Effect of varying the nanostructured porous-Si process parameters on the performance of Pd-doped hydrogen sensor

The process parameters of a nanoporous silicon-based Pd-doped H2 system were varied to investigate the sensor response. In particular, the influence of anodization current density, etching time and active layer (Pd) thickness were correlated to the sensor's response time and stability. The structure and morphology of the pores along with Pd distribution in the porous matrix has been found to govern the sensor response. Additionally, formation of Pd2Si in samples etched for 45 min and nucleation of silica nanowires for 12 nm thick Pd samples were experimentally observed. The change in electrical resistance was monitored while testing the device in the range of 0–1.5% H2. The optimal process parameters for stable and rapid sensing of H2 were found in samples etched for 30 min subjected to an anodic current density of 10.2 mA/cm2.