Light-emitting diode (LED) with reflector structure

Abstract

The invention relates to a light-emitting diode with a reflector structure. The light-emitting diode with the reflector structure sequentially comprises a metal layer, a distributed Bragg reflector (DBR) layer, a substrate, a buffer layer, an undoped GaN layer, an n-type GaN layer, an n electrode formed on the n-type GaN layer, an active layer, a p-type GaN layer, a transparent conductive layer and a p electrode formed on the transparent conductive layer from bottom to top, and is characterized in that a transition layer for improving the adhesion of the DBR layer and the metal layer is inserted between the metal layer and the DBR layer; and the metal layer, the transition layer and the DBR layer form the reflector structure of the light-emitting diode. According to the light-emitting diode, an Ag metal reflection layer is adopted, and an Au barrier is not required, so that the using amount of Au is reduced; in addition, the reflectivity of Ag is higher than that of Al, so that the reflectivity is favorably improved; and moreover, the transition layer is inserted, so that the problems of low adhesion and high separation rate of Ag and the DBR layer are solved.

Description

technical field [0001] The invention relates to the technical field of optoelectronic devices, in particular to a light emitting diode with a mirror structure. Background technique [0002] The luminous efficiency of LED is limited by the external quantum efficiency, and the external quantum efficiency is determined by the internal quantum efficiency and light extraction efficiency. The internal quantum efficiency depends on lattice defects, doping efficiency and ohmic contact performance, etc. With the continuous development of the MOCVD process, the internal quantum efficiency has reached 80% to 90%, while the light extraction efficiency is currently only about 40%, and there is a lot of room for improvement. An important reason for the low light extraction efficiency is that the back of the chip (sapphire) is in direct contact with the packaging glue (insulating glue or silver glue), and the light emitted from the active layer is refracted from the back and directly abso...

AI Technical Summary

Problems solved by technology

[0003] The current mainstream method is to make a DBR layer and a metal layer on the back of the substrate. The metal layer materials are mainly selected from Al, Cr, Pt, and Au. Among them, Al is used as the main reflective metal layer, and Cr, Pt, and Au are used to protect Al from oxidation. Among all metal materials, the reflectivity of Al is 90%, while the reflectivity of Ag is greater than 98%. Therefore, it is a general trend to replace Al as the back metal layer by Ag, but on the other hand, due to the distribution of Ag and DBR (distributed Bragg reflection, There is a big problem with the adhesion of the layer oxide, which leads to the shedding of Ag directly on the DBR layer

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