Au Doping ZnO Nanosheets Sensing Properties of Ethanol Gas Prepared on MEMS Device

Sensitivity of the Micro Electro Mechanical System (MEMS) device ZnO nanosheets sensor and the Au doped ZnO nanosheets sensor has been investigated. The ZnO samples have been prepared using Hydrothermal synthesis at 90 °C. The prepared ZnO nanostructure is tested for structural morphology and crystallinity properties. The elemental analysis of the ZnO sample and Au–ZnO samples are tested by using Energy Dispersive X-ray Spectroscopy (EDS) spectrum analysis. MEMS device microheater is designed and prepared for testing the sensitivity of Ethanol gas. Thermal properties of the MEMS microheater is studied for better gas testing at different temperatures. Both the ZnO nanosheets sensor and Au doped ZnO nanosheets sensor are tested using Ethanol gas, and the gas concentrations are taken to be 15, 30, 45, and 60 ppm at 300 °C. The gas sensing response of pure ZnO nanosheets tested for ethanol gas at 60 ppm showed 20%, while the Au–ZnO nanosheets showed 35%, which is increased by 15% at similar operating conditions

Optical properties and growth mechanism of rock-like structured black silicon

In this study, rock-like black silicon is prepared by using plasma enhanced hot-wire chemical vapor deposition (PE-HWCVD). The average grain sizes of polysilicon for 10-min, 20-min and 40-min growth time was about 12.4, 14.3 and 15.5 nm, respectively. As the growth time increased, the surface morphology had more rock like structures all over the surface which can be seen in the scanning electron microscope (SEM). Growth mechanism of developing crystalline silicon is studied along with the optical property. The results showed that the PE-HWCVD silicon have low reflectivity 6.4% better than wet etch textured silicon 12.5% in the range of 400–800 nm. The black silicon has low reflectance than the wet etch textured silicon which can be perfectly used as an anti-reflective coating substance

High selectivity Fe3O4 nanoparticle to volatile organic compound (VOC) for MEMS gas sensors

In the current study, XRD analysis shows the polycrystalline form an inverse spinel Fe _3 O _4 structure. Fe _3 O _4 film is prepared by dip coating method on MEMS gas sensors to test the sensitivity on volatile organic compound (VOC) gas. VOC is being tested at 92 mW (∼300 °C) power consumption with different VOC gas concentrations and also tested with different gases like NO _2 , SO _2 , NH _3 and CO gas. The results showed that the Fe _3 O _4 gas sensor has better selectivity and high response with VOC 1.2 ppm concentration. Structural morphology is seen and reaction mechanism when VOC gas reacts with Fe _3 O _4 material is also being discussed

AZO-Based ZnO Nanosheet MEMS Sensor with Different Al Concentrations for Enhanced H₂S Gas Sensing

The properties of H2S gas sensing were investigated using a ZnO nanostructure prepared with AZO (zinc oxide with aluminium) and Al surfaces which were developed on a MEMS (Micro Electromechanical System) device. Hydrothermal synthesis was implemented for the deposition of the ZnO nanostructure. To find the optimal conditions for H2S gas sensing, different ZnO growth times and different temperatures were considered and tested, and the results were analysed. At 250 °C and 90 min growth time, a ZnO sensor prepared with AZO and 40 nm Al recorded an 8.5% H2S gas-sensing response at a 200 ppb gas concentration and a 14% sensing response at a gas concentration of 1000 ppb. The dominant sensing response provided the optimal conditions for the ZnO sensor, which were 250 °C temperature and 90 min growth time. Gas sensor selectivity was tested with five different gases (CO, SO2, NO2, NH3 and H2S) and the sensor showed great selectivity towards H2S gas