Investigation On Molecular Beam Epitaxy Of Gaas-based Laser Material On Silicon And Dislocation Guiding Structure

In recent years,silicon-based photonic integrated chips have rapidly expanded their application scenarios due to their advantages of high integration density,high immunity to interference,low power consumption.Starting from being limited to data centers,they have gradually extended to fields such as autonomous driving,consumer electronics,and artificial intelligence,demonstrating tremendous application potential.However,their integration schemes also face greater challenges.Among the existing silicon-based photonic integration schemes,the single-chip integration scheme has become the recognized mainstream development direction in the industry due to its advantages of low cost and high integration density in large-scale production.Detectors,modulators,and other devices have well-established silicon-based single-chip integration schemes.However,silicon,an indirect bandgap material,is difficult to serve as the gain medium for lasers,which poses a significant obstacle to developing singlechip integration.Direct epitaxial Ⅲ-Ⅴ semiconductor lasers integrated on silicon are considered promising solutions to address the silicon-based light source problem,with silicon-based quantum dot lasers and quantum well lasers showing potential applications.However,the differences in physical properties between silicon and III-V materials lead to various defects,which act as non-radiative recombination centers and significantly limit the performance of silicon-based lasers.Against this background,this paper aims to improve the performance of direct epitaxial silicon-based lasers by focusing on silicon-based heteroepitaxy technology and laser structure design as the optimization entry points.The research work is centered around silicon-based quantum well lasers and silicon-based quantum dot lasers.The main research content and achievements are as follows:1、A structure of misfit dislocation guiding layer in silicon-based quantum well lasers was designed to reduce the misfit dislocation in the active region,achieving a significant reduction in the threshold current and an increase in the reliability of the laser.Firstly,the silicon-based GaAs heteroepitaxy technology was optimized,and the structure of the misfit dislocation guiding layer was designed.Subsequently,two groups of silicon-based quantum well laser samples were fabricated.Sample A did not have a misfit dislocation guiding layer,while sample B used an InAlAs misfit dislocation guiding structure.The samples were tested and analyzed.In the pulsed mode at room temperature,the threshold current density of sample A is 3.73 kA/cm2 and that of sample B is 1.39 kA/cm2,which is only 37%of that of sample A.In addition,in the continuous mode at room temperature,sample A is not lase,and sample B has a threshold current density of 2.7 kA/cm2 and a single-facet output power of over 45.3 mW with a slope efficiency of 0.143 W/A.2、A material growth scheme combining metal-organic chemical vapor deposition(MOCVD)and molecular beam epitaxy(MBE)for fabricating silicon-based quantum dot lasers was proposed.This scheme was utilized to fabricate silicon-based quantum dot lasers with high slope efficiency.Firstly,an on-axis Si(001)substrate is subjected to hydrogen annealing in an MOCVD system,promoting the generation of surface double atomic steps and enabling the growth of a GaAs/Si substrate without antiphase domains.Subsequently,the unique advantages of MBE technology are utilized to grow structures such as superlattice layers,cladding layer,and quantum dot active regions on the aforementioned substrate.A density of 4.6×1010 cm-2 and a photoluminescence spectrum with a full width at half maximum(FWHM)of 30.5 meV are achieved.Finally,a GaInP upper cladding layer is grown in the MOCVD system to form an asymmetric waveguide structure.The fabricated silicon-based quantum dot laser achieves continuous-wave lasing at room temperature,with a threshold current density of 203.5 A/m2,a single-facet output power exceeding 63.9 mW,a slope efficiency of 0.158 W/A,and a lasing wavelength in the O-band.The estimated lifetime at 85℃ is approximately 1149 hours,suggesting a lifetime exceeding 21000 hours at room temperature.