An access-transistor-free resistive random access memory (RRAM) using a GST/TiO2 stack and its novel access mechanism

Novel resistive random access memory (RRAM) cell structure without an access transistor or diode is proposed and fabricated. The cell structure is comprised of both a phase change material (GeSbTe) and a bipolar resistive switching material (TiO2). The electrical properties of the proposed cell are also evaluated in order to verify the possibility of operation without an access transistor or diode. And then the cell access mechanism is proposed in order to operate our RRAM cell without an unexpected current path. By using our proposed RRAM cell structure, we expect that high density memory with the simple 4F² cross-point structured cell array can be easily fabricated by two photo lithography processes.