Passivation of Si(100) Surface by S from a Solution and Its Effect on Schottky Barrier Height

摘要

A wet-chemical process has been developed to passivate the Si(100) surface with S in an aqueous solution. The solution contains an etchant for SiO_2, ammonium hydroxide [NH_4OH], and a passivant, ammonium sulfide [(NH_4)_2S]. The compatibility of the etchant with the passivant allows SiO_2, native or thermal, to be removed in-situ. A fresh and clean Si(100) surface is exposed right before the surface is passivated by S. To monitor the passivation quality, Schottky barrier heights of Al and Ni on S-passivated n-type and p-type Si(100) have been measured. Due to the passivation of dangling bonds by S, surface states are reduced to a great extent and Schottky barrier heights of Al and Ni on Si(100) show a greater sensitivity to their respective work functions. Our experimental results also reveal that surface states dominate over surface dipole in controlling the Schottky barrier height in these metal-Si systems.