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Daniel Rehn1 Yao Li1 Eric Pop1 Evan Reed1

1, Stanford University, Stanford, California, United States

In this work, we discuss theoretical predictions for the amount of energy required to drive a structural phase transformation in two-dimensional materials via electrostatic gating. Structural phase-change materials are of great importance for their applications in energy and information storage devices. Typically, thermally driven structural phase transitions are employed in phase-change memory to achieve lower programming voltages and potentially lower energy consumption than mainstream nonvolatile memory technologies. However, the energy consumption and waste heat generated by such thermal mechanisms is often not optimized, and could present a limiting factor to widespread use. The potential for electrostatically driven structural phase transitions has recently been predicted and subsequently experimentally reported in some two-dimensional materials, providing a novel and athermal mechanism to dynamically control the properties of the materials in a nonvolatile fashion while achieving potentially lower energy consumption. In this work, we employ DFT-based calculations to make the first theoretical comparison of energy consumption required to drive a phase transition for the thermally-driven and electrostatically-driven mechanisms. Determining theoretical limits in monolayer MoTe2 and thin films of Ge2Sb2Te5, we find that the energy consumption per unit volume of the electrostatically driven phase transition in monolayer MoTe2 at room temperature is at most 9% of the adiabatic lower limit of the thermally driven phase transition in Ge2Sb2Te5. Furthermore, experimentally reported energy consumption of Ge2Sb2Te5 is 100–10,000 times larger than the adiabatic lower limit, leaving the possibility for energy consumption in monolayer MoTe2-based devices to be several orders of magnitude smaller than Ge2Sb2Te5-based devices.

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