SnO₂ Nanoslab as NO₂ Sensor: Identification of the NO₂ Sensing Mechanism on a SnO₂ Surface

Abstract

Among the various metal oxides, SnO2 has been most widely exploited as a semiconductor gas sensor for its excellent functionalities. Models illustrating the sensing mechanism of SnO2 have been proposed and tested to explain experimentally derived "power laws". The models, however, are often based on somewhat simplistic assumptions; for instance, the net charge transfer from an adsorbate to a sensor surface site is assumed to occur only by integer values independent of the crystallographic planes. In this work, we use layer-shaped SnO2 crystallites with one nanodimension (1ND-crystallites) as NO2 gas sensing elements under flat band conditions, and derive appropriate "power laws" by combining the dynamics of gas molecules on the sensor surface with a depletion theory of semiconductor. Our experimentally measured sensor response as a function of NO2 concentration when compared with the theoretically derived power law indicates that sensing occurs primarily through the chemisorption of single NO2 molecules at oxygen vacancy sites on the sensor surface.

Dielectrophoretic assembly of Pt nanoparticle-reduced graphene oxide nanohybrid for highly-sensitive multiple gas sensor

“…Tin oxide and zinc oxide are two typical metal-oxide materials, which are used for gas sensing applications. Metal oxide-based gas sensors must be operated at high temperatures (200-400 • C) and this leads to high power consumption; this consumption is an impediment to downsizing of the hand-held type monitoring system or sensing module of ubiquitous sensor networks (USN) [1][2][3][4].…”

Application of AlGaN/GaN Heterostructures for Ultra-Low Power Nitrogen Dioxide Sensing

“…[5][6][7] Thick film metal oxide (MOX) sensors have demonstrated, strong, reversible, and inexpensive response toward oxidizing and reducing gases, but also require significant heating. 9,10 By reducing the thickness of the film on the order of a Debye length, a significant change in conductivity can be obtained. 11 ZnO on AlGaN/GaN has demonstrated response to high ppm concentrations of NO 2 .…”

“…SnO 2 is a well-known MOX for gas sensing with a high number of oxygen vacancies allowing for charge transfer between the surface and gas. 10 Ultra-thin films are required for this application to obtain films near the Debye length and allow for effective charge mirroring to occur from the surface to the 2DEG. For this reason, ALD was chosen for precise film thickness control.…”

Role of the heterojunctions in In2O3-composite SnO2nanorod sensors and their remarkable gas-sensing performance for NOxat room temperature

“…It is clear to see that the 3ICTO sensor 35 exhibits higher gas response to NO x than that of other gases, which is mainly because of the enhanced reaction between NO x and the absorbed oxygen (O 2 -) at RT. [59][60] Moreover, the insert in Figure 6E exhibits a linear calibration curve in the range of 0.1-100 ppm. The degree of linear correlation was evaluated by R 2 40 (R 2 =0.9939).…”