Light emitting diode

Abstract

A light emitting diode including a sapphire substrate, a n-type semiconductor layer, an active layer, a p-type semiconductor layer, a first electrode, and a second electrode is provided. The n-type semiconductor layer is disposed on the sapphire substrate. The active layer has an active region, in which the defect density is greater than or equal to 2x10<SP>7< / SP> / cm<SP>3< / SP>. The active layer is disposed between the n-type semiconductor layer and the p-type semiconductor layer. The wavelength of light emitted by the active layer is λ , and 222 nm ≤ λ ≤ 405 nm. The active layer includes i quantum barrier layers and (i-1) quantum wells, each quantum well is disposed between any two quantum barrier layers, and i is an integer greater than or equal to 2. N-type dopant is doped to at least k quantum barrier layers within the i quantum barrier layers, wherein k is an integer greater than or equal to 1. When i is an even number, k is greater than or equal to i / 2. When i is a odd number, k is greater than or equal to (i-1) / 2. The first electrode and the second electrode are respectively disposed on the n-type semiconductor layer and the second semiconductor layer. Besides, a plurality of light emitting diodes are provided.

Description

[0001] This application is a divisional application, the application number of the parent application is 201310061155.1, the application date (the earliest priority date) is: March 1, 2012, and the invention name is "light-emitting diode". technical field [0002] 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 [0003] 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. [0004] Generally speaking, due to the mismatch between the lattice constant of gallium n...

AI Technical Summary

Problems solved by technology

[0005] 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.

Images