Effect of nitrogen-doped GST buffer layer on switching characteristics of conductive-bridging RAM

We demonstrate the device characteristics of W/Cu/N-GST/Al2O3/Pt conductive-bridging RAM, focusing on the nitrogen-doped Ge2Sb2Te5 buffer layer to realize non-volatile memory applications. The on/off ratio of typical Cu/Al2O3-based CBRAM was improved from 102 to 105 with the N-GST buffer layer. The switching uniformity also improved compared to that of a non-buffer layer device. The improved properties that were realized are attributed to the effects of buffer layer such as controlled Cu-ion injection, internal resistor, and Joule heating confinement during the reset process. Furthermore, to verify the effect of nitrogen on the switching properties, we compared the GST and N-GST buffer layers. We believe that doped nitrogen helped to control Cu-ion injection into the resistive switching layer, and to confine the joule heating during the reset process, enabling a high on/off ratio and improved switching uniformity.