Characterization of oxygen impurity in silicon nitride storage layer: A first-principles investigation

Abstract

In this paper, based on first‐principles calculations, we have carried out a comprehensive study of substitutional oxygen defects in hexagonal silicon nitride (β‐Si3N4). First of all, it is found that substitutional oxygens tend to form clusters at three different sites due to the intensive attractive interaction. By analyzing modified Bader charge and trap energy, we next discuss retention characteristic of the three clusters. The results manifest that all of the clusters are amphoteric defects with the ability to trap both electrons and holes. Moreover, every cluster is more powerful to trap holes, which indicates that oxygen clusters have a higher stability to hold holes than electrons. With regard to endurance characteristic, our studies reveal that the three clusters present differences after program/erase cycles, and then we explore the mechanism of endurance degeneration by nudged elastic band method (NEB). Taking full account of retention and endurance, we deem holes rather than electrons to be optimal to act as operational charge carriers for oxygen defects in Si3N4‐based charge trapping memories.

Defective [Bi2O2]2+ Layers Exhibiting Ultrabroad Near‐Infrared Luminescence

“…The Bader charge estimates the nearbyc harges of an atom by calculating the charges that are enclosed within the Bader volume. [33] Figure 4s (Figure 4). This can be viewed as the occurrence of subvalent Bi in an undercoordinated geometry.…”

“… was confirmed to be the most stable oxygen vacancy by calculating the formation energies of the five systems containing oxygen vacancies (Table S2 in the Supporting Information); this is consistent with experimental results. The Bader charge estimates the nearby charges of an atom by calculating the charges that are enclosed within the Bader volume . Figure shows the amount of charges of all Bi atoms in Bi 2 SrTa 2 O 9 , with serial numbers (nos.…”

Research on c-HfO2 (0 0 1)/α-Al2O3 (1 -1 0 2) interface in CTM devices based on first principle theory

“…51 While, the modified Bader charge, 51 which can be obtained by the subtraction of atom's Bader charge in charged state (+/-) and neutral state, is a good way to obtain the deeper insight into the localization of the written charges. It is noted that there are three basic states during a P/E cycle: neutral state, charged state, after-erased state.…”