Preparation high quality ethanol gas sensor by modifying porous silicon (PS) surface with carbon nanotube (CNTs)

Abstract

In the study, the high-quality gas sensor for ethanol was prepared by modified porous silicon (PS) with a thin layer of carbon nanotube. The PSi samples have been prepared by using the photoelectrochemical etching (PECE) process at various current densities J = 12, 24, and 30 mA/cm2 with 10 min etching time and Hydrofluoric acid concentration (HFC) of 40%. All samples (PSi and MWCNTs/PSi) were analyzed using X-ray diffraction (XRD), field emission Scanning electron microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Atomic Force Microscopic (AFM), to determine the structural, morphological, and surface bond configuration. As a result, the Photoluminescence (PL) test was performed on all samples using the PL system in order to calculate the energy band gap for all samples. Then the PSi and MWCNTs/PSi samples were applied as ethanol gas sensor at room temperature (RT). The results showed that the best sensitivity of ethanol gas was about (2.1912349) at a concentration of 500 parts per million (ppm) for MWCNTs/PSi sample compared to PSi surface, it was about (1.709) under the same used conditions at etching current density 30 mA/cm2. The MWCNTs/PSi layers serve as low-cost and high-quality ethanol gas sensors. The carbon nanotube used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The materials have an exceptionally high surface-to-volume ratio (increasing surface area), ease of fabrication, and compatibility with silicon microelectronics manufacturing processes.