Low-resistance Ti/n-type Si(100) Contacts by Monolayer Se Passivation

Abstract

Low-resistance contacts fabricated by selenium passivation between Ti and n-type Si(100) substrates have been characterized by low-temperature I-V, four-point probe and circular transmission line methods. The Ti-Si contacts on Se-passivated samples demonstrate a significant reduction in Schottky barrier height over control samples in low-temperature I-V. Sheet resistance of the contacts on Se-passivated 10 19 cm -3 doped n-type Si (100) substrates shows a 30% reduction as compared with control samples. Accordingly, the extracted contact resistance decreases by about one order of magnitude for samples with different Ti thicknesses and different annealing temperatures. A 125%-2900% reduction in contact resistivity is achieved by Se passivation on highly-doped n-type SOI substrates with 500 Å un-doped Si buffer layer. The reduction in contact resistance is attributed to the minimization of interface states between Ti and Si(100) surface.