Research On The Key Technologies Of The Third Generation Antimonide-based Infrared Detectors

With the requirment for infrared technologies of high performance and low cost,third-generation infrared detectors are being developed which,in the common understanding,provide enhanced capabilitiessuch as higher detectivity,larger numbers of pixels,low cost,and multicolorfunctionality.Antimony-based infrared detectors,such as InSb infrared detectors and InAs/GaSb type ? superlattice,has become main competitors of third-generation infrared detectors,due to their excellent physical characteristics and the mature technologies of ?I-V componds.It is of great importance to design and fabricate high performance and low cost ?I-V infrared detectors.The performance of InSb infrared detectors has been being improved for several decades.The surface passivation has become the main restraint factors ofInSb infrared detectors with large format and small pixel.The influence of interface traps on the transient characteristics,the steady-state characteristics,and the dark current characteristics of a back-illuminated photovoltaic InSb infrared detector were studied using Silvaco-ATLAS.And the results were analyzed in detail.The work done in this paper are shown as follows:1.The 2-D numerical model based on physical models of a back-illuminated photovoltaic InSb infrared detector was built on the Silvaco-ATLAS platform.The physical process was studied of the InSb infrared detector under illumination,such as the generation,diffusion,and combination of photon-generated carriers,the transport and the collection of minority carriers,and the current-transport characteristics.The working mechanisms of theinfrared detector chip were analyzed and the impact of the structure and the process parameters on the performance of the detector were studied.2.The physical models of the InSb infrared detector chip were modified considering the impact of donor-like interface traps on the performance of a back-illuminated photovoltaic InSb infrared detector.The influence of interface traps on the transient characteristics,the steady-state characteristics,and the dark current characteristics of a back-illuminated photovoltaic InSb infrared detector were studied using Silvaco-ATLAS.The influence of interface traps on the quantum efficiency,the crosstalk and the transient response were analyzed in detail.The“black holes”in the current density distribution was found for the first time and its formation was analyzed.Antimony-based type ? superlattice infrared detectors,such as InAs/GaSb,have become excellent candidates for third-generation infrared detectors,due to their excellentphysical characteristics and the mature technologies of ?I-V componds.However,the potential of InAs/GaSb type ? superlattice infrared detectors has not been fully developed.A 128×128 short-wavelength infrared detector using MBE grown Type-? InAs/GaSbsuperlattice was reported,in which the passivation process was optimized.The work done in this paper are shown as follows:1.200 period 4MLInAs/8ML GaSbtype-?superlattice was grown by molecular beam epitaxy on n-type doped?100?GaSb substrates.The thickness of one periodwascalculated to be 3.97nmclose to the designing value 3.66nm.A tensile stress was observed in the superlattice film.Lattice mismatch between the SL and the GaSb substrate was0.33%.Photoluminescence peak wavelength was 2.88?m at 77K.The PL results show that the temperature dependence of our InAs/GaSbtype-?superlattice is low,which means that the working temperature of the InAs/GaSbtype-?superlattice detector is higher than its MCT counterpart.2.A 128×128 short-wavelength infrared focal plane using the MBE grown type-? InAs/GaSb superlattice was made,and clear images were obtained.The pixel of the arrays consisted of a conventional PIN structure with a size of 42?m×42?m.Distance between adjacent pixels was 50?m.Mesa structure was used to minimize the cross-talk between pixels.Typical backside illumination geometry was selected.At 77K,the detector showed a peak response wavelength of 2.8?m and a peak detectivity of 1.3×10¹11 cmHz^1/2W^-1,with a R₀A value of 2.0×10⁶?×cm²and a quantum efficiency of 35%.Its operability was better than91%and its response dispersion less than 10%.3.Elemental crystals,formed by oxidation of InAs and GaSb,increase the surface roughness,and introduce surface state,which increases both the nonradiation combination of the surface and the dark current.Thus,surface passivation is one of the most important steps in the fabrication of an FPA,and we tried to optimize the process.Four passivation methods,?i?anoide sulfide followed with Zn S deposition,?ii?SiO₂passivated,?iii?,SiN_xpassivated and?iv??NH₄?₂S chemical passivated with ZnS deposition,were tested.And the best one,anoide sulfide followed with ZnS deposition,was selected.