Blue and green chip resolution used in LED display

Author: From: Time: 2019-10-10

The working principle of the LED is that in the case of forward conduction, the electrons and holes injected into the P/N section of the diode meet and combine to convert the potential energy into light energy. The wavelength of the emitted photon (that is, the color of the light) is determined by the band width of the semiconductor. Generally speaking, the wider the band width of the semiconductor, the larger the photon energy emitted, the shorter the corresponding wavelength, and the simple conversion relationship. Yes: (nm). The material basis of current blue and green LED devices is a group III nitride semiconductor, which is a quaternary AlGaInN alloy system mainly composed of GaN and supplemented by InN and AlN.

​At present, the quantum well luminescent layer material of most blue and green LED chips is composed of InxGa1-xN alloy and GaN. Since the band width of InxGa1-xN alloy varies with the ratio x of InN, it can be 3.4eV ( Corresponding to the band width of GaN) and 0.7 eV (corresponding to the band width of InN), so theoretically this material system can cover the entire visible spectrum. However, current material preparation techniques are based on epitaxial layer growth techniques of GaN crystals, and only alloy materials containing lower InN components can be grown. The InxGa1-xN alloy has a sharp drop in crystal quality after the composition of InN is x>15%. In fact, the current level of technology in the industry usually makes the electro-optical conversion efficiency of the blue chip about twice that of green light, because the former's InN component is much smaller than the latter, and the InN component of the green optical device is estimated to be 30. More than % (the determination of the precise composition of InGaN alloy materials is still a difficult scientific problem in academia). That is to say, the current technology is still difficult to continue to increase the composition of the InN, so that the InGaN alloy device can emit red light with high efficiency. Fortunately, as early as the 1990s, the Group III phosphide system (also commonly expressed as a quaternary system, AlGaInP) has become the mature material basis for red and yellow LED devices. The basic physical characteristics of the two material systems and the location of the elements they contain in the periodic table.