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Sijie Yang1 Ying Qin1 Bin Chen1 V. Ongun Özçelik2 Claire E. White2 Yuxia Shen1 Shengxue Yang3 Sefaattin Tongay1

1, Arizona State University, Tempe, Arizona, United States
2, Princeton University, Princeton, New Jersey, United States
3, Beihang University, Beijing, , China

Abstract:
Recent studies have shown that tellurium based 2D crystals undergo dramatic structural, physical, and chemical changes under ambient conditions. This not only adversely impacts their much desired properties, but also is a roadblock for their applications. Here, we introduce diazonium molecule functionalization based surface engineering route that greatly enhances their environmental stability without sacrificing their much desired properties. Spectroscopy and microscopy results show that diazonium groups significantly slow down the surface reactions, and consequently gallium telluride (GaTe), zirconium telluride (ZrTe3) and molybdenum ditelluride (MoTe2) gain strong resistance to surface transformation in air or when immersed under water. Density functional theory calculations show functionalizing molecules reduces surface reactivity of Te-containing 2D surfaces by chemical binding followed by electron withdrawal process. While pristine surfaces structurally decompose due to strong reactivity of Te surface atoms, passivated functionalized surfaces retain their structural anisotropy, optical band gap, and emission characteristics as evidenced by our conductive AFM, PL and absorption spectroscopy measurements. Overall, our findings offer an effective method to increase the stability of these environmentally sensitive materials without impacting much of their physical properties.
Keywords: 2D materials, environmental stability, chemical functionalization, spectroscopy

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