The Effect Of Arsenic Molecular Beam Species On The Properties Of InGaAs/AlGaAs Quantum Well Infrared Photodetector

GaAs-based QWIP has a wide range of application prospects in the field of infrared detection because of its superior material uniformity,flexible band clipping,and mature growth preparation process.However,due to the band structure limitations of traditional GaAs/AlGaAs materials,the response wavelengths are often limited to long-wavelength and very-long-wave regions.Using InGaAs/AlGaAs material systems,it is easy to achieve imaging and detection of medium-wavelength infrared(3-5?m)with reasonable energy band design.However,the InGaAs/AlGaAs material system is difficult to fabricate because of the large difference in growth window between InGaAs and AlGaAs and the lattice mismatch between InGaAs and AlGaAs.In addition,the effect of the arsenic molecular state on the basic properties of InGaAs/AlGaAs QWIP has not been systematically studied.As a very easy means of adjustment,changes in the arsenic source cracking zone temperature can improve the performance of GaAs-based QWIP materials,such as reducing the dark current of the device,improving the specific detectivity,etc,which will have a very important.effect on the quantum well infrared detector field.This article mainly starts from these two aspects.By growing AlGaAs quantum well samples at three different temperatures,the growth temperature of the InGaAs quantum well layer is fixed at 460?,the growth temperature of the Al GaAs barrier layer is 460?,500? and 540?,respectively,highresolution XRD and AFM characterizations were performed and the following conclusions were obtained,with the increase of the Al GaAs layer growth temperature,the full width half maximum(FWHM)of the(004)surface-1 level satellite peaks of the three samples gradually decreased,but the surface roughness first decreased and then increased.For this reason,we explained that when the growth temperature of the AlGaAs layer is 460?,the crystal quality of the AlGaAs layer is not very good,so the FWHM is relatively large.When the growth temperature of the AlGaAs layer is 500?.,the crystal quality of the AlGaAs layer becomes better,and the InGaAs layer is in an elastic relaxation process,so the FWHM becomes smaller and the roughness decreases.When the growth temperature of the Al GaAs layer is 540?,although the crystal quality of the AlGa As layer can be improved,a large number of defects are generated in the InGa As layer,which deteriorates the quality of the entire interface and maximizes the roughness.Based on the initially optimized InGaAs/Al GaAs quantum well materials,we have grown InGaAs/AlGaAs QWIP samples with different arsenic molecular states by changing the arsenic source cracking zone temperature(600°C,800°C,900°C),through subsequent characterization,it was found that single-layer AlGaAs material grown under As2 mode has stronger fluorescence intensity and less deep level defect density,the InGaAs/AlGaAs QWIP grown under As2 conditions has a lower dark current level,a better blackbody response,a higher specific detectivity and a better device uniformity.This is because the more complex adsorption growth mechanism under As4 conditions leads to a greater density of material defects,resulting in a weaker luminescence intensity and a larger dark current density.The InGaAs/AlGaAs QWIP produced by us has obtained a very low dark current density,and a high specific detectivity is obtained at a peak wavelength of 3-4 ?m.