Figure 4
Temperature dependence of switching and transport.
(a) Measured I-V curves for bipolar reset at variable temperatures, showing that both the reset voltage and current decrease at increasing T. The inset shows the measured reset power as a function of ambient temperature T0: the linear fitting allows to extract the thermal resistance Rth = 2.7 KμW−1 and the reset temperature Treset = 460 K. (b) Arrhenius plot of resistance for the bipolar reset states obtained either starting from the PR state (amorphous phase) or from the set state (crystalline phase). The Arrhenius plot of the PR state is also shown for reference. The activation energy EC of the bipolar reset state depends on the previous state because regions of amorphous or crystalline phase remain in GST after bipolar reset. (c,d,e) Band diagrams for the PR state, the bipolar reset state obtained from a PR state and the bipolar reset state obtained from the set state, respectively. Transport in the PR state is controlled by PF emission over an energy barrier EC, while the tunneling barrier controls R for bipolar reset states. However, depending on the residual amorphous (d) or crystalline phase (e) in GST, different values of EC are obtained.
