Native defects in hexagonalβ-Si3N4

Abstract

A comprehensive study of single native point defects in hexagonal silicon nitride (β-Si 3 N 4 ) has been carried out based on density functional calculations of formation energies. Both nitrogen-and silicon-rich native defect centers form donor and acceptor states in the band gap of β-Si 3 N 4 , confirming their amphoteric behavior. Silicon dangling bonds resulting from structural nitrogen vacancies (V N ) are the most abundant native defects, in particular, in their acceptor state (V − N and V 3− N ). Hydrogenation promotes the appearance of Si dangling bond defects in the neutral state consistent with the observation of paramagnetic centers in the gap of amorphous silicon nitrides by electron spin resonance. This explains the utility of silicon nitride as charge trapping layer in nonvolatile memories.

From Jekyll to Hyde and Beyond: Hydrogen’s Multifaceted Role in Passivation, H-Induced Breakdown, and Charging of Amorphous Silicon Nitride

“…Solid lines mark the average over the entire ensemble together with the individual data points for the +1/0 (average 0.4 eV) and 0/−1 (average 2.9 eV) charge transition levels. In agreement with previous work, 33,38,59 H can passivate dangling bonds, removing those defects from the band gap. These defects are always the lowest-energy configuration and in essence represent a healing of the network via the removal of undercoordinated centers.…”

“…In agreement with previous work, ,, H can passivate dangling bonds, removing those defects from the band gap. These defects are always the lowest-energy configuration and in essence represent a healing of the network via the removal of undercoordinated centers.…”

“…H Incorporation in β-Si 3 N 4 . As a starting point, we briefly revisit hydrogen incorporation in the most stable crystalline phase (β-Si 3 N 4 ), which has been previously studied by Di Valentin et al and Grillo et al To facilitate the comparison with a-Si 3 N 4 , we have performed calculations with our computational setup. Full details are included in the Supporting Information, and a brief summary is given here: In β-Si 3 N 4 , hydrogen forms a negative- U ( U ≈ −0.5 eV) amphoteric defect familiar from a broad range of oxides, , most notably SiO 2 .…”

Effects of intrinsic defects and extrinsic doping on the electronic and photocatalytic properties of Ta3N5

“…2a, the interstitial N in Ta 3 N 5 is stable only in +1 and À1 charge states with the (À1/+1) transition level at 0.58 eV above the VBM, indicating it is a negative U defect. 34 Therefore, it cannot contribute to the n-type conductivity because it behaves like an acceptor under typical n-type conditions while as a donor under p-type conditions. From the DOS shown in Fig.…”

Explanation of the Charge Trapping Properties of Silicon Nitride Storage Layers for NVMs—Part II: Atomistic and Electrical Modeling

“…In this respect, it is worth pointing out that the oxygen-related defects at the SiN interfaces have been studied by means of atomistic simulations in [11]. Moreover, the hydrogen-related defects in the bulk SiN have been studied by density functional theory (DFT) in [12], whereas the properties of Si dangling bonds have been investigated in [13] and [14]. In this paper, our attention has been focused on the traps located in the bulk of the SiN film, which is justified also by the experimental results of [15], which show that the centroid of the charge trapped in the silicon-oxide-nitride-oxide-silicon (SONOS)/MANOS devices is essentially in the center of the trapping layer, thus suggesting 0018-9383/$26.00 © 2011 IEEE the important role of bulk SiN traps for the cell operation in the whole range of interest for NVM applications of the SiN thickness [16].…”