Strain-adjusted LED can produce no phosphor white light

Chinese researchers say that if a (non fluorescent) strain-adjusted LED can be as efficient as an ordinary white LED, it can be a standard for testing LED.

Researchers at the Peking University (Beijing, China) are working on a "strain adjusting" GaAs layer to develop a gallium nitride white LED, which contains no phosphor, to produce blue and yellow light.

Although this is not the first time LED for such research, but researchers have carefully studied the origin of light, determine the light originating from the LED surface pits in the inverted Pyramid high-indium core area (yellow light emitting) and the adjacent indium-depleted areas (blue light emission). This crater is formed in the process of producing dislocations in the GaAs layer when processing strain-rELaxation.

The LED property is measured at room temperature by white light electroluminescence (EL) and cathodoluminescence spectroscopy research, at the same time, the high resolution x- ray diffraction and scanning electron microscope is used to help understand the relationship between optical properties and structure of equipment and the.

When the injection current is low, the LED is mainly yellow (560 nm) light. As the injection current increases, the blue (466nm) light will also increase, while the yellow light will eventually saturate. For example, when the current is 50mA, the LED issued a yellow light, but when the current is increased to 150mA, the EL spectrum is equivalent to a color temperature is 4972K, CIE chromaticity diagram is adjusted to 0.37, 0.37 white light source.

Ordinary white light LED is produced by the radiation of the blue light LED combined with phosphor converted yellow light, while the phosphor is excited by a part of the blue LED. If a (non fluorescent) strain-adjusted LED can be as efficient as an ordinary white LED, it is likely to become a new standard for testing white LED. What is the reason? It is likely that it will last longer because there is no phosphor to degrade it.