posted on 2024-01-18, 09:03authored byBenjamin E. Davis, Nicholas C. Strandwitz
The effects of different
high-κ tunnel oxides on the metal–insulator–semiconductor
Schottky barrier height (ΦB) were systematically
investigated. While these high-κ interlayers have been previously
observed to affect ΦB, there has never been a clear
consensus as to why this ΦB modulation occurs. Changes
in ΦB were measured when adding 0.5 nm of seven different
high-κ oxides to n-Si/Ni contacts with a thin native silicon
oxide also present. Depending on the high-κ oxide composition
and ΦB measurement technique, increases in ΦB up to 0.4 eV and decreases up to 0.2 eV with a high-κ
introduction were measured. The results were compared to several different
hypotheses regarding the effects of tunnel oxides on ΦB. The experimental data correlated most closely with the model of
a dipole formed at the SiOx/high-κ
interface due to the difference in the oxygen areal density between
the two oxides. Knowledge of this relationship will aid in the design
of Schottky and ohmic contacts by providing criteria to predict the
effects of different oxide stacks on ΦB.