Study of the effect of CNTs, and (CNTs-ZnO) on the porous silicon as sensor for acetone gas detection

Abstract

This work deals with a thin coating of nanoparticles zinc oxide (ZnO) doped with carbon nanotubes (MWCNTs) about (30−70) % respectively, that deposited on porous silicon (PSi) surface. the PS were prepared by photoelectrochemical etching (PECE) at different etching current densities: J= 12, 24, and 30 mA/cm2 for 10 min of etching time and 40% hydrofluoric acid concentration, while the zinc nanoparticles (ZnO) were prepared by the precipitation method. the suspension solution of ZnO-MWCNTs was prepared by mixing 30% of ZnO with 70% of MWCNTs by using a magnetic stirrer for 20 min then in ultrasonic in 30 min for prepare homogeneity solution. the drops-casting method was used for departed 5 drops of,MWCNTs and (30–70) % ZnO-MWCNTs on PS surface. The structural, morphological, and optical properties were conducted for all samples using X-ray diffraction (XRD) analysis, Raman Spectroscopy, Field emission scanning electron microscopy (FSEM), atomic force microscopy(AFM), Transition Electron Microscope (TEM), and photoluminescence (PL) tests. At room temperature, all PS, MWCNTs/PS, and MWCNTs -ZnO/PS samples were used as acetone gas sensors.the best sensitivity was at MWCNT after doping with ZnO on PS samples at etching current density 30 mA/cm2, about (2.940814) at a concentration of 500 ppm. In comparison to MWCNTs/PS around (2.567534) and only PS surface (2.413857) This is due to the fact that after being deposited with ZnONPs, MWCNT nanostructures have a high surface chemical activity and a big specific surface area. This makes MWCNTs act as highly sensitive to many gases such as ethanol, and acetone gases at room temperature (RT).