Light and Elevated Temperature Induced Degradation in Gallium-Doped Silicon: A Complete Parametric Description

Despite extensive research on light and elevated temperature induced degradation (LeTID), a complete quantitative description of all relevant subprocesses is still lacking. In particular, the phenomenon of temporary recovery, which opposes the degradation transition, is poorly understood. In this study, we treat gallium-doped Czochralski silicon wafers at varying temperatures and minority charge carrier densities, measuring the resulting changes in effective lifetime. By studying temporary recovery in isolation from degradation and regeneration, we find that the rate of temporary recovery increases as temperature decreases. This is quantified by a negative activation energy of E(a)BA = - 0.6 eV. This reversed Arrhenius behavior imposes restrictions on the reaction scheme, suggesting that temporary recovery is a multi-step process involving at least two distinct subreactions. The dependence of temporary recovery on the minority charge carrier density was found to follow a power law with an exponent around . For degradation and regeneration, we derive activation energies close to . This similarity of the temperature dependence is consistent with a recently proposed atomistic model, where both degradation and regeneration occur by atomic hydrogen binding to another complex.
In total, we have provided all kinetic parameters required for describing LeTID in gallium-doped silicon with the well-known three-state model. Our findings thereby not only enhance the understanding of the underlying processes involved in LeTID, but also enable the precise modelling of the degradation rate and extent. These results lay the groundwork for complex outdoor yield models that incorporate weather data.