Preparation, morphology and N ₂ -O ₂ analysis of palladium nanostructures-decorated porous silicon

Abstract Palladium nanoparticles and thin films show promising applications in the detection of hydrogen and organic molecules. Among the numerous preparation methods, the chemical redox method has the advantages of simplicity and low cost. In this work, palladium nanoparticles and thin films were prepared on three types of porous silicon with nanostructures, nano-straight pore composites, and regular arrays via redox electroless plating. The morphologies of the palladium particles and thin films were characterized by scanning electron microscopy. And Senor properties were performed in analyzing N 2 -O 2 mixed gases. The results show that palladium particles of tens of nanometers can be formed in the pores of all three types of porous silicon and maximum probability of diameter is sized around 190 nm. Due to the slow diffusion of the electrolyte during the immersion process, the number of palladium particles in the pores is relatively small. Nevertheless, a continuous palladium film with a thickness of 100–200 nm was formed on the surface of nano-porous silicon. This phenomenon is related to the continuous reduction of palladium chloride by Si-H x dangling bonds. Finally, the senor properties show the current response and the response delay in measuring are approximately linear as a function of the N 2 concentration.