Free carrier lifetime measurements in SiGe/Si planar waveguides

In this paper we report minority carriers lifetime measurements in a set of SiGe/Si planar waveguides fabricated by low-energy plasma enhanced chemical vapour deposition (LEPECVD), a originally developed for microelectronic applications that can be conveniently exploited for photonic applications. Several waveguides have been fabricated with a Ge concentration ranging from 2% to 6% and different thicknesses ranging from 200 nm to 2 mum. Lifetimes were measured by generating electron-hole pairs with a 100 fs laser pulse emitted at 810 nm, and monitoring the free-carrier absorption transient with a c.w. probe beam at 1.55 mum.