Optical properties and electronic energy-band structure of CdIn2Te4

Optical properties of a defect-chalcopyrite-type semiconductor CdIn2Te4 have been studied by optical absorption, spectroscopic ellipsometry (SE), and thermoreflectance (TR) measurements. Optical absorption measurements suggest that CdIn2Te4 is a direct-gap semiconductor having the bandgap of ∼1.22 eV at 300 K. The complex dielectric-function spectra, ɛ(E) = ɛ1(E) + iɛ2(E), measured by SE reveal distinct structures at energies of the critical points in the Brillouin zone. TR spectroscopy facilitates the precision determination of the critical point energies. By performing the band-structure calculation, such critical points are successfully assigned to specific points in the Brillouin zone.