Structural and morphological evolution of MoSe2 thin films as interlayers in phase-change heterostructures

Molybdenum diselenide (MoSe2) is attracting interest as interlayer material in phase-change memories, where it can limit elemental diffusion and stabilize device operation. Here, we investigate thin MoSe2 films deposited by RF sputtering at room temperature and analyze their structural and electrical response upon thermal treatment. As-grown films crystallize into a structure compatible with the 2H phase above 250 °C, with the appearance of diffraction peaks and vibrational modes typical of MoSe2. This transition is accompanied by a densification of the films and a reorganization of the surface into compact grains, as revealed by X-ray reflectivity and microscopy. Raman spectra show the coexistence of well-defined phonon modes and disorder-related features, while electrical measurements show anomalous behavior after annealing at 300 °C, which may be attributed to morphology-related effects. Importantly, MoSe2 maintains its stoichiometry after deposition and annealing, demonstrating chemical stability. When integrated into GST225/MoSe2 heterostructures, the material preserves its integrity and withstands annealing up to 300 °C, confirming its compatibility with phase-change layers to be switched back and forth between their as-grown and crystalline states. These findings support the use of sputtered MoSe2 as a robust interlayer in next-generation phase change memory devices.