Analyses On Dark Current Components Of Infrared Avalanche Photodiode And Its Mechanism Research

Compared with other optoelectronic devices,avalanche photodiode(APD)has the following advantages: high quantum efficiency,high detection efficiency,stable structure,wide wavelength coverage,fast detection speed,etc..APD based avalanche devices have been widely used in many military and civilian applications.Along with the third generation infrared imaging detector concept,research for high performance avalanche device with low noise,low cost,high sensitivity,high temperature is becoming the main target of the development of the third generation infrared imaging detector.At present,the main problem of APD is that it has huge dark current,and the carrier transport and optical gain generation mechanism of the device still remian unclear.In view of this,this paper successfully use the Sentaurus-TCAD simulation softwareto model and simulate the InGaAs and MCT APDs.By using theoretical analysis we could provide theoretical guidance and structural optimization to the device fabrication,and thus effectively reduce the development period and cost and improve the performance of the device.Details are as follows:1.The components of dark current in SAGCM InGaAs/InP APD were extracted by numerical simulation,and the results proved that SRH current dominants the total dark current.Then,the influence of the recombination center in the InGaAs absorbing layer on the dark current is theoretically calculated and analyzed.The results show that the dark current characteristics of the device are obviously limited by the concentration and the position of the composite center.In addition,the relationship between the minority carrier lifetime and the dark current is analyzed,and the results can be used to estimate the minority carrier lifetime of the device.2.The two kinds of structural performance of mesa and planar junction HgCdTe e-APD had been analyzed by numerical simulation,and the results proved that the dark current characteristics were greatly influenced by the built-in electric field.What's more,the dark current and gain of the device can be optimized by changing the thickness of the multiplication region,and so appropriate structural parameters should be selected according to the working condition requirements.Finally,the analysis of the local electric field at the planar junction corner shows that the dark current can be reduced effectively by improving the farbrication technology to reduce the sharp angle of the junction.At the same time,the results of the analysis of mesa junction show that the dark current characteristics are greatly affected by the doping concentration in the multiplier region.The research results can be used to guide the design and optimization of APD HgCdTe device.