The impact of boron dopant segregation on the carrier density in silicon nanowires and ohmic contact formation is studied. Based on electrical measurements of individual nanowires and a secondary ion mass spectroscopy study, we show that an oxidation at high temperatures reduces the active carrier density of the silicon nanowires due to the onset of dopant segregation. On the other hand, improved ohmic contact resistivities as low as 6E-7 Ω⋅cm² is achieved by dopant surface segregation during the thermal formation of platinum silicided contacts. We show, that the contact resistivity decreases with increasing contact pad area for silicided, as well as non-silicide nanowires. Furthermore, it is also demonstrated that the achieved ohmic contacts can be used to realize junctionless nanowire transistors.