Design And Simulation Of Heterostructure Mid-wavelength Infrared InSb-APD Detector

Infrared detectors have significant applications in the automotive industry,whether in the initial vehicle production and manufacturing or advanced automotive intelligent assistant technology.However,with the rapid progress of new energy vehicles to intelligence and assistance,there is an urgent demand for advanced infrared detectors.But the refrigeration demand of high-performance MWIR detector is still an important obstacle to its extensive application.For realizing uncooled infrared detection at room temperature,the heterostructure In Sb-APD detector with separated absorption,charge and multiplication layer(SACM)is designed.Using Silvaco-TCAD software,combined with semiconductor physical model and material characteristic parameters,the device is gradually modeled and simulated.Firstly,the heterostructure In Sb APD with separated absorption and multiplication layer(SAM),which based on P-type/intrinsic/N-type(PIN)structure,is designed and preliminarily simulated.The wide band gap semiconductor material is used as the upper and lower contact layer to form the double heterojunction.The optical absorption region is optimized with SAM structure.After selecting appropriate doping concentration through energy band engineering,the analysis show that electron and hole barriers are introduced on both sides of conduction and valence band respectively to inhibition the diffusion current and guarantee of the transmission of photogenerated carriers.The dark current analysis at room temperature shows that Auger recombination is significantly inhibited due to the carrier exclusion between the absorption layer and the multiplication layer under reverse bias voltage.The main generation mechanism of dark current is Schottky-Reed-Hall recombination,and the significant effect of band to band tunneling can be observed with higher bias voltage.At the same time,the influence of heavily doped absorption layer shouldn't be ignored.The gain of detector is severely limited by dark current.The specific detectivity is 2.866×10~9 cm·Hz^1/2W^-1.Secondly,for improving the performance of detector,the effects of diverse structural type on the property is researched.The larger doping concentration of absorption layer leads to a lower dark current,but the photoresponsivity significantly reduced;as the absorption layer thickness enlarging,the switching characteristics are promoted,but the photoresponsivity tend to up then down.With larger residual doping concentration of the multiplication layer,the transient response deteriorates suddenly,and the depletion layer narrows,and the built-in electric field is unevenly distributed,and the avalanche ionization process is limited.With the thickening of the multiplication layer,the photoresponsivity improves and the junction capacitance lessens,but the dark current increases and the transient response begins to deteriorate.The punch-through voltage of the detector is positively correlated with the thickness of the multiplication layer,but the breakdown voltage is negatively correlated when the thickness is thin.The effect of N-type contact layer is slight,indicating that the trifling influence of carrier extraction at that region.Meanwhile,the structure of unintentionally N-type doped I region(P?N)has lower onset voltage and saturated dark current,which is a reasonable choice.Finally,based on the research,the charge layer regulating the internal electric field of the device is introduced to form the SACM structure.The results of photoelectric performance analysis show that increasing the doping concentration of charge layer is conducive to the internal electric field regulation,but the switching characteristics of the device deteriorate sharply at a larger doping concentration;The thicker charge layer effectively controls the electric field intensity of the absorption layer and differentiates it from the multiplication layer,but the dark current increases significantly and a higher external bias voltage is required for operation.The thin and heavely doped charge layer can rise the punch-through voltage up and control the breakdown voltage,while avoiding the breakdown of the absorption layer before getting punch-through.The punch-through and the breakdown voltage of prepared detector is12 V and 72 V,respectively.When the device operates in linear mode,the gain increases to 20.The maximum photocurrent of SACM structure increases,but the recovery time increases;the maximum photoresponsivity is 3.06 A/W,and the external quantum efficiency at the peak is67.6%,but the 5.6?m peak position of photoresponsivity does not change.The specific detectivity is 4.473×10~9 cm·Hz^1/2W^-1.