High-performance hydrogen sensing properties and sensing mechanism in Pd-coated p-type Si nanowire arrays

•The H2 sensing performance and sensing mechanism in Pd-coated n- and p-type Si NW arrays was demonstrated.•The resistance of the Pd-coated n-type Si NWs decreased from the base resistance, whereas that of the p-type Si NW arrays increased, upon exposure to H2.•The sensitivity (S=1700% at 1% H2) of Pd-coated p-type NW arrays was much greater than that of the n-type NW arrays (S=75%).•The dependency of the change in carrier density on H2 concentration was significantly greater in p-type Si NW arrays, while it was negligible in the n-type NW arrays.