Enhancing gas sensing properties of graphene by using a nanoporous substrate

Abstract

Substrate engineering is shown to be a viable approach for improving the use of graphene thin films for gas sensor applications. The performance of two-terminal devices fabricated on smooth SiO 2 and nanoporous anodized aluminum oxide (AAO) substrates are compared. Raman studies indicated that both types of samples exhibit similarly low point-defect densities, but the mobility values of the SiO 2supported films were found to be three times larger than those on porous AAO substrates. However, the AAO-supported graphene devices exhibit a 3-fold enhanced sensitivity to both NO 2 and NH 3 gases when compared to the devices supported on SiO 2 . We attribute this sensitivity enhancement to the inhomogeneous electrostatic potential landscape that results from the porous nature of the AAO substrate, as well as extended defects made of wrinkles or folds originated from AAO. This substrate design strategy could be extended to other semiconductor-based sensor devices.

NEMS Resonators for Detection of Chemical Warfare Agents Based on Graphene Sheet

“…Analyzed mode shapes points out that if the mass of attached nanoparticle and the nonlocal parameter is low the resonant frequency is around 8 -30 GHz depending on the mode shape. As the mass of the attached nanoparticle and the nonlocal parameter gets larger the resonant frequency drops down to a MHz range which is closer to experimentally obtained results [19,50,51].…”

“…(ii) For small dimensions of SLGS or DLGS the natural or resonant frequencies in MHz range (obtained in experimental investigations [19,50,51]) could be obtained by the nonlocal theory in the absence of dissipation mechanisms, only if the nonlocal parameter is greater than 20 nm.…”

“…So far, the NEMS resonators based on graphene sheets were being used for investigating detection from theoretical and experimental point of view with simple chemical compounds such as H 2 , H 2 0, O 2 , CO 2 , CO, NO 2 , Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt [11]. Although the graphene as a building block of gas sensor has high sensitivity to gas molecules the proof-of-principle comparison studies [19] showed that graphene sensing capabilities could be enhanced using a nanoporous substrate.…”

“…Since the focus of this paper is not to determine the true value of the nonlocal parameter but to examine the possibility of using graphene in CWA molecule detection, the nonlocal parameter in further analyses will range from 1 to 4 nm. It should be emphasized that experimental investigations [19,50,51] showed that resonant frequencies of graphene sheets are lower (MHz range) when compared to results obtained using the nonlocal theory of elasticity (GHz range) [1,4,31,34]. This difference in frequency is due to the fact that the effect of all dissipative mechanisms on the experimental system is not known and because the exact value of the nonlocal parameter is still unknown, which represents the main disadvantage of the nonlocal theory for smaller values of the nonlocal parameter.…”

Enhancing the response of NH3 graphene-sensors by using devices with different graphene-substrate distances

“…Therefore, our findings confirm that the G/substrate distance plays an important role on NH3 graphene-sensor characteristics such as change transfer, resistance response and recovering. Additionally, it confirms that in order to develop new graphene sensors one must to consider the substrate engineering as a fundamental step during the devices fabrication[27][28][29][30].…”