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Author: Andrä, Gudrun × DDC: 620 ×

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    Carrier Lifetime in Liquid-phase Crystallized Silicon on Glass
    (Amsterdam [u.a.] : Elsevier, 2016) Vetter, Michael; Gawlik, Annett; Plentz, Jonathan; Andrä, Gudrun; Ribeyron, Pierre-Jean; Cuevas, Andres; Weeber, Arthur; Ballif, Christophe; Glunz, Stefan; Poortmans, Jef; Brendel, Rolf; Aberle, Armin; Sinton, Ron; Verlinden, Pierre; Hahn, Giso
    Liquid-phase crystallized silicon on glass (LPCSG) presents a promising material to fabricate high quality silicon thin films, e.g. for solar cells and modules. Barrier layers and a doped amorphous silicon layer are deposited on the glass substrate followed by crystallization with a line focus laser beam. In this paper we introduce injection level dependent lifetime measurements generated by the quasi steady-state photoconductance decay method (QSSPC) to characterize LPCSG absorbers. This contactless method allows a determination of the LPCSG absorber quality already at an early stage of solar cell fabrication, and provides a monitoring of the absorber quality during the solar cell fabrication steps. We found minority carrier lifetimes higher than 200ns in our layers (e.g. n-type absorber with ND=2x1015cm-3) indicating a surface recombination velocity SBL<3000cm/s at the barrier layer/Si interface.
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    Large area graphene deposition on hydrophobic surfaces, flexible textiles, glass fibers, 3D structures, and adhesion of graphene layer
    (Basel : MDPI, 2019) Jia, Guobin; Plentz, Jonathan; Dellith, Jan; Dellith, Andrea; Wahyuono, Ruri Agung; Andrä, Gudrun
    Graphene and its derivatives have many superior electrical, thermal, mechanical, chemical, and structural properties, and promise for many applications. One of the issues for scalable applications is the lack of a simple, reliable method that allows the deposit of a well-ordered monolayer using low-cost graphene flakes onto target substrates with different surface properties. Another issue is the adhesion of the deposited graphene thin film, which has not been well investigated yet. Following our former finding of a double self-assembly (DSA) process for efficient deposition of a monolayer of graphene flakes (MGFs), in this work we demonstrate that the DSA process can be applied even on very challenging samples including highly hydrophobic polytetrafluoroethylene (PTFE), flexible textiles, complex 3D objects, and thin glass fibers. Additionally, we tested adhesion of the graphene flakes on the flat glass substrate by scotch tape peel test of the MGFs. The results show that the graphene flakes adhere quite well on the flat glass substrate and most of the graphene flakes stay on the glass. These findings may trigger many large-scale applications of low-cost graphene feedstocks and other 2D materials.