| Avalanche photodiode?APD?based on silicon carbide?Si C?has the ability to detect weak UV signal,which is a key component for many cutting-edge applications,such as corona detection,fire alarm,environmental monitoring,and missile plume detection and tracking.Compared with other semiconductors for making UV detectors,Si C material has low defect density and mature epitaxy technology.Si C APD has a response peak near 280nm and a response cutoff wavelength at 390nm,which means that the device is essentially non-responsive to visible light and has unique advantage in detecting solar-blind UV signals.Compared with traditional vacuum ultraviolet detectors such as photomultiplier tubes?PMT?,Si C APD has many advantages,such as small size,low cost,easy for integration and visible blindness.Therefore,Si C APD is good candidate in the field of weak UV signal detection,and has drawn worldwide attention.Although Si C APDs have been reported by several research groups,majority of them still do not have the capability of single photon detection.There are still many problems for the application of Si C APDs,such as high dark current,high dark count rate,low single photon detection efficiency and avalanche voltage variation.In order to find and solve the potential problems in application of Si C APDs,we conduct research based on the 4H-Si C APDs fabricated by our own research group,including crosstalk analysis of 4H-Si C APD linear arrays for UV imaging applications and corona detection system based on a single 4H-Si C APD.The main contents and conclusions are shown as below:1.Crosstalk study of Si C APD arrays for UV imaging application:the breakdown voltages of devices in a 1×128 4H-Si C APD linear array are collected by using a probe station and a high-performance oscilloscope.A program is designed to analyze time correlation of avalanche pulses.For the first time,the crosstalk probability of a 4H-Si C APD linear array is studied.It is found that the Si C APD array exhibits a crosstalk probability of 3%,which is similar to those of In Ga As/In P based APD arrays and Si-based APD arrays.At the same time,the main factors causing crosstalks are analyzed.Crosstalk events occur within 10ns for adjacent 4H-Si C APD devices with a 112?m pitch.The crosstalk probability decreases with increasing device distance,and increases with increasing device bias voltage.2.Corona detection system based on 4H-Si C APD:the APD detection circuits are designed,including filter modules,high-voltage power circuits,signal amplification and filtering circuits as well as analog-to-digital conversion circuits.The hardware circuits solve the problems of high voltage biasing and signal sampling.Then the signal data is collected and analyzed by FPGA,which implements functions like real-time display of ultraviolet light intensity,alarm function and wireless transmission.The performance of the detection system is tested by using simulated corona signal.The detection system can work stably and reliably indoor and outdoor.The system has high sensitivity of 85n W/cm-2,which responds to a corona detection distance of 10m.The detection signal can be transmitted wirelessly to various terminals for remote monitoring. |
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