Quantification of hydrogen in nanostructured hydrogenated passivating contacts for silicon photovoltaics combining SIMS-APT-TEM: A multiscale correlative approach

• Published in: Applied surface science 2021-07, Vol.555, p.149650, Article 149650
• Main Authors: Pal, Soupitak, Barrirero, Jenifer, Lehmann, Mario, Jeangros, Quentin, Valle, Nathalie, Haug, Franz-Josef, Hessler-Wyser, Aïcha, Shyam Kumar, C.N., Mücklich, Frank, Wirtz, Tom, Eswara, Santhana
• Format: Article
• Language: English
• Subjects: Atom probe tomography (APT); c-Si-solar cell; Correlative microscopy; Secondary ion mass spectrometry (SIMS); Transmission electron microscopy (TEM)
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.149650

[Display omitted] •H and D quantification is performed in a nanometer scale thin layer.•Background contribution in APT concentration profile is estimated from SIMS data.•A new correlative method has been proposed to quantify H, D using SIMS and APT. Multiscale characterization of the hydrogenation process of silicon solar cell contacts based on c-Si/SiOx/nc-SiCx(p) has been performed by combining dynamic secondary ion mass-spectrometry (D-SIMS), atom probe tomography (APT), and transmission electron microscopy (TEM). These contacts are formed by high-temperature firing, which triggers the crystallization of SiCx, followed by a hydrogenation process to passivate remaining interfacial defects. Due to the difficulty of characterizing hydrogen at the nm-scale, the exact hydrogenation mechanisms have remained elusive. Using a correlative TEM-SIMS-APT analysis, we are able to locate hydrogen trap sites and quantify the hydrogen content. Deuterium (D), a heavier isotope of hydrogen, is used to distinguish hydrogen introduced during hydrogenation from its background signal. D-SIMS is used, due to its high sensitivity, to get an accurate deuterium-to-hydrogen ratio, which is then used to correct deuterium profiles extracted from APT reconstructions. This new methodology to quantify the concentration of trapped hydrogen in nm-scale structures sheds new insights on hydrogen distribution in technologically important photovoltaic materials.