Controlled synthesis of 2D van der Waals ferromagnetic 1T-CrTe2 grown by chemical vapor deposition

In this study, we report the controllable growth of two-dimensional (2D) van der Waal (vdW) magnet, chromium ditelluride (CrTe2), on a Si (100) substrate using chemical vapor deposition (CVD) technique. Our approach includes the growth of multiple single-crystal islands of CrTe2, followed by the merging of single-crystalline domains to form atomically thin films. We investigate the effect of the growth temperature (TG) and source-substrate distance (dSS) on the formation of a single-crystalline island to a large-scale, continuous film. We study surface morphology and microstructural properties of the thin film using x-ray diffraction and atomic force microscopy technique. X-ray photoelectron spectroscopy study determines the chemical composition and the oxidation states of CrTe2. Furthermore, high-resolution scanning tunnelling microscopy reveals that the surface of CVD-grown CrTe2 exhibits one unit cell steps (∼6.19 Å) with hexagonally arranged Te atoms and an in-plane lattice constant of approximately ∼3.85 Å. Raman spectroscopy shows no signs of oxidation, indicating that the CrTe2 surface is robust against air exposure. Besides excellent ambient stability, magnetic measurements show that the samples exhibit ferromagnetic order with a Curie temperature (Tc) of up to 172 K. Notably, in thinner films, Tc increases to 184 K. Our work provides a detailed growth model for achieving flat, wide-area, and large-scale synthesis of 2D vdWs ferromagnetic CrTe2.