Double-Layered NiO/SnO2 Sensor for Improved SO2 Gas Sensing with MEMS Microheater Device

Micro Electro mechanical systems (MEMS) sensor is fabricated for testing low concentration gas sensing of sulphur dioxide (SO2) with sensing layers of single layer tin oxide (SnO2) and double layered heterojunction structure of nickel oxide and tin oxide (NiO/SnO2). NiO and SnO2 structures are deposited with RF sputtering and the elemental composition were identified with structural properties such as X-ray diffraction (XRD), Scanning electron microscope (SEM) and Energy Dispersive X-ray Analysis (EDX) analysis. Sensing results proved that NiO/SnO2 double layered sensor had better sensing characteristics than single layered SnO2 sensor due to the formation of p-n junctions. At 400 ppb of SO2 gas concentration, NiO/SnO2 sensor has maximum sensing response of 20% is recorded and at 2000 ppb, 30% sensing response is recoded. The optimal temperature of the sensor is 250 degrees C (similar to 63 mW). Selectivity of the sensor is tested with 5 different gases such as VOC, pyruvate, CO, NH3, SO2 and the sensor has high and better response with SO2 gas.

Automated summary

In this study, a Micro Electro Mechanical Systems (MEMS) sensor was fabricated for testing low concentration gas sensing of sulphur dioxide (SO2). The performance of a single layered tin oxide (SnO2) sensing layer and a double layered heterojunction structure of nickel oxide and tin oxide (NiO/SnO2) were compared, and it was found that the NiO/SnO2 double layered sensor had better sensing characteristics due to the formation of p-n junctions. The maximum sensing response of the NiO/SnO2 sensor was recorded as 20% at 400 ppb SO2 gas concentration, and 30% at 2000 ppb.