Influence of ion-induced interfacial chemical reactivity on contact resistance

Contact resistance measurements of chromium contacts deposited by partially ionized beam deposition on transparent conducting indium tin oxide (ITO) were performed. These provide a direct experimental evidence of the influence of interfacial chemical interaction on the contact resistance. The interfacial reactivity is controlled by modifying the energy and flux of ionized chromium atoms deposited on ITO employing a specially designed partially ionized deposition system with very high ionization efficiency. The true contact resistivityρ _c is obtained by iteratively correcting the experimentally measured values for the finite sheet resistance of the ITO layer.ρ _c decreases linearly with the energy of the ionized chromium. Auger sputter profiling shows no structural modifications at the interface due to a change in the energy of the chromium atoms, confirming that the observed change in the contact resistivity is directly related to interfacial chemical bonding of the atoms with the oxygen atoms in the ITO leading to a local increase of carrier concentration and lower interfacial resistance.