Design And Fabrication Of In InGaAs/InP Single Photon Avalanche Photodiode Arrays

The technological development of quantum communication,LIDAR and other fields has put forward higher and higher requirements for detectors,and single photon detectors capable of detecting single photon energy have become a current research hotspot.Among them,single photon avalanche photodiodes have the advantages of high detection efficiency,fast time response,and the ability to realize high-integration large-area imaging,making it one of the most promising single photon detectors.This thesis mainly focuses on the research and discussion of InGaAs/InP SPAD devices applied in the near-infrared band.We successfully designed and fabricated a 64×64array device and tested its performance parameters.The specific work of the thesis is as follows:Using TCAD,a planar back-illuminated InGaAs/InP SPAD pixel structure with SAGCM architecture was designed.Through the optimization of various parameters such as layer thickness and doping concentration,theoretical modeling and simulation of the 64×64 InGaAs/InP SPAD array device were completed.The optical and electrical performance parameters,such as I-V characteristics,electric field distribution,photon detection efficiency,and avalanche breakdown probability of the device were obtained.The results show that the breakdown voltage has a linear relationship with temperature,and when the operating temperature was 255 K,the device’s breakdown voltage was 69.5 V.The response wavelength range of the device was 950 nm-1650 nm,and the peak detection efficiency at 5 V excess bias voltage was greater than 25%.In response to the impact of avalanche breakdown probability on the photon detection efficiency of the device,a key focus of the study was the relationship between the two Zn diffusion parameters and the avalanche breakdown probability of the device.It was found that under the same excess bias voltage conditions,with fixed deep diffusion depth,the deeper the shallow diffusion depth,the higher the avalanche breakdown probability in the center of the multiplication region.The larger the lateral diffusion factor of the Zn diffusion,the higher the avalanche breakdown probability in the center of the multiplication region and the lower the edge avalanche breakdown probability will be.Under the condition of constant diffusion depth,the shallow diffusion Zn doping concentration has no significant effect on the avalanche breakdown probability,while the higher the Zn doping concentration of deep diffusion,the lower the avalanche breakdown probability.A 64×64 InGaAs/InP SPAD array device was fabricated.SEM testing showed that the deep diffusion depth was 2.77μm,the shallow diffusion depth was 2.53μm,and the thickness of the multiplication layer was 0.3μm,which was lower than the theoretical design of 0.7μm.This difference could lead to a decrease in the breakdown voltage of the device.PL spectroscopy testing showed that the bandgap width of the In Ga As material at the center of the wafer was 0.75 e V,which was consistent with the theoretical design.The I-V characteristics,dark count rate,spectral response,and array uniformity were tested.The results showed that the breakdown voltage and dark current decreased with decreasing temperature.When the operating temperature was 233 K,the breakdown voltage of the device was 45 V,and the dark count rate of the device under 1 V excess bias voltage was 16 k Hz.Spectral response testing showed that the device had good response in a wide spectral range of 900nm-1650 nm,which was consistent with the theoretical design.Finally,the dark current and breakdown voltage of 134 pixels in the 64×64 array device were randomly tested,and the results showed that 95%of the pixels had a breakdown voltage between 52 V-53 V,with a difference not exceeding±1 V,indicating that the breakdown voltage of the device had good uniformity.The dark current was distributed between 10^-8A to 10^-6A,indicating that the uniformity of the dark current still needs further optimization.This thesis can provide a reference for the development and application of large-scale InGaAs/InP SPAD array devices.