Impurity induced band-gap narrowing in p-type CuIn1-xGax(S,Se)(2)
2009 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 7, 2374-2379 p.Article in journal (Refereed) Published
Green's functions modelling of the impurity induced effects in p-type CuIn1-xGaxS2 and CuIn1-xGaxSe2 (x = 0.0, 0.5, and 1.0) reveals that: (i) the critical active acceptor concentration for the metal non-metal transition occurs at Nc approximate to 10(17)-10(18) cm(-3) for impurities with ionization energy of E-A approximate to 30-60 meV. (ii) For acceptor concentrations N-A>N-C, the hole gas of the metallic phase affects the band-edge energies and narrows the energy gap E-g=E-g(0)=Delta E-g. The energy shift of the valence-band maximum Delta E-v1 is roughly twice as large as the shift of the conduction-band minimum Delta E-c1. (iii) Delta E-v1 depends strongly on the non-parabolicity of the valence bands. (iv) Sulfur based compounds and Ga-rich alloys have the largest shifts of their band edges. (v) A high active acceptor concentrations of N-A = 10(20) cm(-3) implies a band-gap narrowing in the order of Delta E-g approximate to 0.2 eV, thus E-g=E-g(0)-0.2 eV, and an optical band gap of E-g(opt)approximate to E-g(0)-0.1 eV.
Place, publisher, year, edition, pages
2009. Vol. 517, no 7, 2374-2379 p.
Doping, Electronic structure, Many-particle effects, Band gap, Phase transition, CuInSe2, CuInS2
Other Engineering and Technologies not elsewhere specified
IdentifiersURN: urn:nbn:se:kth:diva-31245DOI: 10.1016/j.tsf.2008.11.009ISI: 000263847300064ScopusID: 2-s2.0-58949100308OAI: oai:DiVA.org:kth-31245DiVA: diva2:405623
QC 20110323 Symposium on Thin Film Chalcogenide Photovoltaic Materials held at the EMRS 2008 Spring Conference, Strasbourg, FRANCE, MAY 26-30, 20082011-03-232011-03-112011-03-23Bibliographically approved