The Role of Spatial and Energy Distributions of Defect Density of States in Charge Transport of Highly Disordered Insulating Materials

Charge transport and electron emission in materials is largely determined by the defect density of states for electrons within the band gap that drives electron energy loss mechanisms. For highly disordered insulating materials these spatial and energy distributions of defects are central to models of the synergistic effects underlying measurements of constant voltage conductivity, surface voltage conductivity, photoconductivity, radiation induced conductivity, permittivity, electrostatic breakdown, optical reflectivity/transmissivity, and electron emission. Analyzed together, each of these measurement methods can collectively provide complimentary information on the types of defects and the moments of their energetic and spatial distributions of the densities of defect states. We discuss how determining the moments of these distributions from such measurements provides a basic framework to explore these ubiquitous materials and their important applications.