Optical Properties of Nanoscale-Thick 2H and 1T′ MoTe₂ Films via Spectroscopic Ellipsometry: Implications for Optoelectronic Devices

MoTe2, a two-dimensional (2D) transition-metal dichalcogenide, has recently gained significant attention due to its unique optical and electronic properties. In this research paper, we present the transition of the 2H to 1T′ phase of MoTe2 films by controlled growth using molecular beam epitaxy. Raman spectroscopy confirms the growth of the 2H and 1T′ phases of MoTe2. Then, we extensively study the optical properties of the 2H and 1T′ phases having variable nanodimensional thicknesses of MoTe2 films using spectroscopic ellipsometry (SE). SE is a powerful technique for characterizing thin films, providing valuable information about their optical properties, such as refractive index and thickness. Further, the optical band gaps acquired by experimental methods are compared and analyzed with the first-principles electronic band structure calculations. By investigating the optical behavior of MoTe2 films, we aim to gain insights into their phase-dependent optical properties, which can have significant implications for optoelectronic device applications.