Low power ovonic threshold switching characteristics of thin GeTe₆ films using conductive atomic force microscopy

Minimizing the dimensions of the electrode could directly impact the energy-efficient threshold switching and programming characteristics of phase change memory devices. A ∼12-15 nm AFM probe-tip was employed as one of the electrodes for a systematic study of threshold switching of as-deposited amorphous GeTe₆ thin films. This configuration enables low power threshold switching with an extremely low steady state current in the on state of 6-8 nA. Analysis of over 48 different probe locations on the sample reveals a stable Ovonic threshold switching behavior at threshold voltage, V_TH of 2.4 ± 0.5 V and the off state was retained below a holding voltage, V_H of 0.6 ± 0.1 V. All these probe locations exhibit repeatable on-off transitions for more than 175 pulses at each location. Furthermore, by utilizing longer biasing voltages while scanning, a plausible nano-scale control over the phase change behavior from as-deposited amorphous to crystalline phase was studied.