Lanthanum and Lanthanum Silicide Contacts on N-Type Silicon

In this letter, we investigate contacts of a low work function rare-earth metal, La, and its silicides on n-Si. LaSi
_x
/n
^-
-Si contacts show low Schottky barrier height (φ
_b
) of around 0.25-0.4 eV and promisingly low contact resistivity (ρ
_c
) on moderately doped n
⁺
-Si. However, on highly doped n
⁺⁺
-Si, we find Pc of LaSi
_x
near one order higher than the TiSi
_x
control. This experiment indicates that low φ
_b
does not guarantee low Pc on highly doped substrates. We further discuss reasons behind this phenomenon.