Study of Intermediate States of Ge-Rich GeSbTe Phase Change Memories by Impedance Spectroscopy

We propose a first investigation of intermediate resistance states of Ge-rich GST (GGST) PCMs by impedance spectroscopy. We highlight that all states present resistive and capacitive components. When switching the memory from the RESET to the SET state the resistance decreases continuously from a low resistance state to a high resistance state while we observe the opposite behavior for the capacitance values. Based on these results, we propose to redefine a state by considering not only the resistance but also the capacitance of the device.