Negative differential conductivity of lanthanum-oxide-based structures

Transparent surface-hydrogenated lanthanum-oxide films (La$_{2}$O$_{3}$) 40, 140, and 545 nm in thickness are fabricated using electron-beam evaporation. The electrical and optical characteristics of Al/OH–La$_2$O$_3$/$p$-Si structures are investigated. Aluminum and silicon substrates of $p$-type conductivity are used as the upper and lower electrodes of the structure, respectively. The region of negative differential conductivity is found in the voltage dependences of conductivity under forward bias; the possible mechanism of the negative differential conductivity is explained by proton transfer along chains of water molecules bound by hydrogen bonds on the surface of the OH–La$_{2}$O$_{3}$ film.