Analysis of synthesized doped vertical silicon nanowire arrays for effective sensing of nitrogen dioxide: As gas sensors

Abstract

In the present study, the controllable fabrication of silicon nanowires (Si NWs) with vertical alignment was accomplished using metal assisted chemical etching (MACE). The different characteristics, such as structural, morphological, chemical, optical, and dielectric properties were analyzed using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), and LCR [inductance (L), capacitance (C), and resistance (R)] meter (volume of the gas-sensing chamber is 650 mm3). It was revealed from the morphological study i.e., from the FESEM that p-type Si NWs are smaller in size than n-type Si NWs which is attributable to the energy band gap. The optical band gap (Eg) is observed to increase from 1.64 to 1.89 eV with the decreasing of the crystallite size and the optical reflection spectra of the Si NWs show a shift toward a lower wavelength (blue shift). Moreover, Raman spectra verified the red-shifted, asymmetrically broadened Raman line-shapes, which provides information about the size confinement effect in Si NWs. The MACE approach is excellent for synthesizing nanowire structures for use in gas-sensing applications due to its flexibility. The sensitivity of synthesized Si NWs was tested for NO2 gas. The sensor method is unique based on the testing of the device in the presence of a test gas because the use of the gas-sensing setup has the potential to measure the change in resistance by varying frequency, temperature, and time.

The dopant (n- and p-type)-, band gap-, size- and stress-dependent field electron emission of silicon nanowires

“…Among them, catalyst-induced etching (CIE) is a wet-chemical method, which is a particularly fascinating and promising approach, because of its good costefficiency and the ease of massive production. [13][14][15] The chemical mechanism involved in fabrication of Si NWs by the CIE approach is given in the ESI. † To date, various groups have tried to utilize Si based structures for various applications.…”

NO2 Gas Sensor Based on Pristine Black Silicon Formed by Reactive Ion Etching

“…As the gas-sensing principle is associated with a surface phenomenon rather than with a bulk phenomenon, the trend is to develop gas sensors using materials with high surface area morphologies such as micro-and nanoscale porous Si (PSi). [3][4][5][6][7][8][9][10][11][12] The conventional methods to fabricate microscale PSi (microPSi) are electrochemical or stain etching in solutions based on hydrofluoric acid (HF). Nanoscale PSi (nanoPSi) is fabricated by the metal-assisted chemical etching (MACE) method using nonuniform etching of Si substrates in aqueous acid solutions, which is catalyzed by electroless deposition of metal nanoparticles (NPs) on the substrate surfaces.…”