On the volatility of oxide defects: Activation, deactivation, and transformation

Recent studies have clearly shown that oxide defects are more complicated than typically assumed in simple two-state models, which only consider a neutral and a charged state. In particular, oxide defects can be volatile, meaning that they can be deactivated and re-activated at the same site with the same properties. In addition, these defects can transform and change their properties. The details of all these processes are presently unknown and poorly characterized. Here we employ time-dependent defect spectroscopy (TDDS) to more closely study the changes occurring at the defect sites. Our findings suggest that these changes are ubiquitous and must be an essential aspect of our understanding of oxide defects. Using density-functional-theory (DFT) calculations, we propose hydrogen-defect interactions consistent with our observations. Our results suggest that standard defect characterization methods, such as the analysis of random telegraph noise (RTN), will typically only provide a snapshot of the defect landscape which is subject to change anytime during device operation.