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Theses

Caractérisation électrique et optoélectronique de nouveaux matériaux et composants photovoltaïques à partir de techniques AFM

Abstract : This thesis focuses on the characterisation of electrical properties of photovoltaic devices by using two scanning probe techniques: conductive atomic force microscopy (c-AFM) and Kelvin probe force microscopy (KPFM). It starts with a study on crystalline silicon (c-Si), and in particular the influence of surface states on the KPFM measurement. The latter was performed in the dark and under light to extract the surface photovoltage (SPV). This study was completed by numerical simulations that allow to extract surface state densities. A second study was focused on nanowire PV devices. These were PIN radial junctions based on hydrogenated amorphous silicon deposited on highly doped c-Si nanowires. We have shown that on nanowire devices that are covered with ITO,SPV measurements could mirror the value of open-circuit voltage (Voc), while the same measurements performed on single nanowires without ITO top coverage are strongly affected by the shadowing of the AFM tip and by the surface states of the amorphous silicon layer. Finally, we were interested in passivating contacts for c-Si solar cells and analysed poly-Si/SiOx/c-Si structures. When the SiOx interlayer is absent, the KPFM scans exhibit very homogeneous surface potential while numerous areas (with diameter less than 1 micron) of lower surface potential are revealed, when the SiOx buffer layer is introduced. These results seem compatible with the presence of nanometric structural inhomogeneities (pinholes) in the SiOx layer that were revealed by other studies.
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https://tel.archives-ouvertes.fr/tel-02967791
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Submitted on : Thursday, October 15, 2020 - 10:51:14 AM
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  • HAL Id : tel-02967791, version 1

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Clément Marchat. Caractérisation électrique et optoélectronique de nouveaux matériaux et composants photovoltaïques à partir de techniques AFM. Micro et nanotechnologies/Microélectronique. Université Paris-Saclay, 2020. Français. ⟨NNT : 2020UPASS094⟩. ⟨tel-02967791⟩

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