Study On The Epitaxial Growth Of 940 Nm Vertical Cavity Surface Emitting Laser

With the applications of 3D sensing and face recognition technology in mobile phones,the 940 nm vertical cavity surface emitting laser（VCSEL）,as the core component of the two technologies,is bound to have greater and broader development prospects in the future optoelectronic technology fields.And VCSEL has the advantages of low threshold current,easy high-frequency modulation and two-dimensional integration,dynamic single-mode operation,ect.However,there are problems such as imperfect epitaxial growth technology,insufficient experience,low yield and low reliability in device research.Therefore,this dissertation had carried out the epitaxial growth research work from active region,distributed Bragg reflector（DBR）to VCSEL.Using metal organic compound vapor deposition technology（MOCVD）,by optimizing growth conditions such as growth thickness,temperature,doping concentration,etc.,we conducted research on the epitaxial growth technology of 940nm VCSEL.For the active region,a high-barrier InGaAs/AlGaAs multiple quantum wells（MQWs）structure is designed.Under the premise of its high differential gain,it focuses on solving the problem of Induim atoms segregation in the well layer during the epitaxial growth process.By designing an ultra-thin Ga As material insertion layer in the MQWs structure and optimizing the thickness of the insertion layer,the best performance MQWs structure is obtained.Through theoretical research and testing analysis of the high crystalline quality MQWs structure,it shows that the AlGaAs barrier can increase the probability of radiation recombination in the MQWs structure,and the Ga As inserttion layer can reduce the surface roughness and the segregation of Induim atoms.For DBR,we explored p-type DBR structure design,epitaxial growth,testing analysis.Using PICS3D software,22 pairs of p-type Al_0.9Ga_0.1As/Ga As DBR structures were designed and simulated,with a maximum reflectivity of 99.58%and a reflection bandwidth of 103 nm.At the same time,combined with the composition gradient and step doping at the heterojunction interface,a DBR structure with high reflectivity,high thermal conductivity,and low series resistance was designed,and the structure was epitaxially grown using MOCVD,and the reflectance was measured with a spectrophotometer.The Hall effect device was tested for resistivity and doping concentration.By optimizing the structure and growth conditions,a DBR epitaxial structure with high reflectivity and low loss was obtained.Aiming at VCSEL,combining the temperature shift of the quantum well gain wavelength in the active region,and the influence of the temperature change of the material refractive index in the DBR structure on the Bragg wavelength,the 940 nm VCSEL was designed by using PICS3D software by adjusting the material composition and thickness of the spacer layer,and simulated the VCSEL gain spectrum,threshold current,cavity mode position and other parameters.Using MOCVD technology to epitaxially grow a 940 nm VCSEL,and it was tested the cavity mode position by a white light spectrometer,and the uniformity of the epitaxial wafer was measured by mapping testing.By analyzing the test results,optimizing the structure and growth conditions,the epitaxial growth of a 940 nm VCSEL chip was completed.With the widespread application of VCSEL in 3D sensing,lidar and other fields,the epitaxial growth of high-quality,high-reliability VCSEL chips has important practical significance for the fabrication of high-power,high wall-plug efficiency,high modulation bandwidth and high-performance devices.