Research On Solar-blind Photodetector Arrays Based On Sn-doped Ga₂O₃ Microwires

Although ultraviolet radiation accounts for only less than 10%of solar radiation,it has a profound impact on the production and life of mankind.Due to the absorption of ozone layer and atmosphere,solar radiation in the range of 200-280nm cannot reach the earth’s surface,so it is called solar-blind band.Photodetectors with response cutoff wavelength below 280 nm are called solar-blind photodetectors.Because it is not affected by solar-blind radiation,it has the unique advantages of high signal-to-noise ratio and low false alarm rate,and has a wide range of application prospects in communication,ozone hole monitoring,flame monitoring,chemical biological analysis and other fields.Ultra-wide bandgap semiconductors,including Zn_xMg1-x O,Al_xGa1-x N,diamond and gallium oxide（Ga₂O₃）,are usually employed to fabricate solar-blind photodetectors.Among them,Ga₂O₃ with a band gap of 4.4-5.1e V,corresponding to wavelengths of 243-280 nm in the solar-blind region,is considered an ideal choice for solar-blind detection and has been extensively studied in recent years.Compared with bulk or thin-film materials,the micro/nanostructure of semiconductors has unique optical and electrical properties due to their large surface to volume ratio,high crystal quality,and anisotropic geometry.Currently,photodetectors based on Ga₂O₃ microwires have been investigated,which exhibited extremely low dark current and high on/off ratio,but its performance still needs to be further improved.In addition,Ga₂O₃ microwires are usually randomly grown on the substrate,thus are difficult to realize controllable arrangement and integration of optoelectronic devices.Fabrication of solar-blind photodetector arrays requires a method to assemble Ga₂O₃ microwires in large area.In view of the above problems,this study aims to fabricate high-performance solar-blind photodetector based on Ga₂O₃ microwires and realize the Ga₂O₃ microwires photodetector array.The main results obtained are as follows:（1）Solar-blind photodetectors were obtained from Sn-doped Ga₂O₃ microwires grown by a chemical vapor deposition（CVD）method.The Sn-doped Ga₂O₃microwires have high crystal quality and a length as long as 1 cm.A solar-blind photodetector was prepared using the Sn-doped Ga₂O₃ microwires,and its photoelectric properties were characterized.The results show that the photocurrent of the Sn-doped Ga₂O₃ microwires is increased by about five orders of magnitude compared with that of undoped Ga₂O₃ microwires.The photodetector based on Sn-doped Ga₂O₃microwires showed high photoresponse performance with a light/dark current ratio of about 10⁷,and a responsivity of about 2409 A W^-1 at 40 V.The solar-blind rejection ratio of the device is 41.4,the UV/visible rejection ratio exceeds 3 orders of magnitude,the cut-off wavelength is 268 nm,and the rise time is only 7.9 ms,indicating that the photodetector has high spectral selectivity and fast response speed to solar-blind UV radiation.（2）Solar-blind photodetector arrays were fabricated from the Sn-doped Ga₂O₃microwires via a patterned-electrodes method.A linear array of 1×10 solar-blind photodetector was prepared by transferring the Sn-doped Ga₂O₃ microwires onto a prefabricated patterned electrodes substrate.The performance of 10 photodetector units is characterized,and the results show that the light/dark current have good uniformity,and the periodic test also shows good stability,indicating that each photodetector unit could work independently as a pixel.By building a solar-blind imaging system and using the 1×10 linear array as a sensor unit,solar-blind imaging of different patterns is realized.