Characteristic Research And Test Optimization Of Silicon Drift Detectors

SDD(Silicon Drift Detector)is a kind of semiconductor detector based on the principle of lateral depletion.SDD is equipped with a small area n~+anode to collect signal electrons in a large detection volume.Small readout capacitance(?60f F)can be obtained regardless of the detector area.Reasonable drift time(<100ns)can achieve2D position sensitive detection,Ultra-high energy resolution without liquid nitrogen refrigeration(128ev@55Fe).Based on these characteristics,silicon drift detector has attracted much attention in the field of X-ray spectroscopy and imaging,and has been widely used in X-ray fluorescence analysis,astrophysics,high-energy physics,medical imaging and other fields.Combined with these features,SDDs has attracted much attention in the field of X-ray spectroscopy and imaging,and has been widely used in X-ray fluorescence analysis,astrophysics,high-energy physics,medical imaging and other fields.It is hoped that our research work will provide a useful attempt for the independent development of the country's silicon drift detector.The main contents of the thesis are as following:(1)Through theoretical analysis,the working principle of SDD is mastered.Based on the interaction between X-ray and semiconductor and the principle of lateral depletion of detector,the process of electronic signal drift diffusion and anode reading in silicon drift detector is studied.Silvaco simulation tool was used to constructed concentric drift ring and multi-protection ring structure of SDD,meanwhile,the leakage current,potential electric field distribution and electron concentration distribution were simulated,the influence factors of the charge drift path were analyzed,the protection ring and optical response characteristics wrer verified,and the device characteristics wrer simulated.(2)The fabrication of SDD was completed,the electrical characteristics were tested and the key electrical parameters were analyzed.The dependence of leakage current bias and protection ring bias is studied,and the influence of inner ring bias on device performance is analyzed.The anode leakage current is successfully reduced to0.2n A,the device reverse breakdown voltage is increased to-200v,and the drift ring design is optimized with a ring width of 70?m and a ring spacing of 30?m.The optimization of the transverse drift electric field is realized by simulating the built-in partial voltage resistor.(3)The wire bonding of silicon drift detector is realized,the laser pulse signal detection is successfully realized,and the clear pulse curve is obtained,which verified the laser response ability of silicon drift detector.