Structure Design And Fabrication Of High-strain InGaAs Quantum Well Laser

Quantum well semiconductor laser has been a promising laser,which has the advantages of good quantum effect,good temperature characteristics,low threshold current density,high output power and long life.It has been widely used in industry,communication,national defense,military,medical care and other fields,and has become the focus of research in the field of optoelectronic materials and devices at home and abroad.In order to obtain the epitaxial materials of long wavelength semiconductor lasers,it was necessary to obtain high quality and high strain In Ga As/GaAs quantum well materials.However,it is very difficult to obtain high quality epitaxial materials due to the accumulation of material strain.Based on the theoretical analysis of the waveguide structure of the semiconductor laser,this paper further discusses the relationship between the structural parameters and the output performance of the high-power semiconductor laser.From the aspects of the structural design,epitaxial growth and device characteristics of the semiconductor laser,the ways to improve the output characteristics of the high strain semiconductor laser are discussed.The main research contents and achievements are as follows:(1)The influence of high-strain InGaAs quantum well structure on the performance of the device was studied by numerical simulation.The influence of the central waveguide layer,the extended waveguide layer and the inner limiting layer on the performance of the device was analyzed in detail.The effects of mode expansion layer on threshold current,limiting factor and vertical divergence angle of laser were analyzed theoretically.The method of reducing the waveguide optical loss by using wide waveguide and asymmetric waveguide structure and the way of improving the barrier voltage drop by using graded heterojunction interface are proposed.Through the design of barrier structure and characterization of carrier confinement,the barrier structure,cavity length and mesa width of quantum well were optimized.The results show that the epitaxial structure of semiconductor laser with mode extension layer can widen the near-field light field,reduce the optical limiting factor,and improve the COD threshold of semiconductor laser.A 1.5 ?m high and 50 ?m wide asymmetrical and wide waveguide strained quantum well laser is designed.The simulation results show that when the threshold current of the laser is 118.94 mA,the far-field vertical divergence angle is 22°,and when the threshold current is 204.9 mA,the far-field vertical divergence is 17°.According to the simulation results and theoretical calculation,the overall epitaxial structure of quantum well laser is determined.(2)The key factors affecting the luminescence properties of quantum wells,including substrate offcut angle,growth temperature,growth rate and V / III ratio,and their mechanism of action,were studied experimentally.A variety of quantum well lasers have been fabricated by changing the preparation conditions and parameters.By means of AFM appearance image detection,X-ray diffraction detection and PL detection,the influence of different factors on its optical performance was compared.The results show that the substrate deflection angle was the key factor affecting the quantum well.A small substrate deflection angle will lead to a significant increase in the photoluminescence intensity and a significant decrease in the half peak width,thus improving the optical properties of the material.On the other hand,by reducing the growth temperature,the intensity of in increases significantly,and the half peak width decreases,thus changing the composition of in and the thickness of the well layer,resulting in a red shift of wavelength and improving the optical performance of the quantum well.In addition,growth rate and V / III ratio are also important factors affecting optical properties.By increasing growth rate,the quality of quantum wells can be effectively improved,and by increasing V / III ratio,the optical properties of InGaAs/GaAs quantum wells can be improved.Finally,the In GaAs quantum well laser with a wavelength of 1290 nm is obtained.(3)The passivation and cleavage technology of quantum well lasers was studied and analyzed in detail.The key factors affecting the vacuum cleavage and passivation technology of semiconductor lasers were analyzed by the XPS test energy spectrum technology.The semiconductor laser cavity mask technology was used to solve the problem of semiconductor laser end face damage degradation,and realize the longer life and higher power of semiconductor lasers.The InGaAs quantum well laser designed in this paper has been fabricated.The threshold current is about 482 mA,and the slope efficiency is 0.45 W/A.when the continuous current is 1.5 A,the peak wavelength of the laser is 1295 nm,which is in accordance with the designed quantum well laser and achieves the expected effect.