Study On Growth And Strain Compensation Of InGaAs Quantum Well Materials

Semiconductor laser is an optoelectronic device with miniaturization and high efficiency,which has been continuously improved in the aspects of increasing emitting power,reducing threshold current density,improving device stability,extending the emission wavelength range,etc,and has broad development prospects.Among them,the semiconductor laser with strained InGaAs/GaAs quantum well structure as the active region is the most widely applied,and this structure can achieve higher gain.However,there are still some problems to be solved in the growth of strained quantum well materials.For example,clusters caused by atom segregation will lead to localized states in the material under high In components.Aiming at the above problems,the growth of high-quality InGaAs/GaAs（P）quantum wells is studied in this paper.The details are as follows:（1）In response to the problem of defects in the GaAs substrate,research has been carried out to optimise the growth of high quality GaAs buffer layers.The optimum growth conditions for the preparation of buffer layers on different substrates were obtained by optimising the growth parameters such as substrate deflection angle and reaction chamber pressure.The 200 nm buffer layer on 0°substrate is most suitable when the reaction chamber pressure is 100 mbar and the growth temperature is 650℃.The buffer layer with different angles（2°,4°,10°）substrate has the smallest half-peak width at 500 nm and gives the best results.This has been used as a basis for quantum well growth studies,and theoretical simulations and experimental studies of In_xGa_1-xAs/GaAs strained quantum wells have been carried out to grow quantum well materials with In components ranging from 0.17-0.40.The PL spectra of the samples were analysed and it was found that the half-peak width increased as the In component increased,the homogeneity of the mapping test fluctuated more and the crystal quality decreased（2）The study on In_0.29Ga_0.71As/GaAs multi-quantum wells found that there are localized states in the epitaxial materials with high In components.The temperature-and power-dependence PL test results show that the excitation of localized state plays a dominant role at low temperature.In addition,by reducing the growth temperature and rapid thermal annealing of the sample,the influence of the localized state on the growth quality of the crystal is weakened,and the optical performance of the material is improved.The test results also show that the wavelength redshifts as the growth rate increases and that the wavelength redshift becomes more pronounced as the growth rate increases more.（3）For high strain InGaAs/GaAs quantum well material,strain compensation structure with GaAsP was introduced as quantum barrier and the epitaxial growth of In_0.29Ga_0.71As/GaAs_1-xP_xwas carried out.Under the fixed In component,P component（P=0,0.16,0.25,0.34,0.39,0.49）was changed to compensate the strain.Finally,the sample with P component of 0.39 was obtained showed the best test effect and the smallest surface roughness.Through the introduction of compensation structure,the strain accumulation generated in InGaAs quantum well can be compensated to a large extent,and the maximum thickness of the well layer can be increased.In addition,the ultrathin GaAs layer is inserted between the well layer and the barrier layer.The analysis of AFM and other tests showed that the introduction of the GaAs layer can improve the growth quality of the material and reduce the surface roughness.