Design And Simulation Of Multiplication Type In_0.83Ga_0.17As Photodetector

The mutual integration of industrialisation and basic digitalisation has led to the widespread use of optoelectronic devices in smart cars,the aerospace industry and fibre-optic communication systems and other related fields,and in the current era of exponential development of industrial and basic digital transformation,which puts forward more demanding requirements on the working characteristics of optoelectronic devices,and the photodetectors used in the automotive industry play a very important role in the development of smart cars in the process of photoelectric signal conversion.Therefore,the development and research of photodetectors in the automotive industry plays a very important role in the development of intelligent vehicles.In this paper,we mainly focus the infrared avalanche photodetector for automotive industrial auxiliary systems as a starting point,with the aid of the simulation tool Silvaco-TCAD,we combine the basic operating principles with further systematic study of structural design of the device,the optimisation of the each epitaxial layers and the performance simulation.Firstly,the SAM（Separate Absorption and Multiplication）type photodetector is designed to solve the problem of mutual trade-off between absorption efficiency and response speed caused by the thickness of traditional PIN type photodetector,and simulate effect of the doping concentration and temperature of the multiplication layer on the device performance.In addition,the simulation results show that the doping concentration of the multiplication layer has significant effect on the dark current and transient response of the device at 2×10¹⁶ cm^-3,but has small effect on the responsivity,so as to determine the optimal doping concentration of the multiplication layer,and further theoretical verification of the specific detectivity at this doping concentration value,its value is 1.948×10⁹ cm·Hz^1/2W^-1.In addition,the effect of temperature between 160-300 K on the device performance was investigated.The dark current density is 0.485 A/cm² at 300 K and-500 m V,and the peak values of differential resistance area and responsivity at wavelength 1.5μm are 0.053Ω·cm² and 1.818 A/W,respectively.Secondly,on the basis of SAM-type photodetector,the thickness and doping concentration of each epitaxial layer are simulated and analyzed comprehensively,then the optimal structural parameter values of each epitaxial layer are determined.The simulation results show that the responsivity of the device increases significantly after stripping substrate,reaching 1.498 A/W at wavelength 1.5μm.Meanwhile,the influence of structural parameters of the buffer layer,absorption layer and contact layer on the dark current,responsivity and transient response is investigated through simulations,and the results are analyzed comprehensively to determine the optimal structural parameters of the buffer layer,absorption layer and contact layer.The results are used to determine the thickness and doping concentration of buffer layer,absorption layer and contact layer,and to lay the foundation for the rational design of the new multiplicative SACM（Separate Absorption,Charge and Multiplication）type photodetector.Finally,based on the design and comprehensive analysis of the SAM-type device in the paper,a new multiplicative SACM photodetector is designed,focusing on the punch-through voltage and breakdown voltage of the designed device for further study.The simulation results show that the device of punch-through voltage at 10 V and breakdown voltage at 50 V.The concentration of the highly doping multiplication layer causes increase in capacitance and non-uniform electric field distribution,while the increase in its thickness causes linear increase in the punch-through voltage,but the breakdown voltage turns at 1.0μm and achieves minimum value at 44 V.The combination of the multiplication factor and the electric field distribution is used to explain the various.The spectral characteristics and transient response as well as the alternating current small-signal characteristics are also analyzed.In addition,the increase of charge layer doping concentration causes overall difference between breakdown voltage and punch-through voltage to decrease,but the punch-through voltage increases linearly and the breakdown voltage decreases linearly with the increase its thickness,and responsivity of the multiplicative SACM-type photodetector is improved.At the same time,the response time and switching characteristics are further improved.