Single and networked CuO nanowires for highly sensitive p-type semiconductor gas sensor applications

Abstract

Development of high‐performance p‐type semiconductor based gas sensors exhibiting fast‐response/recovery times with ultra‐high response are of major importance for gas sensing applications. Recent reports demonstrated the excellent properties of p‐type semiconducting oxide for various practical applications, especially for selective oxidation of volatile organic compounds (VOCs). In this work, sensors based on CuO nanowire (NW) networks have been successfully fabricated via a simple thermal oxidation process on pre‐patterned Au/Cr pads. Our investigation demonstrates high impact of the process temperature on aspect ratio and density of copper oxide NWs. An optimal temperature for growth of thin and densely packed NWs was found to be at 425 °C. The fabricated sensors demonstrated ultra‐high gas response by a factor of 313 to ethanol vapour (100 ppm) at an operating temperature of 250 °C. High stability and repeatability of these sensors indicate the efficiency of p‐type oxide based gas sensors for selective detection of VOCs. A high‐performance nanodevice was fabricated in a FIB‐SEM system using a single CuO NW, demonstrating an ethanol response of 202 and rapid response and recovery of ∼198 ms at room temperature. The involved gas sensing mechanism of CuO NW networks has been described. We consider that the presented results will be of a great interest for the development of higher‐performance p‐type semiconductor based sensors and bottom‐up nanotechnologies. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Hybridization of Zinc Oxide Tetrapods for Selective Gas Sensing Applications

“…4 Due to specific surface conduction mechanism of p-type semiconducting oxides, the gas sensing mechanism is dominated by copper oxide. [12][13][14] It can be observed from Figure 5c, that the highest gas response of ZnO-T-ZnAl2O4…”

“…[3][4][12][13][14] As above mentioned, before the integration of ZnO-T-MexOy and ZnO-TZnxMe1-xOy (Me = Fe, Cu, Al) hybrid networks into the sensor structure, the as-produced samples were subjected to thermal annealing in an electrical furnace at 1150 ºC for 5 h in air.…”

“…The gas sensing measurement procedures were realized following the same procedure described in previous reported works. 3,[12][13][14] Concentration of all tested gases (H2, ethanol vapour (EtOH), CO and CH4) was 100 ppm, as in previous works. 3,15 The relative humidity (RH) value during the measurements was set at normal ambient conditions of 30% RH, and was continuously measured by a standard hygrometer inside the test chamber.…”

Multifurcation Assembly of Charged Aerosols and Its Application to 3D Structured Gas Sensors

“…CuO nanowire 400 500 0.6 (ΔR/R air ) [32] CuO nanofiber 200 500 2.8 (ΔR/R air ) [33] CuO nanowire 300 100 0.2 (ΔR/R air ) [34] CuO nanowire 325 30 0.29 (ΔR/R air ) [35] CuO nanowire 250 100 17.6 (ΔR/R air ) [36] CuO nanoparticle 300 100 1.75 (ΔR/R air ) present work…”

“…[38] Furthermore, networked CuO nanowires were demonstrated to enhance the performance of the gas sensor greatly. [36] Copper oxide reacts with reduction gas and also oxidation gas at a suitable temperature. At 100-500 °C, oxygen molecules adsorbed onto the surface of copper oxide are ready to respond to CO gas, which changes the conductivity of the sensing materials as a result of the reaction equation [39] (Equation (2) …”