led

Abstract

The invention discloses multiple kinds of light emitting diodes. Each light emitting diode comprises a sapphire base plate, an N type semiconductor layer, an active layer, a P type semiconductor layer, a first electrode and a second electrode. The N type semiconductor is arranged on the sapphire base plate. The active layer is provided with an active area characterized by defect density DD >=2*107 / cm3, and the active layer is arranged between the N type semiconductor layer and the P type semiconductor layer. The wavelength lambda of light emitted by the active layer satisfies the requirement of 222nm<=lambda<=405nm, and the active layer comprises i quantum heap layers and (i-1) quantum well layers. Each quantum well layer is arranged between any two quantum heap layers, and i is a natural number larger than or equal to 2. In the active layer of one light emitting diode, N type impurities are doped in at least k layers of the quantum heap layers, and k is a natural number larger or equal to 1. When i is an even number, k>=i / 2; when i is an odd number, k>=(i-1) / 2. The first electrode and the second electrode are respectively arranged on the N type semiconductor layer and the P type semiconductor layer.

Description

technical field [0001] The invention relates to a light emitting diode, in particular to a light emitting diode (light emitting diode, LED for short) which can improve luminous efficiency. Background technique [0002] A light-emitting diode is a semiconductor element, mainly composed of III-V group element compound semiconductor materials. Because this semiconductor material has the characteristic of converting electrical energy into light, when an electric current is applied to this semiconductor material, the electrons inside it will combine with holes, and the excess energy will be released in the form of light to achieve luminescence. Effect. [0003] Generally speaking, due to the mismatch between the lattice constant of gallium nitride used as the material of the epitaxial layer in the light-emitting diode and the lattice constant of the sapphire substrate, the degree of the lattice constant mismatch is about 16%, resulting in A large number of defects are generated...

AI Technical Summary

Problems solved by technology

[0004] However, when the light-emitting band of the light-emitting diode gradually shifts from the blue light to the ultraviolet light band, since the indium content in the active layer gradually decreases, the formation area of ​​indium self-agglomeration is relatively reduced, which makes the carriers in the light-emitting diode easy to Moved to the defect to produce non-radiative recombination, resulting in a significant reduction in the luminous efficiency of the light-emitting diode in the near-ultraviolet light; moreover, the nitride semiconductor itself has a polarization field effect that causes the energy band of the active layer to bend, and the electron-hole pair is not easy to be absorbed. Confined inside the quantum well layer, thus unable to radiatively recombine efficiently

In addition, electrons are more likely to overflow (overflow) to the P-type semiconductor layer, resulting in a decrease in luminous intensity. Furthermore, since the mobility of holes is smaller than that of electrons, when holes are injected from the P-type semiconductor layer into the active layer, the Most of the holes are confined in the quantum well layer closest to the P-type semiconductor layer, and it is not easy to distribute uniformly in all the quantum well layers, resulting in a decrease in luminous intensity. Therefore, the industry strives to develop light-emitting diodes with high luminous intensity.

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