Fabrication techniques for NMOS and PMOS nanowires leveraging an isolated process flow for NMOS and PMOS nanowires facilitates independent (decoupled) tuning/variation of the respective geometries (i.e., sizing) and chemical composition of NMOS and PMOS nanowires existing in the same process. These independently tunable degrees of freedom are achieved due to fabrication techniques disclosed herein, which enable the ability to individually adjust the width of NMOS and PMOS nanowires as well as the general composition of the material forming these nanowires independently of one another. In the context of nanowire based semiconductors, in which NMOS and PMOS nanowires are incorporated as channel, drain and source regions respectively for NMOS and PMOS nanowire transistors, independent tuning of the NMOS and PMOS nanowires facilitates independent tuning of short-channel effects, gate drive, the width of the transistor dead space capacitance, strain and other performance related characteristics of associated NMOS and PMOS nanowire transistors.