Gallium Oxide as Oxygen Gas Sensors at a High Temperature (original) (raw)
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Sensors and Actuators B-chemical, 2003
The oxygen gas sensing performance of Ga2O3 semiconducting thin films doped with Ce, Sb, W and Zn have been investigated. These thin films have been prepared by the sol–gel process and were deposited on sapphire transducers with inter-digital electrodes and a platinum heater integrated. The sensors were exposed to various concentrations of oxygen gas in an ambient of nitrogen and the gas sensing performance has been examined. The responses of sensors doped with Ce, Sb, W and Zn were stable and reproducible at their respective operating temperatures. It was observed that Ga2O3 films doped with Ce, Zn and W are promising for oxygen gas sensing applications.
Oxygen Sensitivity in Gallium Oxide Thin Films and Single Crystals at High Temperatures
Japanese Journal of Applied Physics, 2006
In this paper, the oxygen sensitivity of gallium oxide thin films and single crystals at high temperatures is presented. To investigate the oxygen sensing mechanism at high temperature, we used sputtered-Ga 2 O 3 thin films and-Ga 2 O 3 single crystals with different electrode geometries. For-Ga 2 O 3 single crystals: a response time of about 10 s was achieved, while for-Ga 2 O 3 thin-film this was about 11 s. For single crystal samples the response time does not depend on the type of electrode. This can be explained by the combination of a greater influence of surface effects and smaller influence of bulk effects.
Investigation of sol–gel prepared Ga–Zn oxide thin films for oxygen gas sensing
Sensors and Actuators A: Physical, 2003
Gallium oxide-zinc oxide (Ga 2 O 3 -ZnO) thin films have been prepared by the sol-gel process and their oxygen gas sensing performance has been investigated. These semiconducting films were deposited on alumina substrates with interdigital electrodes and single crystal silicon substrates for the electrical and microstructural characterization. X-ray photoelectron spectroscopy (XPS) showed that the actual concentrations of Ga and Zn thin films differ from the nominal values in the prepared solutions. Additionally, the concentration of ZnO decreases when the annealing temperature increases. Scanning electron microscopy (SEM) revealed that films with Ga/Zn atomic ratio 90:10 possess cracks and are inhomogeneous when compared to those with that of 50:50. The sensors with Zn 50 at.% had a much larger response at lower operating temperature (<430 • C) compared to the Ga-dominated sensors, which operate above 450 • C. Furthermore, these sensors showed greatest performance at temperatures in the range of 380-420 • C. It was found that by increasing the amount of ZnO in the thin film sensors, the operating temperature decreased as well as the base resistance.
Ga2O3(Sn) Oxides for High-Temperature Gas Sensors
Nanomaterials
Gallium(III) oxide is a promising functional wide-gap semiconductor for high temperature gas sensors of the resistive type. Doping of Ga2O3 with tin improves material conductivity and leads to the complicated influence on phase content, microstructure, adsorption sites, donor centers and, as a result, gas sensor properties. In this work, Ga2O3 and Ga2O3(Sn) samples with tin content of 0–13 at.% prepared by aqueous co-precipitation method were investigated by X-ray diffraction, nitrogen adsorption isotherms, X-ray photoelectron spectroscopy, infrared spectroscopy and probe molecule techniques. The introduction of tin leads to a decrease in the average crystallite size, increase in the temperature of β-Ga2O3 formation. The sensor responses of all Ga2O3(Sn) samples to CO and NH3 have non-monotonous character depending on Sn content due to the following factors: the formation of donor centers and the change of free electron concentration, increase in reactive chemisorbed oxygen ions con...
Journal of Materiomics, 2019
The reliable, selective, and fast detection of the inorganic and organic gases in indoor and outdoor air and industrial processes is a huge challenge for environmental sustainability, healthier life, and disease control and diagnosis. Metal oxides have been frequently explored as highly sensitive receptor elements in the electronic gas sensors since the 1960s. Gallium oxide (Ga 2 O 3), often recognized as one of the widest-bandgap semiconductors, has shown tremendous potential as the inorganic gas receptor because of its extraordinary chemical and thermal stability, and excellent electronic properties. This article presents a comprehensive reference on the electrical properties, historical developments, detection mechanisms, and gas sensing performance of Ga 2 O 3 nanowires and composite nanostructures. In particular, the relationships between composition, nanostructure, and gas sensing properties of galliumcontaining oxidic nanomaterials such as b-Ga 2 O 3 nanowires, surface-modified Ga 2 O 3 , metal-doped Ga 2 O 3 or Ga-doped metal oxides, and Ga 2 O 3 /metal oxide composite heterostructures are studied. The applications of Ga 2 O 3 gas sensors are discussed with an emphasis on their practical limitations such as high-temperature operation, power consumption, and miniaturization issues. Finally, future research directions and potential developments are suggested.
SnO2:Ga thin films as oxygen gas sensor
Materials Science and Engineering B, 2004
Ga-doped SnO 2 thin films deposited by spray pyrolysis were investigated as oxygen gas sensors. Gallium was added to the films to enhance the catalytic activity of the surface's film to oxygen. Film resistance was studied in an environment of dry air loaded with oxygen in excess at partial pressures in the range from 0 to 8.78 × 10 3 Pa. The best sensitivity lies close to partial pressures of 133.3 Pa. Film sensitivity reach a maximum at 350 • C. For this temperature and a doping concentration of 3 at.% of Ga in the starting solution, a sensitivity up to 2.1 was obtained.
Chemistry of Materials, 2004
The reaction of gallium trichloride and methanol under atmospheric pressure chemical vapor deposition conditions leads to the production of gallium oxide thin films on a variety of substrates. Scanning electron microscopy (SEM) indicated that an island growth mechanism predominated. X-ray photoelectron spectroscopy (XPS) revealed binding energy shifts of 530.6 eV for O 1s and 20.3 eV for Ga 3d. The films were X-ray amorphous. Energydispersive X-ray analysis (EDXA) and electron probe microanalysis (EPMA) gave coherent elemental compositions, indicating that a single phase Ga 2 O 3 was made, with negligible impurity levels. The films showed little optical reflectance (∼10%) and 65-75% total transmission from 400 to 800 nm. Gas-sensing experiments indicated that the films responded best to a reducing gas at 450°C.
Proceedings Imcs 2012, 2012
Field effect Hydrogen gas sensor devices based on β-Ga 2 O 3 thin films with a function of temperature compensation were fabricated. β-Ga 2 O 3 thin films were deposited on sapphire substrate by gallium evaporation in oxygen plasma. Resistance between two ohmic electrodes on β-Ga 2 O 3 thin film with Pt gate was decreased in H 2 ambient. The sensor can detect 100ppm H 2 under 20%O 2 at 400 o C. The resistance of the device without gate little changes for an ambient variation. By connecting the devices with and without gate in series, the devices have a function of self temperature compensation. It was demonstrated that the device kept stable output even for temperature fluctuation over 100 o C.