| Ultraviolet(UV)detection technology and infrared detection technology originated in the 1950s,while ultraviolet detection technology wasn't widely used because of the long time failure to solve the problem of low sensitivity.Until an avalanche multiplier was developed in Japan in 90s,UV detection technology finally got more attention in the field of camera devices due to its high sensitivity and suitable spectral range.Nowadays,ultraviolet detection technology has been widely applied in the fields of photoelectric communication,disaster warning,guidance and other military or civilian applications.Photoelectric detectors refer to the detectors which are capable of converting optical and other electromagnetic radiation to processable electrical signals.The devices used in this paper are all devices working in ultraviolet band,including avalanche photodiodes(APDs)and arrays,and the PIN diode array.Because the direct output signal of photodetectors is generally weak or hard to recognize due to the irregular shape of the waveform,we need to enlarge and reshape the signal through specific circuits for further processing or recording in actual applications.In particular,for APD devices which work in Geiger mode,once an avalanche strikes,the APD is not able to stop the avalanche event spontaneously.In order to prevent the device from burning out under a large current and to carry out continuous detection,a corresponding peripheral circuit,that is,quenching circuit,is necessary.The quenching circuits can be divided into passive,active and gated quenching circuits according to the quenching principles.In this paper,we developed two sets of single photon detection modules based on APD devices and passive/active quenching circuits.With the cooperation of Southeast University,system-level function verification is carried out for both single device and 1×8 array.Processing and analysis of the obtained data is carried out.As for PIN devices,our main work is to fabricate and characterize of a 320×256 GaN-based PIN detector array,as well as to conduct process optimization.With the same processing condition,320 X 256 Micro-LED arrays are fabricated.Detailed characterization of electrical and luminous properties is carried out.The following are the main results of this work:1.Based on existing TO packaged APD devices,passive and active detection modules were developed using analog circuit technology.The detection rate of passive single photon detection module reaches 100kHz,and the signal-to-noise ratio(SNR)is controllable up to 60-70dB.The active module has been upgraded with a high voltage power supply,device failure protection and counting functions,which has relatively higher detection efficiency and better SNR.The counting performance and detection efficiency of the APD inside the module have a certain degradation,which is likely caused by some current signal noise generated by the module circuit.2.Based on existing APD and linear array devices made by our laboratory and read-out circuit made vy our collaborator,the normal functions of the UV imaging system based on a single device or a 1×8 linear array are verified.The main problems being solved are to reduce dark counts of the APD as well as to improve reliability of the packaging scheme.With the help of these improvements,we successfully imaged a point light and a point light pair using the 1×8 APD linear array,which lays the foundation for the next step of work.3.320×256 PIN UV detection focal plane array and Micro-LED array are fabricated.The UV detection focal plane array shows normal opto-electrical characteristics,and its forward characteristics are improved after ohmic contact optimazations.We also tested the electrical and optical properties of the Micro-LED array.The electrical characteristics among pixels show high consistency,but the droop effect is not improved as we expected.In reliability test,the LED pixel still has 156 h lifetime under 3.2kA/cm2 stress,which can meet certain application requirements. |
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