Mi. Alonso et al., Optical functions and electronic structure of CuInSe2, CuGaSe2, CuInS2, and CuGaS2 - art. no. 075203, PHYS REV B, 6307(7), 2001, pp. 5203
We report on the complex dielectric tensor components of four chalcopyrite
semiconductors in an optical energy range (1.4-5.2 eV, from 0.9 eV for CuIn
Se2) determined at room temperature by spectroscopic ellipsometry. Our resu
lts were obtained on single crystals of CuInSe2, CuGaSe2, CuInS2, and CuOaS
(2). Values of refractive indices n, extinction coefficients k, and normal-
incidence reflectivity R in the two different polarizations are given and c
ompared with earlier data where available. Wt: analyze in detail the struct
ures of the dielectric function observed in the studied energy region. Crit
ical-point parameters of electronic transitions are obtained from a fitting
of numerically calculated second-derivative spectra d(2)epsilon(omega)/d o
mega (2). Experimental energies and polarizations are discussed on the basi
s of published band-structure calculations.