Research On The Structures Of 300nm GaN-based Semiconductor Laser Diodes

Following the Si and GaAs-based materials,the GaN-based materials are the third generation of semiconductor materials with superior characteristics,such as large bandgap width,high electron mobility and so on.The GaN-related alloys are direct bandgap semiconductors with high luminous efficiency.The band gap is in the range of about 0.7 to 6.2 eV,corresponding to a wide wavelength range from green,blue,violet to ultraviolet.Therefore,it is suitable for optical devices.The structures of semiconductor laser device is relatively compact and can provide lasing in a small volume.Furthermore,semiconductor lasers have the characteristics of high luminous efficiency,fast response,long lifetime,etc leading to various applications in information and communication,laser display,underwater detection,biological sciences and military fields such as laser radar.In this paper,the GaN-based semiconductor lasers with wavelength of 300 nm are in the range of deep ultraviolet,and they can be widely used in the fields of biological detection,medical sterilization,missile warning and satellite encryption.This paper firstly introduces the research background,applications and basic principle of semiconductor lasers.Then,numerical calculation modelwas established.The device with 300 nm wavelength is basically simulated.The simple structure is obtained by using double heterojunction structure(Structure A).As a result,the laser with threshold current of 1.092 A,threshold voltage of 6.052 V and slope efficiency of 0.042 W / A are achieved.However,the distribution of optical lateral modes is relatively large,thus structure A is improved by adding the ridge structure(structure B).The simulation results indicates that the distribution of optical lateral modes is denser than that of the structure A.Compared to structure A,the threshold voltages of structure B increased by 16%.Then,the quantum well structure was introduced to enhance the overall performance of the laser(structure C).As a result,the laser threshold current of structure C is reduced by 39.5%,the slope efficiency is improved by 116.7%,compared to the structure B.The overall performance of structure C was greatly improved.Next,the electron blocking layer is introduced to improve the performance of the laser(structure D),the slope efficiency of structure D is increased by 19.8%,compared to the structure C.After that,accompanied with the use of component gradient design to further enhance the performance of the laser(structure E),the laser threshold current is reduced by 12.3%,the slope efficiency is improved by 15.6%,compared to the structure D.Totally,compared to structure A,,the laser threshold current is reduced by 44.6% and the slope efficiency is improved by 200% for structure E.The above results prove that the structure optimization are effective for the performance improvements of 300 nm GaN-based laser diodes.