Indium Oxide And Gallium Oxide UV Detectors And Flexible Applications

Ultraviolet(UV)detectors have low device background noise,low false alarm rate and high sensitivity,are widely used in civil and military fields such as industrial production,health protection,and missile warning.In2O3(3.7 eV)and Ga2O3(4.8 eV)have the advantages of wide bandgap and stable physical and chemical properties,are suitable materials for manufacturing UV detectors.In particular,Ga2O3 is an ideal material for solar-blind ultraviolet detectors due to the ultra-wide bandgap deep into the UV-C,which can shield the background radiation in the atmosphere.However,metal oxide semiconductor UV detectors still have slow response speed and insufficient detection selectivity,which limit their commercial applications.After years of development,advanced UV detectors require excellent mechanical properties to cope with complex working environments in addition to excellent photoresponse performance.Flexible UV detectors that combine flexible electronics and UV detection technology have become an important issue.Based on the above problems and requirements,this article focuses on two metal oxide semiconductor materials,In2O3 and Ga2O3.The response speed and selectivity of the UV detector are improved by reducing the defects in the film through doping elements that are more strongly combined with oxygen or oxygen annealing.What’s more,we developed high-performance flexible metal oxide thin film UV detectors.The main research contents of this paper are as follows(1)The solution method has the advantages of low cost,large scale and simple operation.The In2O3 thin film was grown on quartz and PI substrates by the sol-gel combustion method,and the In2O3 UV detector of the metal-semiconductor-metal(MSM)structure was fabricated.The rigid In2O3 UV detector has a high responsivity of 720 A/W and a photo-dark current ratio of about 7×104,but the response speed is slow.The 5%Mg doping optimizes the rise time from 27 s to 6 s and fall time from 52 s to 2 s,respectively.The flexible 5%Mg-doped In2O3 UV detector is fabricated on PI substrate.When the bending radius increases,the photo-dark current decreases but the photo-dark current ratio and response speed are basically stable.After multiple bends,the photocurrent has good stability.(2)We used pulsed laser deposition to grow β-Ga2O3 thin film on F-mica,and fabricated a flexible solar-blind UV detector.After increasing the growth temperature,the photo-dark current ratio and the UV-C-to-visible rejection ratio of the UV detector are effectively improved.The photo-dark current ratio,the responsivity at the wavelength of 230 nm,and the UV-C-to-visible rejection ratio of the detector based on the β-Ga2O3 film grown at 650℃ is 380,910 and 0.84 A/W respectively.After oxygen annealing,the photo-dark current ratio and UV-C-to-visible rejection ratio of β-Ga2O3 solar-blind UV detector improve to 9×103 and 8.1×104,respectively.The oxygenannealed β-Ga2O3 solar-blind UV detector has strong selectivity to solar-blind irradiation.The flexible β-Ga2O3 solar-blind UV detector has good photoresponse stability under bending conditions.The photoresponse performance and the response speed of the detector remain stable under different bending radius and times.