Growth And Characterization Of Short-wave Infrared InGaAs Materials Based On Heteroepitaxy

Extended-wavelength InGaAs short-wave infrared detectors are receiving continued attention due to their potential applications in aerospace remote sensing,lowlight night vision,agriculture,gas detection,and medical diagnostics,and are moving toward higher performance,higher integration,larger scale,and lower power consumption.However,there is a mismatch between the extended-wavelength InGaAs and the InP or Si substrate,and the high mismatch dislocation density is a key factor restricting the performance improvement of the device.This paper is aimed at the preparation of extended-wavelength InGaAs short-wave infrared detectors,mainly around the heterogeneity and characterization of extended-wavelength InGaAs materials on different substrates.The main research contents and achievements are as follows:1.High quality In0.76Ga0.24As heteroepitaxy with a mismatch of 1.6%with the InP substrate was realized.After obtaining the composition calibration curve of InAsyP1-y,two kinds of buffer layer structures,conventional compositionally step-graded(CSG)and compositionally undulating step-graded(CUSG),were grown and their effect on the surface morphology,relaxation,microstructure,and optical property were studied.Under the alternating action of tensile/compressive strain,the dislocations in the CUSG structure were accelerated to slip and annihilate in the InAsyP1-y buffer layers,which was conducive to more sufficient stress relaxation and reduction of the surface roughness,combined with crystal quality and optical property improment.The surface roughness of the In0.76Ga0.24As grown on the CUSG InAsyP1-y buffer layer with a total thickness of 2.09 μm is only 1.38 nm which is the lowest value in reported InGaAs material with similar wavelength,and the PL intensity at room temperature was increased by 4 times.The temperature-dependent PL results showed that there are two non-radiative recombination mechanisms related to interfaces and dislocations in the material,and the reduction of non-radiative recombination centers related to dislocations is the main reason for improving luminescence at room temperature.2.InP-based InGaAs short-wave infrared detector was prepared.The 50%cutoff wavelength of the device was 1945 nm.The dark current density was 0.83 nA/cm2 under the reverse bias of 10 mV,and the corresponding deep level trap density was about 1012 cm-3.And the capacitance was 144 pF at 1 MHz and 0 V bias.3.The optimized conditions for homoepitaxial GaP on GaP/Si(100)template were obtained.The effects of growth temperature,Ⅴ/Ⅲ ratio and desorption temperature on the surface morphology of GaP were studied.Under suitable desorption conditions,2D step flow surface could be obtained at～628℃ with the Ⅴ/Ⅲ ratio of 10～20.Excessive desorption would make GaP with poor crystalline quality in the GaP/Si(100)template completely decompose or form GaP clusters,which became defect nucleation centers for subsequent heteroepitaxy and showed dislocation aggregation effects.At the same time,it was found that the superlattice dislocation filter layers(DFLs)can repair the blurred interfaces.With the increase of the number of DFLs,the dislocation filtering effect is more obvious,but it is less effective to the stacking fault.Stacking faults generated in DFLs interact and extend to the surface to form pair defects.4.The effect of the low temperature layer on the properties of the In0.64Ga0.36As material on the GaP/Si(100)template was studied.Thermal stress induced by in-situ annealing accelerates the slip of dislocations in the low temperature layer,which can effectively improve the quality of the In0.64Ga0.36As epitaxial layer;and the mismatch stress is mainly relaxed by generating high-density edge dislocations in the low temperature layer.The InAs/InP digital alloy low temperature layer combined with higher annealing temperature can further reduce the surface roughness and the dislocation density,making the room temperature luminescence intensity of the material increased by 2 times.The research on the optical properties of In0.64Ga0.36As shows that there are two kinds of non-radiative recombination centers in In0.64Ga0.36As on GaP/Si(100),among which the deep level recombination centers are mainly derived from VⅢ vacancies in the material.5.The effects of different initial atoms on the surface and interface of GaP/Si(100)were studied by theoretical calculation and experiments.The results showed that when the initial atom is P,the Si atoms on the substrate surface were replaced by P atoms to form a Si-P heterodimer,which causes the surface roughening,and there is a miscibility zone at the interface,which is mainly due to electron exchange of Si-P bond with residual electrons and Si-Ga bond with missing electrons.The GaP/Si(100)interface with Ga as the initial atom was clear.The conclusions derived from experimental and theoretical calculation were consistent.The GaP surface roughness was reduced to 0.57 nm by optimizing the Ga sputter-time.