News: LEDs
10 May 2021
Nitride Semiconductors develops 12μm x 24μm micro UV-LED chips for displays
Picture: Chip size: 12μm x 24μm; chip spacing 5μm.
Nitride Semiconductors Co Ltd of Tokushima, Japan says that it has succeeded in miniaturizing micro UV-LED chips for micro-LED displays – which are expected to be used for next-generation augmented reality (AR) glasses and smart glasses – as well as developing mass-production technology.
For the next generation of liquid-crystal and organic LED displays, micro-LED displays are being developed by Apple in the USA as well as other companies in various countries. Red, blue and green micro-LED chips are being developed but, with existing methods, it is difficult to miniaturize the red LED chip to 50µm or less, so development has been encumbered.
Nitride Semiconductors says that it is progressing with the development of displays by using micro-UV (ultraviolet) LEDs to excite red, blue and green phosphors. Also, by putting them into practical use, the cost of micro UV-LED chips can be reduced, the firm adds.
Specifically, the firm has been working on developing micro UV-LED chips with a wavelength of 385nm, ahead of other companies, it is claimed.
Picture: Light emission from micro UV-LED chip (IF: 100μA; VF: 3.58V).
In the case of a conventional micro UV-LED, the chip size is 16μm x 48μm, the chip spacing is as wide as 10μm in the horizontal direction and 30μm in the vertical direction, and about 3.4 million chips can be obtained from a 4-inch wafer. When making a 25mm-square-size display, 300,000 micro-LED chips are required, so 11 micro-LED displays can be made from one wafer. By comparison, the newly developed micro UV-LED chip has a chip size of 12μm x 24μm, the chip spacing is 5μm in both the vertical and horizontal directions, and a 4-inch wafer can accommodate about 14 million chips (four times as many). Also, the cost per chip is a quarter of the conventional chip’s cost.
Nitride Semiconductors says that it has confirmed good electrical characteristics of the micro UV-LEDs and has made great strides toward practical application in the near future.
