Hydrogen Induced Dipole Layer in Pd-SiO2 Based Gas Sensors

A palladium (Pd) functionalized electrostatically formed nanowire (EFN) sensor, a silicon-on-insulator (SOI) based multi-gate transistor, has proven to be an ultra-sensitive platform for hydrogen (H
2
) sensing. This EFN includes a Pd– SiO
2
–Silicon, a metal-oxide-semiconductor (MOS) structure which is studied here in detail. We compare the EFN threshold voltage shift (∆V
TH
) due to H
2
adsorption, to the calculated ∆V
TH
due to dipoles placed at the Pd/SiO
2
interface of the EFN device. We show that the potential drop at the Pd/SiO
2
interface is responsible for the ultra-sensitive hydrogen sensing of the EFN.