Reduction of Schottky barrier height and contact resistivity in metal contacts to n-type silicon by insertion of interfacial arsenic monolayers

Abstract

Interfacial arsenic monolayers are used to reduce the Schottky barrier at metal contacts to n-type silicon and consequently reduce the resistance of such contacts. Building on earlier work on group V elemental monolayers and III-V atomic bilayers on (111) silicon, we confirm for the first time that interfacial engineering may achieve very significant reduction of contact resistivity, by a factor of about 100 for aluminum contacts to n-type silicon doped 1 × 1019 cm−3. The effect of an arsenic monolayer is explained theoretically based on the formation of an additional electronic dipole between the metal and the silicon which acts to counter the pinned Schottky barrier between the two. Arsenic monolayers are formed by MBE, RPCVD and MOVPE and characterized through a combination of RBS and SIMS analysis.