Tungsten Oxide Gas Sensor
Tungsten Oxide Gas Sensor
There are many types of gas sensors, due to the variety of interaction forms between the gas and material, the reflected physical, chemical and biological effects or phenomena will be vary, thus will bring a lot of classification methods. Some are according to the type of gas (oxygen-sensitive, alcohol sensing and ammonia-sensitive devices etc.); some are according to the matrix material (metal oxide, organic polymer semiconductor and solid electrolyte type etc.); some are according to working ways (dry and wet method etc.); some are according to the structure type (sintered, thin-film and thick-film type etc.); and some are according to the working mechanism (resistive, capacitive, type diode characteristics, transistor characteristics frequency and electrochemical type etc.).
WO3 is an N-type metal oxide semiconductor material, its resistance changed when contacts with the gas to be measured, thus to realized the goal of detecting gas by changing the output signal. WO3 has good performance of selectivity and sensitivity for H2S, SOx, NOx and other gases, which makes it a very good prospect. The thin film deposition techniques and the corresponding deposition parameters of WO3 have great impacts on gas sensing properties of the film gas sensor. The density of defects in the thin-film will be varying depending on the different producing technologies and forming conditions; on the other hand, the particle size also changes during the heat treatment. All above aspects have a great impact on the tungsten trioxide electrical properties and gas-sensitive response.