Improved switching reliability achieved in HfOx based RRAM with mountain-like surface-graphited carbon layer

In this work, we demonstrated an effective method to improve the switching reliability of HfOx based RRAM device by inserting mountain-like surface-graphited carbon (MSGC) layer. The MSGC layer was fabricated through thermal annealing of amorphous carbon (a-C) film with high sp(2) proportion (49.7%) under 500 degrees C on Pt substrate, whose characteristics were validated by XPS and Raman spectrums. The local electric-field (LEF) was enhanced around the nanoscale tips of MSGC layer due to large surface curvature, which leads to simplified CFs and localization of resistive switching region. It takes responsibility to the reduction of high/low resistance states (HRS/LRS) fluctuation from 173.8%/64.9% to 23.6%/6.5%, respectively. In addition, the resulting RRAM devices exhibited fast switching speed (<65 ns), good retention (>10(4) s at 85 degrees C) and low cycling degradation. This method could be promising to develop reliable and repeatable high-performance RRAM for practical applications. (C) 2018 Elsevier B.V. All rights reserved.