Interfacial charge modification between SiO2 and silicon

S. Aronowitz*, H. P. Zappe, Chen-Ming Hu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


A positive flatband voltage shift, ΔVfb ≅+0.4 V, with respect to unimplanted portions of the same wafer, was obtained when calcium (1×1013 cm-2) was implanted into 87 nm of thermally grown oxide on an n-type 〈100〉 substrate and annealed. Calcium acts as a low-efficiency n-type dopant in silicon (<0.1% activated) which eliminates the possibility of calcium interactions in the substrate causing the flatband behavior. Calcium profiles after a 1100°C anneal show considerable loss from the oxide but also indicate occurrence of stable sites in the SiO2 region near the oxide-silicon interface. Theoretical calculations on a model SiO2 structure predict an effective negative charge at the Si/SiO2 interface due to calcium incorporation in agreement with the general behavior observed experimentally; moreover, the calculations predict that aluminum and strontium will behave in a similar fashion to calcium when implanted into SiO2 while boron will not.

Original languageEnglish
Pages (from-to)1317-1319
Number of pages3
JournalApplied Physics Letters
Issue number14
StatePublished - 1 Dec 1989


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