We report on the H2 sensing performance and sensing mechanism in Pd-coated n- and p-type Si nanowire (NW) arrays, which were fabricated by an aqueous electroless etching method and sputtering. We found that 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%). Furthermore, we found that 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. A Schottky barrier was formed between the Pd and n-Si (ϕM > ϕSC) before exposure to H2, which changed to an Ohmic contact (ϕM < ϕSC) after H2 exposure. In contrast, an Ohmic contact was formed between the Pd and p-Si (ϕM > ϕSC) before exposure to H2, which, after exposure, changed to a Schottky barrier (ϕM < ϕSC). Therefore, the p-type Si NW arrays were much more sensitive to H2 than the n-type Si NW arrays.
Bibliographical noteFunding Information:
This work was supported by the Korean government (MSIP) (2014R1A2A1A10053869), and the Priority Research Centers Program (2009-0093823) through the National Research Foundation of Korea (NRF).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry