A MATHEMATICAL-MODEL FOR THE INFLUENCE OF DEEP-LEVEL ELECTRONIC STATES ON PHOTOELECTROCHEMICAL IMPEDANCE SPECTROSCOPY .1. THEORETICAL DEVELOPMENT

A mathematical model is developed to calculate the impedance response of a semiconductor electrode to a sinusoidal current perturbation under subbandgap monochromatic illumination. The model accounts explicitly for electron and hole transport as well as generation and recombination through band-to-band mechanisms and through bulk deep-level electron acceptors of specified energy. The model results are compared to experiment and illustrate how the impedance response obtained under monochromatic subbandgap illumination can be used to identify the energy, density, distribution, and recombination rate constants associated with deep-level electronic states. This may have application to in situ characterization of semiconductor-electrolyte interfaces and to characterization of solid-state materials and devices.