Metastability of Negatively Charged Hydroxyl-E' Centers and their Potential Role in Positive Bias Temperature Instabilities

Abstract

Oxide defects are well known to negatively impact the performance of modern electronics by introducing device reliability degrading phenomena due to their ability to trap charges from the substrate during operation. The hydroxyl-E' center gained considerable attention in the recent past because of the close vicinity of its electron and hole charge transition levels to the band edges of the Si substrate. Here, we employ density functional theory to statistically analyze different hydroxyl-E' center configurations in amorphous SiO2. We identify two negatively charged defect states that are significantly lower in energy than previously discovered configurations and further show that the hydroxyl-E' center is a suitable candidate for a three-state defect model involving electron capturing processes by calculating thermal barriers between different configurations and corresponding charge transition levels. The discovered minimum energy configurations introduce electron trap levels far below the conduction band maximum of Si and SiC substrates, which might explain the experimentally observed mitigated positive temperature bias instability effect in Si/SiO2 systems compared to its negative counterpart.