field effect transistors and method for forming filed effect transistors . the field effect transistors including : a gate dielectric on a channel region in a semiconductor substrate ; a gate electrode on the gate dielectric ; respective source / drains in the substrate on opposite sides of the channel region ; sidewall spacers on opposite sides of the gate electrode proximate to the source / drains ; and wherein the sidewall spacers comprise a material having a dielectric constant lower than that of silicon dioxide and capable of absorbing laser radiation .