Low-resistance titanium/n-type silicon (1 0 0) contacts by monolayer selenium passivation

Abstract

Low-resistance Ohmic contacts fabricated by selenium passivation between titanium and n-type silicon (1 0 0) substrates have been characterized by the four-point probe and circular transmission line method. Selenium passivation terminates dangling bonds on the Si(1 0 0) surface and reduces the Schottky barrier height between Ti and n-type Si(1 0 0) substrates. Sheet resistance of the Ti–Si contacts on Se-passivated 1019 cm−3 doped Si substrates shows a ∼30% reduction as compared with control samples. Accordingly, the extracted contact resistance is reduced by about an order of magnitude for samples with different Ti thicknesses and different annealing temperatures. A 29-times reduction in contact resistivity is achieved by Se passivation on highly-doped Si-on-insulator substrates with a 500 Å un-doped Si buffer layer.