Temporary Recovery of the Defect Responsible for Light- and Elevated Temperature-Induced Degradation: Insights Into the Physical Mechanisms Behind LeTID

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. Index Terms-Degradation, Defect reactions, light-and elevated temperature-induced degradation (LeTID), model, silicon defects. I. INTRODUCTION 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. Noting the

Insights into the Hydrogen‐Related Mechanism behind Defect Formation during Light‐ and Elevated‐Temperature‐Induced Degradation

“…Please note that, as we have estimated previously, [16] the density of LD (%10 11 cm À3 ) is presumably orders of magnitude lower than the detection limit of [BH] (%3 Â 10 14 cm À3 ). Therefore, a direct measurement of hydrogen-related changes caused by LD formation is very difficult and would always be influenced by other hydrogen-related reactions.…”

“…LD can be reversed into the initial state by charge carrier injection at room temperature ("temporary recovery"). [16] In the context of model 1, the temporary recovery would mean that the LP-H complex dissociates with the dissociated hydrogen-forming H 2A molecules again. To the authors' knowledge, the formation of H 2A during carrier injection at room temperature has not yet been observed.…”

“…[13][14][15] In a recent study, we presented a numerical model for the temperature-dependent hydrogen kinetics based on the current knowledge about hydrogen. [16] We suggested that the LeTID defect formation is a dissociation process with hydrogen dissociating from the LeTID precursor. As the solubility of unbound hydrogen in silicon is very low, significant dissociation-and hence degradation-only occurs if the released hydrogen is bound to other sinks, e.g., boron to form B-H pairs.…”

Influence of Dopant Elements on Degradation Phenomena in B‐ and Ga‐Doped Czochralski‐Grown Silicon

“…[ 42 ] In a previous publication, we hypothesized that during LeTID, the precursor dissociates into the LeTID defect and atomic hydrogen. [ 43 ] With the solubility of atomic hydrogen being very low, the degradation can only proceed if the released hydrogen is transferred to a sink, which could be the acceptor atoms. As shown in the previous study, [ 44 ] boron–hydrogen pairs dissociate more easily under illumination than in the dark.…”

“…Some Ga‐doped sister samples were tested for TR. [ 43 ] This was done in two different ways: 1) The temperature was kept constant at 75 °C, but the illumination conditions were switched between 1 and 0.1 sun eq. intensity.…”