Abstract
The effect of light- and elevated temperature-induced degradation (LeTID) can be nonpermanently reversed by charge carrier injection below the degradation temperature (commonly used degradation temperatures are above ~70 °C). In this study, we show that the rate of temporary recovery depends strongly on the excess carrier density. We observe that the order of the reaction changes from pseudo-zero to first with increasing injection. The rate decreases slightly with increasing temperature. Since the samples can go through multiple degradation/recovery cycles without distinct changes in the degradation kinetics, the experimentally accessible recovered and degraded states are interpreted as manifestations of the equilibrium concentrations of the defect responsible for LeTID at different temperatures. Based on our observations, we argue that the process underlying LeTID degradation is the dissociation of a precursor rather than an association of two or more components. In light of the relation between LeTID susceptibility and bulk hydrogen concentration, we hypothesize that the LeTID precursor dissociates into the LeTID defect and monatomic hydrogen. Numerical simulations of the coupled rate equations including hydrogen interactions well reproduce the experimental observations; according to these results, the presence of a sink for the atomic hydrogen such as dopant atoms is paramount for the LeTID degradation.
Highlights
A FTER the first description of the phenomenon later termed light- and elevated temperature-induced degradation (LeTID) [1], extensive research has been conducted on the influences determining the LeTID extent and kinetics
We investigated the temporary recovery (TR) of the LeTID defect, which occurs when charge carriers are injected around room temperature into samples that had previously been degraded under LeTID conditions
We found that the recovery rate increases strongly with increasing injection and decreases slightly with increasing temperature
Summary
A FTER the first description of the phenomenon later termed light- and elevated temperature-induced degradation (LeTID) [1], extensive research has been conducted on the influences determining the LeTID extent and kinetics. Later works showed the intriguing complexity of the influences of dark anneals (DA) on LeTID: First, detailed investigations revealed that the participation of excess carriers is not always necessary to provoke degradation and regeneration; the same cycle occurs during DA at an elevated temperature within a certain range around 175 °C [6]. Samples treated in this way—irrespective of the degradation/regeneration stage reached during DA—are susceptible to another degradation/regeneration-cycle if LeTID conditions including excess carriers are applied afterward [15]. We couple the LeTID degradation and TR reactions with the hydrogen reactions and explore the parameter range allowing for reproducing experimental observations, explicitly considering known hydrogen interactions in the temperature range of interest (i.e., change in charge states, hydrogen molecule formation and dissociation, pairing with dopant atoms, and formation of stable dimers [27])
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