Highly Enhanced H 2 Sensing Performance of Few-Layer MoS 2 /SiO 2 /Si Heterojunctions by Surface Decoration of Pd Nanoparticles.

A novel few-layer MoS2 /SiO2 /Si heterojunction is fabricated via DC magnetron sputtering technique, and Pd nanoparticles are further synthesized on the device surface. The results demonstrate that the fabricated sensor exhibits highly enhanced responses to H2 at room temperature due to the decoration of Pd nanoparticles. For example, the Pd-decorated MoS2 /SiO2 /Si heterojunction shows an excellent response of 9.2 × 103 % to H2 , which is much higher than the values for the Pd/SiO2 /Si and MoS2 /SiO2 /Si heterojunctions. In addition, the H2 sensing properties of the fabricated heterojunction are dependent largely on the thickness of the Pd-nanoparticle layer and there is an optimized Pd thickness for the device to achieve the best sensing characteristics. Based on the microstructure characterization and electrical measurements, the sensing mechanisms of the Pd-decorated MoS2 /SiO2 /Si heterojunction are proposed. These results indicate that the Pd decoration of few-layer MoS2 /SiO2 /Si heterojunctions presents an effective strategy for the scalable fabrication of high-performance H2 sensors.