www Group


Origin and distribution of charge carriers in LaAlO3-SrTiO3 oxide heterostructures in the high carrier density limit, Sumanta Mukherjee, Banabir Pal, Debraj Choudhury, Indranil Sarkar, Wolfgang Drube, Mihaela Gorgoi, Olof Karis, H. Takagi, Jobu Matsuno, and D. D. Sarma, Phys. Rev. B 93, 245124, 2016.

Using hard x-ray photoelectron spectroscopy with variable photon energy (2-8 keV), we address the distribution of charge carriers in the prototypical LaAlO3 (LAO) and SrTiO3 (STO) oxide heterostructures with high carrier densities (1017 cm-2). Our results demonstrate the presence of two distinct charge distributions in this system: one tied to the interface with a ∼ 1-nm width and ∼ 2–5×1014 – cm-2 carrier concentration, while the other appears distributed nearly homogeneously through the bulk of STO corresponding to a much larger carrier contribution. Our results also establish bimodal oxygen vacancies, namely on top of LAO and throughout STO, quantitatively establishing these as the origin of the observed bimodal depth distribution of charge carriers in these highly doped sample.