Optical properties and electronic structure of polycrystalline Ag1−xCuxInSe2 alloys

Abstract

The dielectric function ͑͒ of polycrystalline bulk samples of the quaternary chalcopyrite semiconductors Ag 1−x Cu x InSe 2 with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 has been determined by spectroscopic ellipsometry in the energy range from 0.5 to 4.7 eV at room temperature. Accurate values of refractive indices n and extinction coefficients k representative of bulk materials are obtained from the data. The value of the main energy gap is very sensitive to the composition and varies from 1.225 to 1.009 eV as x increases ͑Cu content͒. The structures observed in ͑͒ have been analyzed by fitting the numerically differentiated experimental spectrum ͑second derivative͒ to analytical line shapes. As a result, the energies corresponding to different electronic transitions have been determined as a function of the composition, and they have been identified within the electronic band structure of chalcopyrites.

Optical constants of Cu2ZnGeS4 bulk crystals

“…Special attention was paid to the preparation of good quality "pure" surface as it was proposed by Albornoz. et al 10 to minimize non desired effects such as normal and microscopic roughness. In these conditions the real and imaginary parts of the dielectric function ͑E͒ = 1 ͑E͒ + i 2 ͑E͒ can be obtained for a homogeneous and isotropic substrate from the equation of two-phase ͑substrate-ambient͒ model…”

Spectroscopic ellipsometry study of Cu2ZnSnSe4 bulk crystals

“…The samples were polished following the procedure proposed by Albornoz et al in order to minimize the presence of oxides and roughness effects. 15 The real part e 1 (E) and the imaginary part e 2 (E) of the pseudo-dielectric functions of three different CZTSe bulk crystals, determined from ellipsometry measurements by using a two-phase model, 16 are plotted in Fig. 3(a).…”

Optical Characterization of Laser-Synthesized Anatase TiO2Nanopowders by Spectroscopic Ellipsometry and Photoluminescence Measurements

“…Therefore more proper model of the dielectric function of anatase nanopowder is applied in this study by using critical point (CP) analysis [9,10]. This model has been successfully applied to identify and evaluate the energy of the electronic transitions in different semiconducting materials [10,11].…”