Oxidation-driven structural, chemical and electrical transformation in ZrSe2

The intrinsic air sensitivity of two-dimensional (2D) transition metal dichalcogenides (TMDs) poses a major challenge for their deployment in nanoelectronics devices. In this work, we present a comprehensive study of the oxidation-driven degradation of ZrSe 2 , revealing the time-dependent evolution of surface morphology, chemical composition, and device performance. Using a suite of experimental techniques including AFM, SEM, STM, EDX, XPS, and Raman spectroscopy, complemented by density functional theory (DFT) simulations, we track the spontaneous formation of Se-rich protrusions and nanowires resulting from oxidation. Our findings demonstrate that oxidation initiates both at defect sites and edges, leading to the formation of a native Zr oxide that promotes selenium segregation. EDX confirms Se-rich blisters and nanowires, while Raman spectroscopy reveals the loss of ZrSe 2 vibrational modes and the emergence of Se peaks over time. DFT results further explain this behaviour by showing that oxygen adsorption weakens Zr-Se bonds and facilitates Se clustering. Encapsulation with a thin e-beam evaporated ZrO 2 layer limits degradation and offers a path toward improved field-effect transistor performance under optimized conditions. This work provides new insights into the degradation pathways of ZrSe 2 and underscores the critical importance of interface engineering and environmental control for reliable 2D semiconductor devices.