SnS ve SnSe?nin optik özellikleri

ABSTRACT OPTICAL PROPERTIES OF SnS and SnSe GÖNÜL (ARPA) Beşire M.S. in Engineering of Physics Supervisor: Assoc. Prof. Dr. İ.Engin TÜRE February 1991, 46 pages The optical transmission in the layered semiconductors of SnS and SnSe has been studied in the wavelength range of 200-1100 nm for the polarised light of £||a and E lib, where a and b are the crystallographic axes within the cleavage plane. Indirect bandgaps of 1.24 and 1.17 eV for SnS and 0.74 and 0.8 eV for SnSe have been found for the two directions of the polarisations Ella and Glib respectively. In the layered compound of SnSe, two indirect transitions (E... and E±2) were ] Identified as* E^l.14 ± 0.01 eV and E±2 = 1.26±0;01 eV for £ lla polarisation and E±1 = 1.12 + 0.01 eV and E±2 = 1.22 ± 0.01 eV for 6 lib polarisation. It was found that the phonon assisted transitions in SnS required the participation of two phonons with energies of 0.03 eV and 0.075 eV for Ella polarisation and 0.05 eV and 0.15 for £|fb polarisation. The K < K, relation was found to be valid in SnSe whereas K > K, a b a b relation in SnS for the whole range of energies of incident light. The compounds of SnS and SnSe were found to be strongly anisotropic from the optical measurements of these compounds. Keywords: Layered semiconductors, cleavage plane, optical transmission, absorption coefficient. iii