Preparation Of N-AlGaInP Ohmic Contact And Optimization Design Of AlGaInP Thin Film Light-emitting Diode

As a new generation of green light source,light-emitting diode(LED)has the advantages of high efficiency,energy saving,environmental protection and long life.LED plays an important role in the development of energy conservation,emission reduction and low carbon.The quaternary AlGalnP material is widely used in red LED.By adjusting the composition of AlGalnP material,it can match with GaAs substrate.The prepared LED wavelength can cover the red,orange,yellow and yellow-green bands(550-660 nm).By optimizing the epitaxial structure,high quality AlGalnP materials can be grown and the internal quantum efficiency was over 90%.Through the preparation of thin film LED,its output efficiency has also been greatly improved.However,AlGalnP thin film led still needs further research in improving light extraction efficiency and reducing cost.In addition,660 nm wavelength LED used for plant growth lighting needs to use high in component strain GaInP material.In order to obtain high internal quantum efficiency,quantum wells need to be well optimized.Aiming at the above problems of high light efficiency AlGaInP thin film LED,a series of electrode preparation and device simulation are carried out in this paper.The main research contents and achievements are as follows:1.The effects of surface treatment,metal evaporation sequence,thickness of metal layers and annealing conditions on ohmic contact properties of n-AlGaInP were studied.The electrode system based on Au/Ge/Ni alloy system is the key to prepare n-AlGaInP ohmic contact.It can be seen from the SIMS test results that during the annealing process,the out-diffusion of Ga and in leaves the group III vacancy in the lattice,and the in-diffusion of Ge occupies the Ga vacancy and in vacancy in the alloy layer and becomes the donor providing electron.Therefore,the mutual diffusion is attributed to the main reason of ohmic contact formed by n-AlGaInP in this paper.When the doping concentration of n-AlGaInP is 3 ×1018 cm-3,its specific contact resistance reached 1.4×10-4? cm2 when annealed at 445? for 600 seconds.2.According to the calculation principle of ODR reflectivity,the influences of different media layer materials,media layer thickness and metal reflector materials on ODR reflectivity are theoretically simulated.The optimal structure of ODR mirror for AlGaInP thin-film LED chip is GaP/SiO2 100 nm/Ag?In addition,this paper discussed the influence of different p-GaP thickness on the photoelectric performance of AlGaInP LED devices.The results show that when the thickness of p-GaP is 1.5 ?m,the current spreading and the ODR reflectivity were imporved.So the photoelectric performance is better.3.The device simulation of AlGaInP LED is carried out by APS YS semiconductor simulation software.The internal quantum efficiency is taken as the index,and the two factors of well width and Ga component of quantum well structure are cross optimized.The simulation results show that the red LED with 660 nm wavelength has higher internal quantum efficiency and smaller lattice mismatch when the equivalent quantum well material is Ga0.422In0.578P and the thickness is 6 nm.The optimized MQWs structure is better for the actual product index.