Nitrogen gas flow driven voltage production of self assembled monolayer coated doped p-type and n-type silicon wafers

Report here a gas flow driven voltage production over a modified surface of doped p-type and n-type Silicon (Si) wafer at a modest velocities of subsonic regime where Mach number <; 0.2. The principle behind the voltage generation is an interesting interplay of Bernoulli´s principle and Seebeck effect. The pressure difference along the gas flow over the inclined Si surface at an angle π/4 produces a temperature gradient and which in turn produce a potential difference across the Si wafer. The produced voltage differs proportionally with the flow velocity and the Seebeck coefficient of the Si wafer. We modified the surface of the Si wafer with coating of 1H, 1H, 2H, 2H-Perflurooctyl trichlorosilane (FOTS) (only half area of the active region are coated with FOTS). Due to the high thermal stability of FOTS, it improves the temperature differences in the Silicon wafer coated with FOTS. We measured flow induced Seebeck voltage of uncoated p-Si and n-Si wafer and surface modified p-type and n-type Silicon wafers. The morphology of the modified surface is characterized by SEM analysis and the signal voltage produced is measured by National instruments NI-PXI-8108 workstation. Our results highlights the modified silicon wafer has potential to use as a gas flow sensing element and energy conversion device based on the direct generation of electrical signal.