In search of a hole inversion layer in $\mathrm{Pd}/\mathrm{MoO}_{x}/\mathrm{Si}$ diodes through I- V characterization using dedicated ring-shaped test structures

Palladium (Pd) capped molybdenum-oxide (MoO
_x
) thin films deposited bye-beam evaporation on p- and n-type silicon (Si) substrates were investigated employing dedicated ring-shaped test structures. The results show diode characteristics on n-type Si with a high rectification of ~ 10
⁸
and a low leakage current of ~ 10
^-11
A and an ohmic contact on p-type Si, as expected from the reported high workfunction of MoO
_x
. Reports in the literature that an inversion layer of holes should be present at the MoO
_x
/n -Si interface were investigated via various DC electrical measurements on lateral test structures, but no indication of any significant inversion was found.