Long–lived femtosecond photon echo in thin films on localized exciton states at room temperature

Abstract

Long–lived femtosecond photon echo was excited at room temperature in a two–photon regime on the charged exciton states (trion type) localized on the surface defects of a three–layer textured ZnO/Si(B)/Si(P) film with the thickness of each layer at 100 nm in a longitudinal uniform magnetic field. The irreversible longitudinal relaxation time T1 for the long–lived photon echo regime was of the order of 40 ps, whereas when measured with the help of the stimulated photon echo generated in the single–photon mode, the value was found not to exceed 600 fs.