Photodoping Effects in High Critical Temperature Superconducting Films and Josephson Junctions

Persistent photoconductivity is an interesting and unusual property of high temperature superconductors. Illumination of these compounds can lead to a change in doping that is persistent at low temperature and relaxes back to its initial value at elevated temperatures. This photodoping can give rise to an improvement of superconducting properties, which is contrary to the illumination effects in conventional superconductors. Furthermore, these photo-induced effects can also be used to probe and modify the properties of grain boundaries in grain boundary Josephson junctions. This paper reviews the experimental data and proposed theoretical models related to these photoinduced effects.