Allow LED to achieve zero light decay?
University of Illinois at Urbana-Champaign researchers have developed a new method to improve the brightness of the green LED and improve its efficiency.
Assistant Professor of Electrical and Computer Engineering, University of Illinois Can Bayram develop a new method to improve the brightness of the green LED and improve its efficiency. (All Source: University of Illinois)
Using industry standard semiconductor crystal growth technique, the researchers on a silicon substrate manufacturing gallium nitride (GaN) crystal that can generate high-power green light, used in solid-state lighting.
Assistant Professor of Electrical and Computer Engineering, University of Illinois CanBayram said: “This is a breakthrough process, the researchers succeeded in the production of new materials with adjustable CMOS silicon process, which is a square gallium nitride (cubic GaN) , this material is mainly used for green wavelength emitter. “
The semiconductor for sensing and communications applications can open the visible light communication, and optical communication applications is the optical technology completely changed. Support LED CMOS process to achieve fast, high efficiency, low power and multiple applications at the same time the green LED can save a lot of costs process apparatus.
Usually one to two kinds of crystal structure formed of GaN, hexagonal or cubic. Hexagonal GaN is thermally stable, and is a traditional semiconductor applications. However, the hexagonal GaN are more prone to the phenomenon of polarization, the electric field inside the negative electrons and positrons separately to prevent them from binding, thus resulting in decreased light output efficiency.
So far, researchers have only been using molecular beam epitaxy (Molecular beam epitaxy) manufacturing square GaN, such a process is very expensive and contrast with the MOCVD process is very time-consuming.
The researchers successfully produced new materials on an adjustable type CMOS silicon process, which is a square gallium nitride (cubicGaN), this material is mainly used for green wavelength emitter.
Bayram said: “lithography (lithography) and anisotropic etching technology to produce U-line groove on the silicon layer which plays a non-conductive barrier to the hexagonal plastic square key role in our GaN no internal. electronic field can be separated, so the overlap may occur, electronic and pit more rapid binding and manufacture of light. “
Bayram and Liu believe their square GaN crystal may be able to successfully make LED light failure reaches zero (droop). Green, blue or UVLED, these LED luminous efficiency will be with the input current by gradually decline, also known as the light fades.
The study shows that the polarization has a pivotal position in the problem of bad light, the electron pushed away from the groove, especially in the case of low input current. In the case of zero polarization, square LED thicker towards more light-emitting layer and electron reduction and resolve overlapping recesses and current overload.
Better performance green LED will successfully opened new LED solid-state lighting applications. For example, the LED will emit white light by mixing and achieve energy savings. Other advanced applications also covers the use of non-fluorescent green LED manufacturing LED ultra-parallel applications such as optical communications, and water and genetics of migraine and other biotechnology applications.