Study On Properties And Preparation Of Tungsten Doped Vanadium Oxide Uncooled Infrared Detector

In recent years,uncooled infrared detectors have attracted more and more attention in commercial applications due to their advantages of low energy consumption and low cost.For uncooled infrared detectors,the researchers mainly concerned about two important issues,one is how to improve the properties of the thermal sensitive materials to achieve higher detection performance,the other is how to improve the process of the preparation of the detector,including the micro-bridge structure,so as to improve the thermal insulation.VOx has become the core material of microbolometer uncooled infrared detector,however,due to the simple composition and structure of pure vanadium oxide,more and more diversified demand for today's are difficult to meet,we can generally improve the performance by the way of doping.In this paper,the preparation process of microbolometer was discussed,W-doped vanadium oxide microbolometer and non W-doped vanadium oxide micro bolometer were prepared by magnetron sputtering,and then the resistance temperature characteristic and photoelectric response and noise characteristics were analyzed,the influences of tungsten doping to the micro bolometer were investigated.The main contents and achievements of this paper are summarized as follows:1.Tungsten doped VOx thin films and non W-doped VOx thin films were grown by DC magnetron sputtering.We obtain the resistors of tungsten doping vanadium oxide thin films at room temperature was 160K?,TCR value was-3.169%/K,the resistors of non W-doped vanadium oxide thin film at room temperature was 125 K?,TCR value was-3.105%/K.After the tungsten doping,the phase transition temperature of the device was reduced by about 16?,the width of thermal hysteresis was reduced by about 5°C,the responsivity of the device was improved,the maximum increase was about 52V/W,and the noise interference was reduced to some extent.2.Fabrication process was designed,using polyimide as the sacrificial layer,we have constructed a surface micro bridge structure with a 1*9 line of vanadium oxide micro bolometer using Si technology on the substrate.The best plan of fabrication of devices was explored,Si/SiO2/Si3N4/SiO2/Si3N4 was used as the support layer,thickness was 100nm/100nm/300 nm/100 nm/100nm respectively.The vanadium oxide thin films were annealed to prevent the fracture of the micro bridge structure after growing.The test results show that the detectivity of the device has a maximum value in a certain range,the detectivity did not increase with the increase of bias current.In this study,40?A was the peak of the detectivity.And when the temperature was 800?,the bias current was about 40?A,and the modulation frequency of the radiation signal was about 40 and 80 Hz,respectively,the detectivity of detector using tungsten doped vanadium oxide as photosensitive layer was 1.81×108 and 1.46×108cmHz1/2/W respectively,the detectivity of detector using non tungsten doped vanadium oxide as photosensitive layer was 1.72×108 and 1.37×108cmHz1/2/W.It can be seen that the detectivity of W-doped vanadium oxide detector is higher than that of non W-doped vanadium oxide detector.The above research shows that the structure of the microbolometer infrared detector can be used as the detector of high performance in the future,tungsten doping can effectively improve the performance of vanadium oxide film so as to improve the performance of detector.