International research: InGaN quantum wells in the limitations of LED

Indium gallium nitride (InGaN) is a key material of blue LED, the recent international research team published on InGaN thin films of indium (Indium) core mechanism content limited, the study published in the Journal of January in "Physical Review Materials".

In order to make the III nitride LED a RGB color in red and green, usually increase the InGaN Quantum Well (Quantum Wells) in indium content. But the latest study found that the traditional method of indium content and can not draw red LED efficient and green LED.

Although the green LED and laser technology have progress, researchers are still unable to overcome the indium gallium nitride, indium concentration limit problem 30%, but for unknown reasons, cannot be determined by the growth of the environmental impact or basic factors. Until January of this year, the international research team in Germany, Poland and Chinese researcher on composition of indium content limited to explain, and further explained the mechanism of this limitation.

The study pointed out that scientists to challenge the indium content limit, so in gallium nitride (GaN) on the growth of indium nitride (InN) single atomic layer, but the experimental results show that the concentration of indium has been stuck in the 25% to 30%, and can not continue to rise, this is not limited to the indium content shows the environmental impact, but InN restriction mechanism itself.

The researchers used advanced atomic resolution transmission electron microscopy (Transmission Electron, Microscope, TEM), reflective high energy electron diffraction (Reflection High-Energy Electron Diffraction, RHEED) and other ways to observe, when the indium content reaches 25%, the arrangement and distribution of InGaN monolayer regularly, namely monatomic columns and two gallium the atomic columns are arranged alternately.

Through the comprehensive inference calculation can be learned, because atomic order specific surface reconstruction (surface reconstruction) and indium atoms do not three atomic bonding, but the bonding of four adjacent atoms, which makes indium and nitrogen atoms have stronger chemical bonds, and such characteristics azotize indium gallium can be grown in a high temperature environment, the material quality is better. However, in the sort of indium content can only reach 25%, which is in general growth conditions can not overcome the limitation.

Dr. Tobias Schulz of the research team said that the limitations of indium content lead indium gallium nitride cannot stimulate red and Huang Lvguang, so we need new ways to solve. (text: LEDinside Annie)

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