Spatial density profile of electrons near the LaAlO[3]/SrTiO[3] heterointerface revealed by time-resolved photoluminescence spectroscopy

Abstract

The depth profile of the electron density near the LaAlO[3]/SrTiO[3] heterointerface has been studied by means of time-resolved photoluminescence (PL) spectroscopy. A broad blue PL band is observed at 2.9 eV, originating from the two-carrier radiative recombination of interface-induced electrons andphotoexcited holes. The PL lifetime of LaAlO[3]/SrTiO[3] heterointerface is dominated by the three-carrier Auger recombination of electrons and holes and is sensitive to electron density. We tuned the probing depth by changing the excitation photon energy and evaluated the carrier-density profile using the relation between the carrier density and the PL lifetime. Our non-contact probe method based on PL spectroscopy indicates that the carriers are confined within several nanometers in depth near the LaAlO[3]/SrTiO[3] heterostructures.