Optical properties of CuIn1−xGaxSe2 quaternary alloys for solar-energy conversion

• Published in: Semiconductor science and technology 2009-01, Vol.24 (1), p.015014-015014 (8)
• Main Authors: Theodoropoulou, S, Papadimitriou, D, Anestou, K, Cobet, Ch, Esser, N
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Other semiconductors; Physics
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/0268-1242/24/1/015014

The optical properties of CuIn1-xGaxSe2 epitaxial single-crystal layers were determined by spectroscopic ellipsometry (SE) and complementary photoreflectance spectroscopy (PR) in dependence of composition. Accurate values of refractive index n and extinction coefficient kappa and values of the fundamental and higher band-gap energies of quaternary selenides were obtained for six different Ga concentrations: x = 0.0,0.1,0.2,0.5,0.5,0.82. In addition, for CuIn1-xGaxSe2 with x = 0.08 and 0.55, variable-angle ellipsometric measurements were performed. Only a very small contribution of the extraordinary component to the measured effective dielectric function was found, which implies that, in chalcopyrite single-crystal layers, the extraordinary component cannot be separated by altering the angle of incidence.