Current–voltage characteristics of Ag/Nb:SrTiO3/Ag and Au/Nb:SrTiO3/Ag heterostructures

Abstract

Ag/Nb:SrTiO3(NSTO)/Ag and Au/NSTO/Ag structures were prepared and their current–voltage curves were studied in detail. The Ag/NSTO/Ag structure can demonstrate a pronounced resistive switching effect and the characteristics of its resistance change sequence as demonstrated in the I–V curves are significantly different from those of the Au/NSTO/Ag structure. Under a unipolar current, the Ag/NSTO/Ag structure translates first from a low-resistance state (LRS) to a high-resistance state (HRS) and then from the HRS to the LRS. However, the Au/NSTO/Ag structure only shows a transition from the HRS to the LRS. The phenomenon is analyzed taking into account the migration of oxygen ions and the electrochemical reaction of the Ag electrode, which lead to the formation of the Ag2O insulation layer as well as Ag conductive filaments in the Ag/NSTO/Ag structure and a change in the barrier height of the Au/NSTO interface.