An epitaxial structure of a high-brightness light-emitting diode and its realization method

Abstract

An epitaxial structure of a high-brightness light emitting diode and an implementation method thereof belong to the technical field of semiconductor production. At least three pairs of coupled quantum wells grow. When each pair of coupled quantum wells grow, firstly, quantum well layers low in In content grow; and secondly, luminous quantum well layers grow, In content of each quantum well layer low in In content gradually increases along the growth direction, and a thin GaN barrier layer grows between each adjacent quantum well layer low in In content and luminous quantum well layer. A coupled quantum well structure which is low in In content and gradually increases in composition grows before a luminous quantum well by a variable temperature and variable precursor flow method, and accordingly a quantum well low in In content cannot adsorb photons emitted by the quantum well again, built-in electric field can be lowered, localization of carriers is enhanced to increase radiative recombination rate, and internal quantum efficiency of the light emitting diode is improved greatly.

Description

technical field [0001] The invention belongs to the technical field of semiconductor production, in particular to an epitaxial structure of a light emitting diode and a growth method thereof. Background technique [0002] Gallium Nitride (GaN) is the third generation direct energy gap wide bandgap semiconductor with a bandgap width of 3.39eV. GaN-based green and blue light-emitting diodes (LEDs) have the advantages of high brightness, low energy consumption, long life, and fast response, and are widely used in full-color display, signal indication, and landscape lighting. In particular, the research and development of white LEDs made of GaN-based blue LEDs mixed with phosphors is progressing rapidly. The emission wavelength of white LEDs is only in the visible light region, which avoids the strong infrared radiation of incandescent lamps and can save a lot of energy. At the same time, white LEDs are small in size, long in life, safe, efficient, and free of harmful substance...

AI Technical Summary

Problems solved by technology

Because there is usually a large lattice constant mismatch and thermal expansion coefficient difference between nitride and sapphire substrates, there are many crystal defects in the nitride epitaxial layer grown by metal organic chemical vapor deposition (MOCVD) epitaxy, such as Dislocations, etc., the crystal quality of the material is greatly affected

In particular, due to the polarization effect caused by the stress caused by the lattice mismatch between InGaN and GaN in the quantum well, there is a large polarization electric field in the quantum well, which leads to the spatial separation of electron and hole wave functions, and reduces the radiation recombination efficiency. , leading to low internal quantum efficiency of LEDs

At the same time, due to the high compressive stress in InGaN, the solid solubility of In in InGaN is low, and when the In composition is high, phase segregation and condensation are prone to occur, resulting in In precipitation; and InGaN quantum wells generally have a low growth temperature and poor material quality, which will lead to More defects in the InGaN quantum well will increase the non-radiative recombination in the quantum well and increase the light absorption in the quantum well

[0004] In order to solve the above problems, the industry and academia have proposed many methods, such as using lattice-matched AlInGaN alloys as quantum barriers (QB), QB heavy doping to improve quantum confinement Stark effect, non-polar surface growth, etc. However, these methods are theoretically feasible, and the actual epitaxial growth technology is difficult to put into actual production.

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