Research On The Characteristics Of ?–? Semiconductor Avalanche Photodiodes

Avalanche photodiodes?APD?have become important receivers in optical fiber communication system because of the advantages of high internal gain,low power consumption,small size and large operation spectrum.To meet the requirements of detecting light signals with different wavelength bands and adapting to different working environments,researchers have tested APDs of various materials,therefore,APD based on different materials have achieved significant developments.III-V semiconductors InP,InAlAs,as wide band-gap materials,they often formed heterojunction APD with the narrow band-gap semiconductor In_0.53Ga_0.47As.This kind of APD has the advantages of high gain and low noise,which has become a hot spot in current research.The III-nitrides represented by GaN,as wide bandgap semiconductors,have high thermal stability and chemical stability,which are commonly used to make ultraviolet photodetector devices and high power devices.This paper focuses on the working characteristics of III-V semiconductors infrared and ultraviolet APD.In view of the single photon avalanche diode?SPAD?with self-feedback mechanism,we simulate the change process of the band and electric field with time during the SPAD working process,and expound its working principle in detail.In addition,the relationship between the response time and the applied voltage is studied by calculating the variation of the output current of the SPAD under different bias voltage.We find that the applied voltage has an important influence on the response speed of the SPAD.In order to improve the excess noise characteristic of APD,an APD with multi-multiplication layer structure is proposed,which regulates the electric field distribution of the APD,and then affects the collision ionization probability of the carrier,to reduce the excess noise.In this paper,the spatial distribution of carrier collision ionization is calculated,and the internal process of avalanche effect is studied,which can help optimize device design.In addition,based on the traditional<G>-F model,the effect of the generation-recombination process and the surface leakage current on the excess noise factor is also studied.In this paper,the photoelectric properties of GaN based APD are simulated by numerical simulation and the radiation characteristics are studied.The SRIM software is used to simulate the process of different energies protons irradiation on the device.The vacancy density of Ga atoms and N atoms produced by irradiation and the relationship between the non-ionization loss energy?NIEL?and particle penetration depth are obtained.According to the simulation results of SRIM software,the effect of proton irradiation on the dark current degradation of GaN APD is also calculated.