Quantum-size effects in hafnium-oxide resistive switching

Discrete changes of conductance of the order of G(0) = 2e(2)/h reported during the unipolar reset transitions of Pt/HfO2/Pt structures are interpreted as the signature of atomic-size variations of the conducting filament (CF) nanostructure. Our results suggest that the reset occurs in two phases: a progressive narrowing of the CF to the limit of a quantum wire (QW) followed by the opening of a spatial gap that exponentially reduces the CF transmission. First principles calculations show that oxygen vacancy paths in HfO2 with single-to few-atom diameters behave as QWs and are capable of carrying current with G(0) conductance. (C) 2013 AIP Publishing LLC.