| Single photon detection technology has broad application prospects in the fields of national defense military,scientific research and civil life,such as key distribution in quantum communication,laser ranging in astronomy,and fluorescence lifetime imaging in medicine.The short wave infrared InGaAs avalanche photodiode is a single photon detector that utilizes the internal photoelectric effect to amplify the optical signal by an avalanche multiplication mechanism.It has the characteristics of all solid state,small size,low power consumption,and no need for ultra low temperature refrigeration and has become one of the research hot spots.In this paper,two new device structure were designed based on the deep analysis of the absorption,graduation,charge control and multiplication separation structure of InGaAs avalanche photodiode.A series of studies were carried out using Silvaco Atlas simulation software,and the time-to-digital converter module has been designed.Then the main work are as follows:First,we proposed a novel InGaAs/InP avalanche photodiode with triple-mesa structure to eliminate the edge breakdown and reduce the dark current of conventional InGaAs/InP avalanche photodiode.The effects of various parameters on linear and geiger mode has been investigated by using Silvaco Atlas.The results shown that the edge electric field was 2.6×105V/cm which was a half of central electric field.The dark current reduced to 9.25pA at 0.9Vbr,which was one third of the traditional two-stage mesa device.What's more,the highest detection efficiency reach 37%,when the excess voltage was 5V at gating control mode.Second,an extended wavelength InGaAs/InP avalanche photodiode with an absorber layer added to the In0.66Ga0.34As/InAs superlattice barrier was designed to reduce the dark current while ensuring the photocurrent of the device,and the energy band theory was explained clearly.The superlattice barrier reduces the mechanism of dark current.The results show that when the reverse bias voltage is 35V,the dark current of the device is reduced from 2.2×10-9A to 2.89×10-11A.This result proves that the design was correct and reasonable.Third,a two stage time to digital converter was proposed for the application on low light detection.Then the coarse time counter module,fine time counter module,memory module and serial communication module were designed by using Verilog hardware description language.Then all of the modules were verified by using Modelsim software. |
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