Structural Design Of 265nm Deep Ultraviolet Laser

Deep-ultraviolet lasers are widely used in high-density optical data storage,medical sterilization,laser display,and satellite communications.In recent years,scholars and research institutions at home and abroad have had a strong Interest in exploring lasers in the deep ultraviolet range.At present,the deep ultraviolet laser is selected from the ternary compound AlGaN,which can cover the deep ultraviolet band(220 nm to 280 nm)by controlling the Al composition in the ternary compound AlGaN composed of AlN and GaN.The goal of this study is to achieve lasing using device in the 265 nm band and to optimize the device based on this structure to obtain better laser output performance.The main focus of this thesis is as follows:The development status of laser nationally and internationally is introduced,and the significance of the research direction is indicated.The working mechanism of the laser device and the working material-AlGaN material properties are discussed in detail.In addition,various physical models are used for electrical and optical simulation of the laser device are also introduced.The environment of this simulation research is based on the Lastip software of CrossLight,so the operation flow of the software is also briefly explained.The laser designed in this paper is a power laser with a target laser wavelength of 265 nm.Firstly,the most basic double heterostructure is designed.The active region is a quantum well structure of Al0.58GaN/Al0.68GaN.However,the photon energy generated by this structure is dispersed along the active region of the device,and the ridge structure is etched on the P-type cladding of the structure in order to concentrate the output energy.Based on the ridge quantum well structure,the quantum well structure in the active region is first optimized.Through simulation studies,the number of equivalent sub-wells is 2,which has the largest stimulated recombination rate for this device structure.And because of the high mobility of electrons,electrons will pass over the active region.In this case,adding 10 nm thick Al0.88GaN layer to the device structure can effectively suppress electron leakage.Since the etched ridge structure is equivalent to the reduction of the hole region and the mobility of the hole is originally low,the composition and thickness are optimized for the P-type waveguide layer,respectively,and the device structure is determined.The threshold current of the device was 33 mA,the slope efficiency was 1.417 W/A,and the electro-optical conversion efficiency was 32.9%,However,due to the strong spontaneous and piezoelectric polarization of AlGaN materials,this characteristic will affect the output performance of the device.In order to get closer to the actual performance of the device,this paper also discusses the polarization performance of the laser output.After considering the polarization effect,the threshold current of the laser is increased by 7 mA,and the electro-optic conversion efficiency is reduced by 2.3%,which lowers the output performance of the device,Using Boron Nitride as a new laser material,the active region is designed as a new structure of B0.39GaN/B0.45GaN,and the threshold current of the laser is 27mA,The slope efficiency is 1.219W/A,and the electro-optic conversion efficiency is 26%,although the optical performance of this structure It has decreased,but its electrical performance has been improved,and its threshold current has been reduced by 6 mA.Finally,the electrical properties of the deep ultraviolet power laser are improved.Hence,it will provide the basis for future research on new BGaN lasers.