Optical properties and electronic structures of (4CuInSe(2))(y)(CuIn5Se8)(1-y)
2006 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, no 8Article in journal (Refereed) Published
Spectroscopic ellipsometric measurements of thin polycrystalline (4CuInSe(2))(y)(CuIn5Se8)(1-y) films reveal that there are important differences in optical properties and electronic structures between alpha-phase CuInSe2 and Cu-poor CuInSe2. We report the optical functions of thin-film polycrystalline (4CuInSe(2))(y)(CuIn5Se8)(1-y) and describe how they change depending on the degree of Cu deficiency. We find a reduction in the absorption strength in the spectral region of 1-3 eV for Cu-poor CuInSe2. This reduction can be explained in terms of density of the Cu 3d states in CuInSe2. Cu-poor CuInSe2 samples show an increase in band gap due to reduced p-d interaction. We find that the reduction in the amplitudes of E-0(A,B,C) transitions at the Gamma point and E-1(A,B) transitions at the N point are due to Cu deficiency. Local density approximation calculations with a modeled on-site self-interaction correction of the absorption coefficients of Cu8In8Se16 (CuInSe2), Cu5In9Se16 (CuIn3Se5-like), and Cu2In10Se16 (CuIn5Se8) are in good agreement with those of thin-film polycrystalline CuInSe2 samples with 24.1, 15.6, and 9.1 at. % Cu, respectively.
Place, publisher, year, edition, pages
2006. Vol. 74, no 8
density-functional theory, abc2 chalcopyrite semiconductors, cu(in,ga)se-2 thin-films, spectroscopic ellipsometry, solar-cells, temperature-dependence, absorption-edge, phase-relations, surface-layer, cuinse2
IdentifiersURN: urn:nbn:se:kth:diva-15968DOI: 10.1103/PhysRevB.74.085212ISI: 000240238900045ScopusID: 2-s2.0-33748133062OAI: oai:DiVA.org:kth-15968DiVA: diva2:334010
QC 201005252010-08-052010-08-05Bibliographically approved