Properties of innovative resistive memories studied by X‐ray and UV photoemission

Abstract

Abstract Pt/NiO‐based devices are promising candidates for the next generation of resistive random access memories (RRAMs). X‐ray (XPS) and ultraviolet (UPS) photoemission are performed to investigate the chemical and electronic properties of this stack. After resistive switching of the nickel oxide, the as‐deposited and switched areas are compared in situ . The surface of the conductive area is characterised by a higher oxygen content as well as an enhancement of Ni 3+ oxidation state, which can be related to defects such as Ni vacancies. The results are compatible with a bias‐induced diffusion of O 2− towards the anode, and a migration of Ni 2+ towards the cathode. The NiO electron affinity is estimated to be 1.6 eV by UPS in the OFF state, leading to a Pt/NiO barrier height of 3.6 eV. Copyright © 2010 John Wiley & Sons, Ltd.