US researchers zoom trick, or let LED zero light?

Researchers at the University of Illinois at Urbana Champaign have developed a new way to increase the brightness of LED and improve its efficiency.

Bayram, assistant professor of electrical and computer engineering at the University of Illinois, Can, has developed a new approach to enhance the brightness of green LED and improve its efficiency. (source: University of Illinois)

Using the industry standard semiconductor long crystal technology, researchers on the silicon substrate to produce gallium nitride (GaN) crystals, which can produce high power green light, used in solid-state lighting.

The University of Illinois Department of electrical and computer engineering assistant professor Can Bayram said: "this is a breakthrough in the process, the researchers succeeded in producing new raw materials in the silicon CMOS process is adjustable on the square (cubic GaN), the GaN material is mainly used for green wavelength emitter. "

The semiconductor is used for sensing and communication to open the application of visible light communication, and optical communication is the technology to completely change the optical application. Support CMOS process LED can achieve fast, efficient, low power and multi application of green LED can save a lot of cost of process equipment.

Usually GaN forms one or two crystal structures, six squares or cubes. Six square GaN thermal stability, and the application of traditional semiconductors. However, the hexagonal GaN is prone to polarization, the internal electric field will be separated from the positron and negative electrons, to prevent them from combining, resulting in decreased light output efficiency.

So far, researchers have only been able to use molecular beam epitaxy (Molecular beam epitaxy) to create a square GaN, such a process is very expensive and compared with the MOCVD process is very time-consuming.

The researchers succeeded in the production of new materials on the adjustable CMOS silicon process, that is, GaN (cubic), which is mainly used for green wavelength emitter.

Bayram lithography technology (lithography) and isotropic etching technology to make U grooves on silicon. This layer of non-conductive barrier acts as a key role in shaping the hexagonal to square. Our GaN does not have an internal electric field capable of separating electrons and, therefore, overlapping problems may occur, electrons and holes more quickly combine and create light. "

Bayram and Liu believe they may GaN square crystal successfully let LED achieve zero attenuation (droop). On the green, blue or UVLED, the luminous efficiency of these LED will be with the current through the input gradually decline, which is also called light.

This study shows that the polarization has played an important role in the attenuation problem, the electronic push off groove, especially under the condition of low input current. In the case of zero polarization, the square LED is able to achieve a thicker light-emitting layer and solve the reduced electron and groove overlap as well as current overload.

Better green LED will successfully open a new LED solid state lighting applications. For example, these LED will be able to send white light by mixing and achieve energy efficiency. Other advanced applications include the use of non fluorescent green LED manufacturing super parallel LED applications, underwater communications, and other applications such as optical genetics and migraine.

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