Construction of MoS₂/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor

Few-layer MoS₂ thin films were synthesized by a two-step thermal decomposition process. In addition, MoS₂/Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS₂/SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS₂-based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ∼50% RH), with good repeatability and selectivity of the MoS₂/SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS₂/SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors. (paper)