Numerical Simulation Of InP/InGaAs APD

With the rapid development of quantum communication technology and the demand for near-infrared single-photon detectors in military and civilian applications,the study of single-photon detectors has become particularly important.This thesis research on the SAGCM structure(separate absorption layer,graded layer,charge layer,multiplier layer structure)InP / InGaAs avalanche photodiode(APD).Because of the fact that the cost of manufacturing devices is high,the yield rate is low,and it takes a long time,the simulation of its structure and performance before the manufacture of actual devices can greatly save resources and improve it's efficiency as well.In this paper,the device model is established based on the continuity equation of carrier and Poisson equation,and the device characteristics are analyzed with the numerical calculation(such as layer thickness,doping,minority carrier lifetime and guard ring et.).A systematic theoretical simulation of the device was carried out,which generalize to a series of low that would instruct the actual growth of device.In this paper,the Cosslight's APSYS semiconductor simulation software is used to simulate the InP / InGaAs avalanche photodiode.Based on the drift-diffusion model,the Poisson equation and the current continuity equation are solved by self-consistent method.In such way,we got the accurate simulation results to optimize the device.After the reliability of APSYS is verified,we work on the following research:1.Use APSYS software to study the influence of the charge layer and multiplication layer parameters of the device to the APD.The result shows that as the charge density of the charge layer increases,the APD breakdown voltage decreases linearly,and the penetration voltage is increases linearly.The function of the charge layer is mainly due to the change density of this layer will adjust the electric field distribution of the absorption layer and the multiplication layer,thereby affecting the magnitude of the breakdown voltage and the penetration voltage.With the thickness of the multiplier layer increases,the breakdown voltage first decreases rapidly and then slowly increases.While the penetration voltage is sub-linear increases.2.Theoretically analyze of the influence of the minority carrier lifetime of each layer of SAGCM InP / InGaAs avalanche photodiode to device dark current is studied.The result shows that the magnitude of the dark current before device is penetrated mainly affected by the multiplier layer minority carrier lifetime,which decreases with the increase of the multiplier layer minority carrier lifetime,and such effect will decreases as the bias voltage increases.With the applied bias voltage is over the penetration voltage,there will be a step of dark current surge,the main reason is that the minority carrier lifetime is decreased in the absorption layer.3.Through theoretical analysis of the position,width and depth of the protection ring,a more complete rule is explored to guide the growth of the planar structure of the APD protection ring.