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DS: Fachverband Dünne Schichten
DS 2: Thin Film Characterisation I: Structure Analysis and Composition
DS 2.10: Vortrag
Montag, 16. März 2015, 12:00–12:15, H 0111
Cu-poor/Cu-rich transition of co-evaporated CuInSe2: Na prevents annihilation of planar defects — •Helena Stange1,2, Stephan Brunken2, Humberto Rodriguez-Alvarez2, Dieter Greiner2, Christian Alexander Kaufmann2, Anja Scheu2, Jakob Lauche2, Norbert Schäfer2, Daniel Abou-Ras2, and Roland Mainz2 — 1TU Berlin, Institut für Werkstoffwissenschaften — 2Helmholtz-Zentrum-Berlin für Energie und Materialien
Highest efficiencies of Cu(In,Ga)Se2 solar cells have been achieved with absorbers deposited by a 3-stage-based co-evaporation. The Cu-poor/Cu-rich transition during the growth process and the presence of small amounts of Na and K are known to be favorable for solar cell performance. We investigate the influence of Na on the structural evolution of CuInSe2 by interrupting the growth process at overall Cu-poor and Cu-rich film compositions. CuInSe2 layers without and with NaF precursor are prepared at growth temperatures below 400°C and analyzed by XRD, XRF, EDX and GDOES. For the samples without NaF a XRD signal characteristic for planar defects are observed only for the Cu-poor samples, while for the Cu-rich samples the signal vanishes. In contrast, for the Na-containing absorbers the characteristic signal are present also for the Cu-rich samples. For Cu(In,Ga)Se2 layers without NaF precursor, real-time XRD shows annihilation of planar defects coinciding with the Cu-poor/Cu-rich transition. We conclude that the presence of Na during growth impedes annihilation of planar defects during the Cu-poor/Cu-rich transition in CuInSe2 at low growth temperatures.