Blue LED
Refers to the blue LED. The center of the emission wavelength is around 470 nm. A light source for a blue display portion such as a lighting fixture and an indicator, a blue light source for an LED display panel, and a backlight source of the liquid crystal panel. Use in combination with a phosphor material to obtain white light. Current white LEDs generally use a combination of blue LEDs and fluorescent materials.
The opportunity for the wide application of blue LEDs was the first time in 1993 that Nichia Chemical Industry developed a variety of light intensity of more than 1 cd. Prior to this, there were no LEDs with high blue purity and practical light intensity. Therefore, a large-size display using LEDs cannot achieve full-color display.
The material of the blue LED uses a gallium nitride (GaN)-based semiconductor. In the past, blue LEDs were developed using zinc selenide (ZnSe) semiconductors. However, since the development of high-brightness blue LEDs using GaN-based semiconductors in December 1993, the mainstream of blue LEDs has become GaN-based. Semiconductor products.
The illuminating scene of Roma's blue LED.
The blue LED is configured such that an aluminum nitride (AlN) semiconductor layer and a GaN-based semiconductor layer are stacked on a surface of a sapphire or SiC substrate or the like. A structure in which a p-type GaN-based semiconductor layer and an n-type GaN-based semiconductor layer are overlapped is provided in a portion called an active layer and blue-emitting light.
The pn junction is the structure that must be used to make high-brightness LEDs. Among LEDs such as red, which use materials other than GaN, the pn junction is a mainstream structure long ago. Before the introduction of high-brightness blue LEDs in 1993, it was difficult to achieve pn junctions using GaN-based materials. The reason is that the formation of the n-type GaN-based semiconductor layer is relatively simple, but the fabrication of the p-type GaN-based semiconductor layer is difficult. After that, by using a multiple quantum well structure for the GaN-based semiconductor layer disposed between the p-type GaN-based semiconductor layer and the n-type GaN-based semiconductor layer, and further improving the quality of the GaN-based semiconductor layer, the light intensity is greatly improved.
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