Integration of P-CuO Thin Sputtered Layers onto Microsensor Platforms for Gas Sensing

Abstract

P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH3), acetaldehyde (C2H4O), and nitrogen dioxide (NO2) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins. Because the microheaters were designed on a membrane, it was then possible to generate very rapid temperature variations (from room temperature to 550 °C in only 50 ms) and a rapid temperature cycling mode could be applied. This measurement mode allowed a significant improvement of the sensor response under 2 and 5 ppm of acetaldehyde.

Ga doped ZnO thin films deposited by RF sputtering for NO2 sensing

“…ZnO thin films are usually prepared using methods like sol-gel [16], spray pyrolysis [10], sputtering [3], chemical vapor deposition [17], and pulsed laser deposition [18]… The physical deposition, especially the RF sputtering [19] seems more convenient compared to solution processes in order to get high purity thin films. Moreover, by controlling the deposition parameters, the optimum microstructure with the adapted inter granular porosity can be obtained for better sensing properties.…”

Fabrication of Gas-Sensor Chips Based on Silicon–Carbon Films Obtained by Electrochemical Deposition

“…Thus, we can conclude that our sensors are not inferior in their characteristics to others reported in the literature. Also, sensors of both type-1 and -2 detect CO at a concentration of 16 ppm, while wellknown CuO-based sensors determine concentrations of at least 200 [36] and 2000 [45] ppm. Only one source [50] reported a CuO sensor for 10,000 ppm CH4 detection at 300 °C, while our sensors detect 297 ppm of methane at 200 °C.…”

“…Only one source [50] reported a CuO sensor for 10,000 ppm CH4 detection at 300 °C, while our sensors detect 297 ppm of methane at 200 °C. known CuO-based sensors determine concentrations of at least 200 [36] and 2000 [45] ppm. Only one source [50] reported a CuO sensor for 10,000 ppm CH4 detection at 300 °C, while our sensors detect 297 ppm of methane at 200 °C.…”

“…The operating temperatures of sensors in most cases reach 200-500 • C. Thus, we can conclude that our sensors are not inferior in their characteristics to others reported in the literature. Also, sensors of both type-1 and -2 detect CO at a concentration of 16 ppm, while well-known CuO-based sensors determine concentrations of at least 200 [36] and 2000 [45] ppm.…”

Evolution of Wireless Sensor Network for Air Quality Measurements

“…Therefore, such sensors include an integrated heating element. The pulsed-temperature operating mode [35] consists of using short heating or cooling pulses from a reference temperature (ambient, high, or intermediate temperature). This mode of operation promotes transient chemical reactions.…”