Probing the hot-electron transport properties and interface band structure of Fe/Si (001) and Fe81 C19/Si (001) Schottky diodes

Ballistic electron emission microscopy (BEEM) has been performed on both Au/Fe81 C19/Si (001) and Au/Fe/Si (001) Schottky diodes at 80 K. The Schottky heights were measured to be 0.68±0.02 eV and 0.70±0.02 eV for the Fe81 C19/Si (001) and Fe/Si (001) interfaces, respectively. In addition, a second threshold voltage was observed for the Fe/Si (001) interface at 1.29±0.04 eV and attributed to an additional conduction band minimum at the interface that arises from the bonding of the Fe to the Si. The hot electron attenuation lengths at 1.25 eV were measured to be 3.5±1.0 nm and 3.0±0.9 nm for Fe81 C19 and Fe, respectively. The attenuation length of the Fe81 C19 showed a decrease with increasing energy consistent with the universal curve for electron-electron scattering. However, the attenuation length for the Fe showed this decrease only until the onset of the second threshold after which it increased. It is proposed that this increase is attributed to the parallel momentum distribution of the additional conduction band minimum at the Fe/Si (001) interface.