Fermi-level pinning of aluminium on n-type germanium (n-Ge) was reduced by insertion of a thin interfacial dielectric by atomic layer deposition. The barrier height for aluminium contacts on n-Ge was reduced from 0.7 eV to a value of 0.28 eV for a thin Al2O3 interfacial layer (∼2.8 nm). For diodes with an Al2O3 interfacial layer, the contact resistance started to increase for layer thicknesses above 2.8 nm. For diodes with a HfO2 interfacial layer, the barrier height was also reduced but the contact resistance increased dramatically for layer thicknesses above 1.5 nm.
Gajula, D. R., Baine, P., Modreanu, M., Hurley, P. K., Armstrong, B. M., & McNeill, D. W. (2014). Fermi level de-pinning of aluminium contacts to n-type germanium using thin atomic layer deposited layers. Applied Physics Letters, 104(1), . https://doi.org/10.1063/1.4858961