Conductive preferential paths of hot carriers in amorphous phase-change materials

We study charge transport properties of amorphous phase-change materials (PCM) using a set of balance equations applied to a three-dimensional random network of sites. In the context of trap- limited conduction, model results are checked against experimental data on PCM devices near the limits of scaling (10nm), explaining the main features of the current-voltage characteristics. The stochastic nature of the network also allows us to investigate the statistical variability of the sub- threshold PCM operation. Simulations of batches of similar samples show a standard deviation for the threshold condition of the order of few percent for the threshold voltage and of ten percent for the threshold current. The analysis of the network at the microscopic level near threshold reveals the formation of high-current paths, connecting the two contacts of the device through network nodes hosting the hottest carriers