Fourier-Transform Infrared Spectroscopy of MoTe₂ Thin Films

Molybdenum ditelluride (MoTe2), a member of the transition metal dichalcogenide family, holds significant promise in optoelectronic applications. To harness its full potential, it is imperative to understand its fundamental optical properties, including refractive indices. Herein, measurements of the transmittance and reflectance spectra of thin MoTe2 layers are conducted featuring hexagonal and monoclinic structures across the far-infrared (IR) and mid-IR spectral regions. These spectra are fitted, allowing to extract the complex refractive index and optical conductance. In the semiconducting hexagonal phase, both the conductance and extinction coefficient remain negligible below 3000 cm(-1) and increase at higher energies. Conversely, the monoclinic phase exhibits a conductance peak in the far-IR region and a continuous increase from 1000 to 6000 cm(-1). The findings are compared with existing theoretical and experimental results to provide further insights into MoTe2's optical behavior.