Ultraviolet Light Enhanced Gas Sensor Based On Semiconductor Oxide Composite Materials

The main shortcoming of the traditional semiconducting metal oxides gas sensors is thatthe sensors are operated at high temperature. It not only costs extra heating power but alsomay lead to potential safety problems and cause undesirable long-term drift problems. Toobtain low-energy and intrinsic safe gas sensors operated at low temperature, UV light wasintroduced to activate the sensors.A novel thin film device structure was designed and increased the light utilization rateobviously. Pt electrodes were printed on quartz substrates by silk screen printing method.Sensitive materials covered the surface and were irradiated vertically by UV light source.ZnO-SnO₂thin films were prepared by Sol-Gel method, the gas sensitivity of the deviceswith and without UV light illumination was tested in static testing system. The device candetect ethanol under35℃. It confirmed that thess composite materials actually were suited toUV enhanced gas sensor.Then the structure of heterogeneous composite materials was designed. ZnO monocrystalnanorods were chosen to be optical active center. As gas sensing center, SnO₂nanoparticlescovered on them. On the one hand, specific surface area increases, and the efficiency of gasadsorption and desorption increases. On the other hand, the forbidden band width of SnO₂islarge, and it can be used as optical window.This composite material showed outstanding gas response and selectivity of NO₂detection at room temperature. What’s more, the optical excitation properties of ZnO arenoteworthy. ZnO nanoclusters allay thinfilms with hierarchical structure were prepared byCBD method. It also realized NO₂detection at room temperature.At last, heterostructure model and surface control model were proposed to explain themechanism of gas sensing properties under the UV light. It provided theoretical basis for theresearch of UV enhanced room temperature sensor.