Contrasted Behaviour of an Electron Gas in MgO, Al ₂ O ₃ and SiO ₂

Abstract

We report on the observation, by use of a sub-picosecond time-resolved phase-sensitive technique, of an electron gas pumped by an intense femtosecond laser pulse into the conduction band of three different wide-band-gap oxides. The free-carriers lifetime is measured to be two orders of magnitude longer in MgO and in Al2O3 than in SiO2.