Optical Properties\nof Nanoscale-Thick 2H and 1T′\nMoTe<sub>2</sub> Films via Spectroscopic Ellipsometry: Implications\nfor Optoelectronic Devices

MoTe<sub>2</sub>, a two-dimensional (2D) transition-metal\ndichalcogenide,\nhas recently gained significant attention due to its unique optical\nand electronic properties. In this research paper, we present the\ntransition of the 2H to 1T′ phase of MoTe<sub>2</sub> films\nby controlled growth using molecular beam epitaxy. Raman spectroscopy\nconfirms the growth of the 2H and 1T′ phases of MoTe<sub>2</sub>. Then, we extensively study the optical properties of the 2H and\n1T′ phases having variable nanodimensional thicknesses of MoTe<sub>2</sub> films using spectroscopic ellipsometry (SE). SE is a powerful\ntechnique for characterizing thin films, providing valuable information\nabout their optical properties, such as refractive index and thickness.\nFurther, the optical band gaps acquired by experimental methods are\ncompared and analyzed with the first-principles electronic band structure\ncalculations. By investigating the optical behavior of MoTe<sub>2</sub> films, we aim to gain insights into their phase-dependent optical\nproperties, which can have significant implications for optoelectronic\ndevice applications.