%0 Journal Article
%A Gunkel, F.
%A Hoffmann-Eifert, S.
%A Heinen, R. A.
%A Christensen, D. V.
%A Chen, Y. Z.
%A Pryds, N.
%A Waser, R.
%A Dittmann, R.
%T Thermodynamic Ground States of Complex Oxide Heterointerfaces
%J ACS applied materials & interfaces
%V 9
%N 1
%@ 1944-8252
%C Washington, DC
%I Soc.
%M FZJ-2017-00566
%P 1086 - 1092
%D 2017
%X The formation mechanism of 2-dimensional electron gases (2DEGs) at heterointerfaces between nominally insulating oxides is addressed with a thermodynamical approach. We provide a comprehensive analysis of the thermodynamic ground states of various 2DEG systems directly probed in high temperature equilibrium conductivity measurements. We unambiguously identify two distinct classes of oxide heterostructures: For epitaxial perovskite/perovskite heterointerfaces (LaAlO3/SrTiO3, NdGaO3/SrTiO3, and (La,Sr)(Al,Ta)O3/SrTiO3), we find the 2DEG formation being based on charge transfer into the interface, stabilized by the electric field in the space charge region. In contrast, for amorphous LaAlO3/SrTiO3 and epitaxial γ-Al2O3/SrTiO3 heterostructures, the 2DEG formation mainly relies on the formation and accumulation of oxygen vacancies. This class of 2DEG structures exhibits an unstable interface reconstruction associated with a quenched nonequilibrium state.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000392037400124
%R 10.1021/acsami.6b12706
%U https://juser.fz-juelich.de/record/826338