Rice-like tellurium thin films deposited by a galvanic displacement reaction and ultra-high sensing response to hydrogen sulfide (H2S) gas at room temperature

•Room-temperature operation of a robust and ultra-sensitive H2S gas sensor over rice-like tellurium (Te).•Facile direct deposition of Te on a silicon wafer by a galvanic displacement reaction without complicated procedures.•Lowest detection limit of 15 ppb H2S gas with a relatively high sensitivity of 21.5%.•Potential applications in silicon-based MEMS for micro-scale gas sensor devices. In this study, we present the synthesis of rice-like tellurium (Te) thin films using a galvanic displacement reaction (GDR, a substrate–sacrificial, electro-less deposition technique) on a silicon wafer and their response to hydrogen sulfide (H2S) gas at room temperature. The thin films were composed of rice-like Te nano grains, whose thickness and crystallinity were controlled by adjusting the reaction time of the GDR. As the reaction time increased, the as-fabricated rice-like Te-based gas sensors showed full response and recovery. The sensors with an optimized GDR showed ultra-high sensing response to H2S (∼1000% at 100 ppm of H2S) under ambient sensing conditions, with excellent response toward H2S gas (ranging from 15 ppb to 90 ppm). Additionally, the optimized sensor shows relatively high response toward H2S gas as compared to other gases such as NO2, NH3, and CO. Together, these results indicate that the rice-like tellurium (Te) thin films have great potential for applications in high-performance H2S gas sensors that are capable of operating at room temperature.