Highly uniform current distributions of high resistance state (HRS) and low resistance state (LRS), low 0.6 pJ switching energy, fast 30 ns switching speed, and good 10(6) cycling endurance are achieved in Ni/GeOx/Ta2O5-yNy/TaN resistive random access memory (RRAM) devices. Such good performance is attributed to nitrogen-related acceptor level in Ta2O5-yNy for better hopping conduction, which leads to forming-free resistive switching and low self-compliance switching currents. (C) 2012 Elsevier Ltd. All rights reserved.