Observation of Si 2p Core‐Level Shift in Si/High‐κ Dielectric Interfaces Containing a Negative Charge

Negative static charge and induced internal electric field have often been observed in the interfaces between silicon and high‐κ dielectrics, for example Al2O3 and HfO2. The electric field provides either beneficial (e.g., field‐effect passivation) or harmful (e.g., voltage instability) effect depending on the application. Different intrinsic and extrinsic defects in the dielectric film and interface have been suggested to cause the static charge but this issue is still unresolved. Here spectroscopic evidence is presented for a structural change in the interfaces where static charge is present. The observed correlation between the Si core‐level shift and static negative charge reveals the role of Si bonding environment modification in the SiO2 phase. The result is in good agreement with recent theoretical models, which relate the static charge formation to interfacial atomic transformations together with the resulting acceptor doping of SiO2

Increased surface recombination in crystalline silicon under light soaking due to Cu contamination

avaa käsikirjoitus, kun julkaistuLight-induced degradation (LID) can occur in crystalline silicon (Si) due to increased recombination in the bulk or at the surfaces. As an example, copper (Cu) is a contaminant that reportedly causes LID in the bulk of Si under illumination. In this article, we show that Cu contamination can also increase recombination at the surface under illumination using surface saturation current density (J 0) analysis. More specifically, in the presence of Cu we observed that J 0 increased from 14 fA/cm 2 to 330 fA/cm 2 in SiO 2 passivated Float Zone (FZ) Si, and from 11 fA/cm 2 to 200 fA/cm 2 in corresponding Czochralski (Cz) Si after illumination under an LED lamp (0.6 Suns, 80 °C). In reference samples without Cu contamination, the J 0 was unaffected. These results demonstrate that a significant increase in surface recombination is possible without the presence of hydrogen. Furthermore, hydrogen was not seen to affect the Cu-induced surface degradation as similar experiments made with hydrogenated silicon nitride (SiN x:H) did not show further increase in J 0. However, the timescale of the observed degradation was relatively fast (hours) indicating that Cu-induced surface degradation is a separate phenomenon from the earlier reported surface-related degradation.Peer reviewe