Research On Structure And Luminescence Characteristics Of Type Ⅱ Superlattice Based On Quaternary Alloy

The medium and long wave infrared photodetectors are widely used,and have important strategic significance in the civil and military fields due to the particularity of the working band.Cadmium mercury telluride(MCT)bulk material is the most widely used material at present.However,with the continuous development of science and technology,under the demand driving force of the third generation of infrared detectors with large area array,high performance and low cost,the antimony-based narrow band gap II superlattice material based on "energy band engineering" has attracted extensive research interest.The theoretical prediction has the advantages of flexible and adjustable band gap,high quantum efficiency and low Auger recombination rate,and is expected to replace the Hg Cd Te material as the best candidate material for the third generation of medium and long wave infrared detectors.A variety of superlattice focal plane devices with different specifications and different detection bands have been realized internationally.However,with a further understanding of its photoelectric properties,the existing shortcomings also gradually appear.Short minority carrier lifetime and high non-radiative recombination lead to a low signal-to-noise ratio and large dark current of the device,which has become the main problem limiting practical application and performance improvement.Therefore,we should find a breakthrough point in the development of new materials,prepare multilayer superlattice materials with high crystal quality,long minority carrier life and large absorption coefficient,and open the golden era of superlattice infrared detection research.Currently,a new based on quaternary alloy of InAs/InGaAsSb type II superlattice(T2SL)material has been proposed.However,the research on this superlattice material system is still not perfect,and strong experimental evidence is still needed to verify its potential superiority.Based on the above situation,this paper systematically and detailedly demonstrates its structural characteristics and luminous characteristics.The specific research contents are as follows:1.Research on the structure of InAs/InGaAsSb T2 SL crystals.The influence of In Ga As Sb layer thickness change on the crystal surface interface structure in InAs/InGaAsSb T2 SL was studied.The epitaxial materials were characterized by XRD and AFM techniques,and the mechanism of strain balance control and the factors affecting the crystal quality were analyzed.The interface structure was studied by transmission electron microscopy.The relationship between the interlaminar stress distribution and the crystal structure is analyzed by using geometric phase analysis(GPA).2.Research on luminescence characteristics of InAs/InGaAsSb T2 SL crystals.The transmission spectrum and photoluminescence(PL)spectrum of superlattice materials are studied based on the Fourier transform infrared spectrometer test system.It is verified that the response band meets the design requirements,and there is recognizable PL signal at room temperature,the overlapping degree of electron hole wave functions in the superlattice is large,and the quantum efficiency is high.The liquid nitrogen refrigeration75-300 K variable temperature photoluminescence experiment further verifies the high crystal quality and luminescence characteristics.What is worth paying attention to is the slight abnormal spectral phenomenon,indicating that there may be local states.3.Research on carrier localization and minority carrier lifetime characteristics of InAs/InGaAsSb T2 SL.We use the liquid helium refrigeration test system to carry out low temperature and variable power and temperature PL experiments,and confirm the existence of band bending caused by localization.The localized carrier collective fluorescence(LSE)model was used for the first time to analyze the effect of localization on the luminescence performance.The minority carrier lifetime extracted at 90 K is about 800 ns measured by optical modulation response(OMR).The prolongation of minority carrier lifetime is expected to realize infrared detection at high operating temperatures.