The Effect of Current Density on the Properties of Porous Silicon Gas Sensor for Ethanol and Methanol Vapour Detection

Abstract

In this paper, Gas sensors for ethanol and methanol were created utilizing porous silicon (PSi).n-type silicon was employed for all PSi samples, photo-electrochemical etching technique (PECE) was used to prepare porous surface. The intensity of the three etchings current densities was 12, 24 and 30 mA / cm2, with 40% hydrofluoric acid concentration (HF) and a time of etching 10 minutes. Porous silicon (100) has been strictly studied by the structure and formation of surface bonding of the PSi layer; the structural properties, morphological characteristics, pore diameter, and roughness were described using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). All PSi samples were applied as a sensor for ethanol and methanol at room temperature. The results showed that the best sensitivity of PSi was to ethanol gas compared to methane under the same used conditions at etching current density 30mA/cm2, reaching about 1.809 at a concentration of 500 ppm. From these results, the PSi layers act as high-quality, low-cost gas sensors. It can be used as a replacement for expensive material that is used as gas sensors, which operate at low temperatures, including room temperature. The interest in this material is due to study the effect of extremely high surface to volume ratio (increasing surface area), and easy manufactured and compatibility with modern silicon microelectronics manufacturing technologies.

Keywords

• porous silicon (ps)
• ethanol gas sensor
• methanol gas sensor
• photo-electrochemical etching