SKM 2021 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Poster Session IV

HL 19.1: Poster

Thursday, September 30, 2021, 13:30–16:30, P

Bandgap and Secondary Phase Analysis of (A)CIGS Solar Cell Absorber and Buffer Layers Using Electroreflectance Spectroscopy — •Michael Dao¹, Jonas Grutke¹, Wolfram Witte², Dimitrios Hariskos², 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

Thin-film solar cells based on Cu(In,Ga)Se₂ (CIGS) absorbers have established themselves as highly efficient photovoltaic devices. To further optimize their properties, the incorporation of silver (Ag) into the absorber layer (ACIGS) is currently investigated by many groups. In this contribution, the effect of Ag on the absorber bandgap energy as well as the corresponding inhomogeneous broadening is investigated by electroreflectance spectroscopy (ER) which allows a destruction-free analysis of full device structures. Additionally, angle-resolved ER (ARER) is applied to study the impact of Ag on the formation of secondary phases as well as possible interdiffusion effects at the absorber-buffer interface. Using this technique, the bandgap energies of both the buffer layer as well as secondary phases can be determined despite interference effects in the multi-layered device structure and the small thickness < 60 nm of the buffer layer.