Melting‐Free Crystalline Polymorphic Transition in CrTe Thin Films: Potential for Phase‐Change Random Access Memory Applications

The phase‐change potential of an as‐deposited chromium telluride (CrTe) thin film is investigated by focusing on its crystalline‐to‐crystalline polymorphic transition. Transmission electron microscopy determined that the as‐deposited CrTe thin film exhibits a hexagonal crystal structure that changes to a monoclinic crystal structure upon annealing at 500 °C. This alteration of the crystal structure is accompanied by a large change in carrier concentration of around two magnitudes and a very small corresponding change in resistivity. The memory switching of a fabricated phase‐change memory device utilizing a CrTe thin film active layer demonstrates a pronounced resistance disparity between SET and RESET states compared to the resistance change upon phase change in the thin‐film case. This disparity is attributed to variations in the contact resistivity of the memory device, which are driven by changes in the carrier concentration upon the crystalline polymorphic transition. Electrical pulse measurements confirm that the resistance change is reversible and repeatable, highlighting the material's potential for phase‐change random access memory applications.