Abstract
In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. It is based on the Kelvin probe approach. Porous ZnO nanostructured thin films deposited by the direct current (DC) reactive magnetron sputtering method are used as the active gas sensing electrode material. Crucially, the obtained gas sensing material exhibited a nanocoral surface morphology and surface Zn to O non-stoichiometry with respect to its bulk mass. Among other responses, the demonstrated SPV gas sensor device exhibits a high response to an NO2 concentration as low as 1 ppm, with a signal to noise ratio of about 50 and a fast response time of several seconds under room temperature conditions.
Highlights
Despite more than 50 years of development, the most common resistive type gas sensors systems based on metal oxide (MOX) materials still exhibit some critical and fundamental limitations [1,2,3,4], which can be divided into two groups: the first one concerns the analytically useful characteristics which are limited to good sensitivity combined with a rather poor selectivity, as well as poor dynamic parameters such as a long response time combined with a rather very long recovery time
In this paper we describe the proof-of-principle of the above mentioned surface photovoltage (SPV) gas sensor system based on the Kelvin probe approach utilizing porous zinc oxide (ZnO) nanostructured thin films as the active electrode
As was mentioned above in our SPV gas sensor system the porous ZnO nanostructured thin films deposited onto Si (100) substrate were used as the gas sensing material for which the bulk films deposited onto Si (100) substrate were used as the gas sensing material for which the bulk chemistry and morphology have been characterized by chosen experimental techniques [29] as shortly chemistry and morphology have been characterized by chosen experimental techniques [29] as summarized below
Summary
Despite more than 50 years of development, the most common resistive type gas sensors systems based on metal oxide (MOX) materials still exhibit some critical and fundamental limitations [1,2,3,4], which can be divided into two groups: the first one concerns the analytically useful characteristics which are limited to good sensitivity (usually at the level of single ppm, strongly depending on the gas) combined with a rather poor selectivity (strongly dependent on humidity, that can be improved by noble catalytic metals), as well as poor dynamic parameters such as a long response time (tens of seconds) combined with a rather very long recovery time (single minutes). Lately it was observed that low sensing effect of resistive type MOX gas sensors at room temperature can be improved by additional UV radiation, as nicely reviewed, mainly for various forms of ZnO gas sensors, among others, by Zhu and Zeng [8] and by Leonardi [9].
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