Germanium-concentration dependence of arsenic diffusion in silicon germanium alloys

Abstract

The germanium-concentration dependence of arsenic diffusion in relaxed silicon germanium (Si1−xGex) alloys with Ge content ranging from 0 to 40% has been investigated. Arsenic was implanted into relaxed epitaxial layers at 15 keV to a dose of 3×1015 cm−2, and diffusion during furnace and rapid thermal annealing was studied. Under equilibrium extrinsic conditions, the arsenic diffusivity increases exponentially with increasing Ge content in Si1−xGex. Under transient diffusion conditions, the arsenic diffusivity in Si1−xGex is retarded compared to the diffusivity for longer times, while a slight transient enhancement of As diffusion is observed in Si. The degree of transient retardation depends on the germanium concentration in the alloy.