Optical and electrical properties of SnSe2

The optical constants n and κ of crystalline C6, n-type SnSe 2 , at 290 and 77 °K, have been measured over the photon energy range 0·05-3·7 ev. An analysis of the absorption measurements indicates that the intrinsic SnSe 2 absorption edge (at 77 °K) arises from forbidden indirect transitions across energy gaps of less than or equal to 1·03 and 1·30 ev, and allowed direct transitions across an energy gap of 1·97 ev; the direct transitions give rise to an inflexion in the spectral distribution of 2, the imaginary part of the dielectric constant. The crystal birefringence Δ (at a wavelength of 1 μm) has been determined, and the electrical conductivity E perpendicular c and lattice parameter a 0 measured over the temperature range 77-290 °K. The properties of SnSe 2 are compared with those of other isostructural IV-VI compounds.