The Review of Semiconductor Gas Sensor for Nox Detcting

Abstract

During the last century, many semiconductor gas sensors have been presented based on various materials and technologies to detect gas components. Many of them are made to support human's life in different ways. In the last years, the number of sensors which can detect various gas species has increased dramatically especially with respect to global issues of environment and earth atmosphere, the necessity of those gas sensors which can detect air pollutants such as NO x gases in environment is felt. They are essentially required in order to control the systems of combustion exhausted from industry, stationary facilities and automobiles. So it is necessary for the scientists to design and fabricate the gas sensors which are of low cost, selective, sensitive, and accurate especially in low level concentrations of target gases, easy to process and of high recovery and response time, good electrical properties, and above all tunable structure at the nano scale. In this sense, this paper has presented various classifications of gas sensors and various semiconductor oxides for NO x detecting and their technology to convey a comprehensive idea about the semiconductor metals as well as metal oxides for NO x detecting along with their characteristics, structures etc. in order to clarify the future road map towards on the semiconductor materials for NO x detecting. Keywords: sensor, NO x gases, semiconductor, metal oxides INTRODUCTIONIn the last few decades, many studies have been focused on the semiconducting metal oxides which are known as effective gas sensing materials especially for NO x detecting due to their electrical conductivities which are open to change greatly with the changes of atmosphere (K. J. Choi & Jang, 2010;Comini et al., 2009;Fine, Cavanagh, Afonja, & Binions, 2010;Franke, Koplin, & Simon, 2006; Kanan, El-Kadri, Abu-Yousef, & Kanan, 2009; G Korotcenkov & Cho, 2011;J.-H. Lee, 2009;Tricoli, Righettoni, & Teleki, 2010;Wetchakun et al., 2011). The sensing characteristics of such sensors can be optimized by controlling their morphology, surface to volume ratio, and electrical properties. The developments in nanotechnology, fabrication methods, and synthesis provide a suitable atmosphere to construct those sensors with their mentioned sensing characteristics easier.

ZnO@ZIF-8 Core-Shell Structure Gas Sensors with Excellent Selectivity to H2

“…Under thermal excitation conditions, the carrier of the sensor increases, leading to an increase in conductivity and a decrease in resistance. Under constant temperature conditions, the resistance of a gas sensor mainly depends on the amount of oxygen absorbed [44]. O 2 attached to the surface of the gas-sensitive material absorbs electrons in the conduction band of ZnO, resulting in a reduction in the number of carriers and an electron depletion layer.…”

A Gas Sensor Based on a Single SnO Micro-Disk

“…Considerable progress has been made over the past decades in minimizing such emissions by the introduction of various emission sensors (e.g., zirconia-based electrochemical oxygen sensors) [ 2 , 3 ], catalysts (e.g., three-way catalysts) [ 4 ] and traps (e.g., lean NO x traps) [ 5 ]. Recent reports have emphasized the continued challenges associated with the cost-effective detection and minimization of NO x emissions from diesel engines [ 6 ].…”

Recent Progress on Nanomaterials for NO2 Surface Acoustic Wave Sensors

“…LGS-langasite; LiTaO 3 -lithium tantalate; NA-data not available; RT-room temperature; SAWR: SAW resonator. Numbered notes: (1) The authors reported measurements over the limited 80-250 ppm NO 2 concentration range; (2) These limits are estimated, based on measurements over the limited 0.3-3 ppm NO 2 concentration range; (3) Both values were estimated based on the graphs shown in Figure 5 of [30]; (4) The authors used a dual SAWR (dual SAW resonator), measuring the oscillation frequency with a frequency meter.…”

“…In recent years, different types of NO 2 sensors have been developed based on sensing materials, fabrication technologies, input signals and conversion mechanism or sensor features (such as cost, stability or accuracy). Most studied NO 2 sensors are metal oxide semiconductor sensors [4][5][6][7], catalytic-type sensors [8], electrochemical sensors [9,10] and acoustic-based sensors [11][12][13].…”