Research On The Principle And Performance Improvement Of GaN-based LED Chips

Light-emitting diodes(LED)have been widely used in green intelligent lighting,display technology,visible light communication,automotive lighting and other fields because of its high light efficiency,long life,fast response,small size and good seismic performance.In actual production,in order to prepare LED chips with better performance and stability,many key technologies need to be explored continuously.This thesis focuses on three key technologies to improve the performance of GaN LED:ITO transparent conductive film technology,distributed Bragg reflection technology,chip cutting technology.The work done is mainly in the following aspects:1.By optimizing the growth technology of ITO film,the compactness,conductivity and transmittance of ITO film are optimized,and the brightness of LED chip is improved by 3.02%.In this thesis,ITO films were grown by magnetron sputtering instead of electron beam plating.With rapid annealing technology,the compactness,conductivity and light transmittance of ITO films were optimized.The thickness of ITO film is 50 nm and the annealing temperature is 550 ?.2.By optimizing the structure of distributed Bragg reflection(DBR),the compactness and adhesion of DBR films were effectively improved.After splitting and separation,the breakdown ratio of DBR films decreased from 53%to 5%.After the introduction of DBR film into production,due to the poor compactness and adhesion,a large number of cracks and membrane layer collapse occurred after separation,which could not achieve the expected effect of brightness improvement.By adjusting the energy intensity of charged particles in the ion source,i.e.adjusting the ion source voltage,the compactness and adhesion of DBR film can be effectively improved when the ion source voltage is greater than 600V.3.By using picosecond laser cutting instead of ultraviolet laser cutting,the brightness of LED products increased by 3.89%.By increasing the number of laser focus in the vertical direction,the chip oblique cracking caused by the lattice structure of the substrate can be improved.When the number of focus increases to 3,the sapphire oblique cracking angle after laser cutting can be improved from 84.4 to 89.6 degrees,which effectively improves the oblique cracking condition of GaN-based LED.Through the above process control optimization and experiments,and the results of optimization into production,the brightness of LED can be improved from 166.48 mW to 177.52 mW,the proportion of increase is 6.63%,the proportion of DBR film collapse is reduced by 48%,and there is no oblique crack after laser cutting,which improves the performance of LED.