ZnTe-coated ZnO nanorods: Hydrogen sulfide nano-sensor purely controlled by pn junction

In this study, the double hydrothermal method is proposed as a facile approach to the synthesis of ZnTe/ZnO core–shell nanorods. The coating thickness of the p-type ZnTe is varied to adjust the junction depth in the n-type ZnO nanorods, and the conductance measurements reveal the change in the conduction path in the heterojunction structures. Structural and chemical investigations conducted using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy confirm the hetero-nanostructure formation of ZnTe/ZnO. The role of ZnTe in H2S-gas sensing by the ZnO nanorods is discussed. The enhanced sensing performance observed with a thin ZnTe coating confirms the importance of the base resistance of the nano-transducer in achieving high response characteristics. The composite structure also demonstrates a superior sensing performance of good repeatability, stability, linearity, and gas selectivity at temperatures greater than 200 °C. © 2020