Simulation Study Of 267nm AlGaN And BGaN-based Deep Ultraviolet Lasers

Deep ultraviolet semiconductor lasers have great application potential in chemical analysis,medical diagnostic equipment,biological reagent detection system,high density data storage,water purification and material processing.They can also effectively replace toxic and inefficient gas lasers and mercury lamps.In this paper,a deep ultraviolet laser with an exciting wavelength of 267 nm and excellent performance is designed.The output performance of the laser is improved by optimizing the structure of the laser.Firstly,the background,working principle and physical model of deep ultraviolet laser are introduced,and then the working process and simulation environment of Lastip software of Crosslight are summarized.Then we begin to study the current problems of laser,including low hole injection efficiency,serious electron leakage and serious polarization effect in active region.In order to solve these problems,this paper mainly carried out the following four aspects.1.To improve the hole injection efficiency and reduce the threshold current density of the laser,this paper analyzes the reported solutions,and concludes that the p-cladding layer of the laser needs to be optimized.Then,the p-cladding structure with gradually decreasing Al component is proposed.The light field distribution,electrical properties and carrier concentration of the structure were calculated,and compared with the traditional structure and the p-cladding layer structure with gradually increasing Al component.It is found that the p-cladding layer laser with gradually decreasing Al component can effectively improve the performance of the laser,especially in reducing the current density and increasing the hole concentration.2.On the basis of optimizing the p-cladding layer,in order to reduce the electron leakage,an inverse-trapezoidal electron blocking layer laser is proposed according to the working principle of the deep ultraviolet laser.The electron blocking layer of this structure is designed to match the lattices of the upper and lower layers.Through the analysis and comparison with many electron blocking layer structures reported at present,it can be seen that the inverse-trapezoidal electron blocking layer laser proposed in this paper has the best effect on reducing electron leakage and further improves the performance of other aspects of the laser.3.Due to the serious polarization effect of the laser,the emerging BGaN is used as the material of the active region of the laser in this paper.We have calculated and simulated Al GaN quantum well laser and BGaN quantum well laser.The optical characteristics,electrical characteristics and radiation recombination rate of the two lasers are studied.The research results indicate that BGaN quantum well laser has more advantages than Al GaN quantum well laser in these three aspects,especially in reducing threshold current and increasing output power.4.To improve the radiation recombination rate of the laser,the physical mechanism of the quantum well structure and the influence of several reported quantum well structures on the laser performance are studied and analyzed.Then the BGaN convex quantum well laser is proposed and compared with the traditional structure and BGaN convex quantum barrier structure.The results indicate that the BGaN convex quantum well structure can effectively improve the radiation recombination rate of the laser.