Effect of electrode configuration on capacitive humidity sensitivity of silicon nanoporous pillar array

Through evaporating two-side comb electrodes and coplanar interdigital electrodes, two humidity sensors were fabricated based on silicon nanoporous pillar array (Si-NPA) and the corresponding device sensitivities were studied. The experimental results showed that the sensor with coplanar interdigital electrodes could exhibit higher sensitivity than that with two-side comb electrodes. Based on the structural and physical properties of Si-NPA, the equivalent circuits for the two sensors were put forward and the theoretical evaluation on the effect of electrode configurations on device sensitivity was carried out through simulation and approximate calculation. The experimental results were well explained by the theoretical calculations qualitatively.