arXiv subjects

Aïcha Hessler-Wyser

Publications and source records attributed to Aïcha Hessler-Wyser.

2 recordsLinked to original sources

arXiv2026

Single Best Fits Can Be Misleading: Resolving Common Trapping Signatures across FA--Cs Perovskites

Identifying defects responsible for non-radiative recombination in metal-halide perovskites remains challenging, with no common defect signatures established across compositions. Here, we combine fluence-dependent time-resolved photoluminescence, full Shockley--Read--Hall modelling and Bayesian posterior inference across an FA$_{1-x}$Cs$_x$PbI$_3$ compositional series. We show that trap occupation governs carrier dynamics and defect-parameter identifiability in semiconducting materials: weakly occupied states exhibit electron-capture-coefficient--trap-density degeneracies, whereas trap filling lifts them. In our perovskite systems, a non-degenerate signature $Tβ$, characterized by a strongly asymmetric $β_p/β_n$ capture-coefficient ratio, occurs across all compositions, suggesting substantial trap filling is a general feature of perovskite carrier dynamics. We further identify $Tα$ as a shared, device-performance-limiting non-radiative recombination channel, while a shallow $Tε$ signature unique to FAPbI$_3$ produces the largest steady-state non-radiative recombination rate and is consistent with the previously observed high stacking-fault density of this composition. This framework therefore provides a basis for comparing trapping signatures across different semiconducting materials at room temperature.

cond-mat.mtrl-sci↗

arXiv2019

Analysis of hydrogen distribution and migration in fired passivating contacts (FPC)

In this work, the hydrogenation mechanism of fired passivating contacts (FPC) based on c-Si/SiO$_{x}$/nc-SiC$_{x}$(p) stacks was investigated, by correlating the passivation and local re-distribution of hydrogen. Secondary ion mass spectroscopy (SIMS) depth profiling was used to assess the hydrogen (/deuterium) content. The SIMS profiles show that hydrogen almost completely effuses out of the SiC$_{x}$(p) during firing, but can be re-introduced by hydrogenation via forming gas anneal (FGA) or by release from a hydrogen containing layer such as SiN$_{x}$:H. A pile-up of H at the c-Si/SiO$_{x}$ interface was observed and identified as a key element in the FPC's passivation mechanism. Moreover, the samples hydrogenated with SiN$_{x}$:H exhibited higher H content compared to those treated by FGA, resulting in higher iV$_{OC}$ values. Further investigations revealed that the doping of the SiC$_{x}$ layer does not affect the amount of interfacial defects passivated by the hydrogenation process presented in this work. Eventually, an effect of the oxide's nature on passivation quality is evidenced. iV$_{OC}$ values of up to 706 mV and 720 mV were reached with FPC test structures using chemical and UV-O$_{3}$ tunneling oxides, respectively, and up to 739 mV using a reference passivation sample featuring a ~25 nm thick thermal oxide.

physics.app-ph↗