The elasticity method
A new approach to determine recombination parameters from injection dependent carrier lifetimes of silicon wafers
Abstract
The elasticity E of a function f(x) is a mathematical operator, which can be understood as the slope of the function plotted in a log-log-plot. We analyze the elasticity E(τ −1(Δn + Ndop)) of injection-dependent lifetime measurements τ(Δn + Ndop) as a function of the majority carrier density Δn + Ndop. The value of the elasticity provides information on the recombination mechanism in the respective injection range. For example, at injection levels where E = 1, surface recombination characterized by a surface recombination current density J0 is limiting the overall recombination. Furthermore, Shockley-Read-Hall (SRH) recombination via a deep-level impurity state within the silicon bulk always leads to E(τSRH(Δn + Ndop)) > 0 and for Δn approaching zero, the elasticity exactly equals the ratio of capture time constants Q and hence provides an alternative way for its determination within a narrow injection range. Two different cases are studied experimentally: (i) Very low J0 values (1 fA/cm2) are analyzed on silicon wafers symmetrically passivated with polycrystalline silicon layers on ultrathin silicon oxide, where the analysis of the injection-dependent lifetime curves is performed in the elasticity range (1.0 ± 0.1). (ii) Two different types of light-induced bulk defects, namely the boron-oxygen center (BO) and the light- and elevated-temperature-induced degradation (LeTID) defect are investigated. The extracted Q values show excellent agreement with those values determined from fitting the SRH equation to the complete τ(Δn) curves.
Details
- Organisation(s)
-
Institute of Solid State Physics
Solar Energy Section
- External Organisation(s)
-
Institute for Solar Energy Research (ISFH)
- Type
- Article
- Journal
- Solar Energy Materials and Solar Cells
- Volume
- 292
- ISSN
- 0927-0248
- Publication date
- 15.10.2025
- Publication status
- Published
- Peer reviewed
- Yes
- ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films
- Sustainable Development Goals
- SDG 7 - Affordable and Clean Energy
- Electronic version(s)
-
https://doi.org/10.1016/j.solmat.2025.113823 (Access:
Closed
)
