Study On The Structural Calculation And Oxidation Process Of 976nm High Power VCSEL

Compared with edge-emitting semiconductor lasers,vertical-cavity surface-emitting lasers(VCSELs)have advantages in terms of optical field mode,modulation rate,output power,and mass fabrications.Therefore,the development of such devices has always been one of the important branches of semiconductor photoelectric devices.As the VCSEL devices have played an increasingly important role in areas such as consumer electronics,3D sensing,virtual reality,laser lighting,laser weapons,laser guidance and other fields in recent years,more and more scientific and technical researches have been carried on the VCSEL device designing and fabricating at home and abroad.This research mainly focuses on 976 nm high-power VCSELs applied to infrared illumination,including the structural design and calculation of 976 nm high-power VCSELs,the analysis of material properties for DBR structures,the study on wet oxidation processes and device fabricating process.The following conclusions can be drawn:Based on the transmission matrix theory,the reflective properties of the DBR structure were calculated and optimized;the MQW structure were theoretically calculated and designed by the strained quantum well theory;the overall epitaxial material structures of the 976 nm high-power VCSEL were finally designed.According to the theoretical calculation results of DBR structure,different doping Alo.9Ga0.1As/GaAs DBR structures were designed and grown.The effects of different doping types and concentrations on the material properties and photo-luminescence properties of DBR structures were studied through XRD rocking curves,SEM images,ECV testing,and low temperature photo-luminescence spectra.The results showed that the grown DBR epitaxial layer had good crystal quality and interface properties,the doping concentration and distribution were consistent with the design requirements.Period thickness would be decreased by the CCl4 doping process for AlGaAs and GaAs layers,and AlGaAs layer could get a higher doping concentration than that of the GaAs layer.Additionally,there were four recombination mechanism in the varied doping Alo.9Ga0.1As/GaAs DBR structure,and the recombination between the first conduction band energy levels and the acceptor levels in the valence band dominated the photo-luminescence in the lower temperature,the proportion of the recombination gradually decreased with the increasing of temperature,while the recombination between the conduction band and valence band played a dominant role at room temperature.The wet oxidation processes were studied for high Al Al0.98Ga0.02As and Alo.9Ga0.1As in the epitaxial material structure at different oxidation times.The results showed that a linear tendency was found between oxidation depth of Al0.98Ga0.02As layer and oxidation time in a relatively short oxidation time,while it transformed into parabolic tendency and gradually became saturated with the increasing of oxidation time.When the curve reached saturation,it would cause oxidation of Alo.9Ga0.1As layer with the increasing of oxidation time.Moreover,the oxidation rate of Al0.98Ga0.02As was higher than that of Alo.9Ga0.1As layer by one order of magnitude,and it would increase the wet oxidation rate of the Alo.9Ga0.1As layer as the layer thickness increasing.By Analyzing and fitting experimental data obtained for the oxidation of the Al0.98Ga0.02As layer,a mathematical model was established based on the one-dimensional Deal-Grove oxidation model,and parameters were modified to interpret the oxidation process of the Al0.98Ga0.02As layer.The oxidation of the Al0.98Ga0.02As layer was theoretically calculated.and the relationship between the oxidation depth of the Al0.98Ga0.02As layer and the oxidation time was obtained,and the mechanism was analyzed for the AlGaAs wet oxidation,we pointed out the process conditions for improving the accuracy of the oxidation process.Finally,the designed 976 nm high-power VCSEL material structure was grown by MOCVD,and its material structure were analyzed for crystal quality and doping concentration distribution.The results showed that the structure of the grown material was in accordance with the design values,and the reflective spectral properties also met the requirements of device fabrication.The fabrication processes were initially designed for the 976 nm high-power VCSEL devices,and part of the fabrication processes were performed.