TMDs are noted by MX2, in which M is a transition metal atom and X is a chalcogen atom and can be synthesized as monolayers, bilayers or few-layers. We are interested in mapping the dielectric functions of multilayer films of various TMDs. This will enable us to gather insights on their band structure and to deduce their potential as candidates to produce optoelectronic devices. As an example, we show  the optical properties of monolayer and bilayer MoS2 films, which we obtained recently.  

We are interested in studying the behavior of phonons in semiconductors via their dielectric functions. We use ellipsometry and FTIR to extend the spectral range down to ~10 meV.  By combining these two techniques, we can obtain the dielectric functions of materials in the far-IR regions where their phonons influence the dielectric functions.  As an example, we show how the phonon features influence the dielectric functions of HgCdTe alloys.