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HL: Fachverband Halbleiterphysik

HL 45: HL Posters III

HL 45.16: Poster

Donnerstag, 4. April 2019, 18:30–21:00, Poster E

Electroreflectance studies of CdS buffers in CIGS solar cells: Influence of Ga content and thermal annealing on the CdS bandgap — •Nico Weber¹, Jasmin Seeger¹, Jonas Grutke¹, Wolfram Witte², Dimitrios Hariskos², Oliver Kiowski², Heinz Kalt¹, and Michael Hetterich^1,3 — ¹Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — ²Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70563 Stuttgart, Germany — ³Light Technology Institute, KIT, 76131 Karlsruhe, Germany

Cu(In,Ga)Se₂ (CIGS) has proven to be ideally suited as absorber material for high efficiency thin-film solar cells due to its excellent optical and electrical properties. In order to further improve the CIGS solar cells, a detailed understanding of the absorber–buffer interface is required. For this purpose, CIGS solar cells with the commonly used CdS buffer layer are investigated utilizing angle-resolved electroreflectance (ARER) spectroscopy. This new approach enables an accurate and destruction-free bandgap energy determination of the buffer layer despite the occurring interference effects caused by the layer stack. Therefore, ARER can provide information about possible interdiffusion processes between buffer and absorber layers. In this contribution, we employ ARER to study the impact of different gallium contents of the absorber on the bandgap energy of the buffer layer. In addition, the influence of thermal annealing on the bandgap energy of the buffer layer is investigated.