-20 Å scale.