Silicon Nanowire based field effect transistors (FETs) have shown to be capable of label-free and real-time detection of biomolecules in fluidic media. Antagonist binding events lead to a gating effect and therefore a change in source-drain current. Next generations of biosensor FETs have to become more sensitive and strategies have to be developed to handle sample related screening and parasitic pH effects. Our research is focused on utilization of bottom-up synthesised Schottky barrier FETs (SB-FETs) for this new kind of sensors. Silicon nanowires grown with catalytic chemical vapor deposition (CVD) are contacted to Nickel pads which form source and drain. Annealing leads to axial nickel-silicidation resulting in an atomic sharp metal-semiconductor interface and therefore a defined Schottky barrier. So build SB-FETs show inverse subthreshold slopes as low as 110 mV/dec and a high on/off current ratio. This indicates the possibility of manipulating the barrier height by applied electrical fields in a very efficient way. Using this SB-FET as a detector for biological species promises therefore a very high sensitivity. Current investigations on the nature of the sensing effect on protein adsorption are running. The effect on the sensing regions (Schottky junctions vs. channel) will be assessed.