The Study Of In InGaAs/InP Avalanche Photodiode Single Photon Detector

Avalanche photodetectors(APDs)can weak light signals detection due to its capacities of high gain and high detection efficiency in Geiger mode.Therefore,avalanche photodetectors have a wide range of applications in civil and military fields.However,the non-negligible dark current limits high-performance devices in Geiger mode.At present,the most of research on dark current of avalanche photodetectors are verifying classical theoretical in experiments,which needs a long period and high price.Therefore,simulation is the common method of designing and optimizing devices.Here,we use sentaurus TCAD to establish simulation model to analyze the dark current mechanism of In Ga As/In P APDs.The influence of structural parameters on dark current are investigated in detail.In addition,combining the dark current mechanism and extracting the internal key parameters of the device,we establish theoretical model that can predict the photon detection efficiency and dark count of the device.The details content are as follows:1.The planar In Ga As/In P avalanche photodiode was numerically simulated,and the internal dark current mechanism was analyzed in detail.The effects of multiplication layer thickness,absorption layer thickness and minority lifetime on each dark current composition is discussed.The results demonstrate that the thickness of the multiplication layer has a great influence on band-to-band tunneling(BBT)and trap-assisted tunneling(TAT)dark currents.The BBT current decreases as the thickness of multiplication layer increases.The thickness of absorption layer dominates the thermal(SRH)dark current.The minority carrier lifetime can be equivalent to the trap concentration,which has a significant effect on the total dark current.Among them,the TAT dark current changes with the minority carrier lifetime in multiplication layer,while the SRH dark current is basically unchanged.Both the SRH and TAT dark currents vary with the change of the minority carrier lifetime in absorption layer.2.Based on the theoretical model formula of dark current and the internal parameters of the device,we proposed a theoretical model to predict the photon detection efficiency and dark count of the device.The results show that the photon detection efficiency is proportional to the thickness of the absorption layer,whereas increases firstly and then decreases with the increase of the thickness of the multiplication layer.The trade-off relationship between photon detection efficiency and dark count for different absorption layer thickness and multiplication layer thickness shows that,the dark count increases with the increase of absorption layer thickness at low photon detection efficiency.As the photon detection efficiency approaches the maximμm quantμm efficiency,the dark count increases exponentially.The multiplication layer has a great influence on the tunneling dark count.Under a certain photon detection efficiency,the smaller the multiplication layer thickness,the greater the dark count.3.Finally,the relationship between dark count and temperature under different absorption layer thickness,multiplication layer thickness,bias voltage,and the trade-off relationship between photon detection efficiency and dark count under different temperature are studied.The results show that the temperature can significantly affect the thermal SRH dark counts.Because the mechanisms of the dark counts change with different device parameters,the total dark counts have different trends under different parameters.In addition,the trade-off relationship between dark count and photon detection efficiency at different temperatures shows that,the dark count changes significantly with the increase of photon detection efficiency at low temperature,while the dark count changes less with the increase of photon detection efficiency at high temperature.