Unipolar resistive switching characteristics of W/Si₃N₄/Si memory devices with doped silicon bottom electrodes

In this paper, we report the effects of two different types of dopants (n- and p-type semiconductors) on the unipolar resistive switching characteristics of a fully CMOS-compatible W/Si₃N₄/Si structure. The W/Si₃N₄/p⁺-Si device displayed a gradual reset transition, while the W/Si₃N₄/n⁺-Si device showed abrupt reset switching. The different reset switching behaviors of the devices can be explained by their different properties immediately before set switching, which were experimentally demonstrated by the statistical relationships between resistive switching parameters such as the set and reset voltages, the set and reset currents, and the resistances of the high resistance state (HRS) and low resistance state (LRS). The different reset switching properties of the devices were further evidenced by the dynamics of the conducting paths in the LRS immediately before reset switching. The W/Si₃N₄/p⁺-Si device showed superior resistive switching performance to the W/Si₃N₄/n⁺-Si one because of the gradual transition with low reset current. Finally, we demonstrated multi-level switching, which is attractive for application in high-density memory, by altering the reset voltage.