Study On Solar-Blind Position Detectors Based On Ga₂O₃

Due to the strongly absorbed and scattered by the ozone layer,water vapor in the atmosphere,and small particles,light with a wavelength less than 280 nm in solar radiation is almost non-existent on the earth's surface,so it is called the solar-blind ultraviolet band.The solar-blind ultraviolet band provides a low background detection window for accurately detecting unnatural light.Therefore,solar-blind ultraviolet photodetectors have the advantages of high detection rate,fewer interference factors,and low false alarm rate.They can be widely used in biological/chemical analysis,security communications,missile guidance and guidance,laser alignment and other fields.At present,solar-blind photodetectors are mainly made of some ultra-wide band gap semiconductor materials,such as Zn_xMg_1-xO,Al_xGa_1-xN,?-Ga₂O₃and diamond.As a typical wide-band gap semiconductor material,?-Ga₂O₃has a band gap between 4.4 e V and 5.1 e V,and the absorption is located in the solar-blind region.It has intrinsic solar-blind/visible characteristics,high thermal stability and chemical stability,High breakdown field strength,high radiation resistance and many other excellent characteristics,so it can be used to detect solar-blind light.?-Ga₂O₃solar-blind photodetectors are currently widely studied,but the reported solar-blind photodetectors can only detect the intensity of solar-blind light,and cannot give the location of the solar-blind signal source.However,in the military and civilian fields,there are many application requirements for solar-blind light position detection,such as solar-blind light alignment,real-time position detection,distance measurement,and so on.Therefore,there is an urgent need to realize solar-blind ultraviolet position detectors based on wide band gap semiconductor materials.In this article,we have developed a detector based on?-Ga₂O₃that can be used to detect the position of solar-blind spots.The main results obtained so far are as follows:(1)Four-quadrant position detector based on?-Ga₂O₃film:?-Ga₂O₃film is deposited on sapphire by plasma enhanced chemical vapor deposition,and then a four-quadrant position detector is prepared by photolithography and other techniques.The response peak of the four-quadrant position detector is located at 243 nm,the cut-off wavelength is 263 nm,and the ultraviolet/visible suppression ratio is about133,which can be used to detect the quadrant where the solar-blind spot is located.Finally,we built a solar-blind spot detection system based on the four-quadrant detector to realize the positioning and alignment of the solar-blind spot.(2)?-Ga₂O₃/polycrystalline diamond two-dimensional position sensitive detector:In order to achieve continuous detection of the position of the solar-blind spot,we have fabricated a solar-blind two-dimensional position sensitive detector based on?-Ga₂O₃/polycrystalline diamond.The preparation method is as follows:firstly,a?-Ga₂O₃film is deposited on a polycrystalline diamond substrate by plasma enhanced chemical vapor deposition,and then a?-Ga₂O₃/polycrystalline diamond position sensitive detector is prepared by photolithography.The position sensitive detector has good light response characteristics,with two response peaks located at220 nm and 245 nm,which can accurately and continuously detect the position of the solar-blind spot.