A new LED manufacture method which does not require phosphor to make white semipolar LED was published by a research team of UCSB with Shuji Nakamura, Nobel winner and LED pioneer, as a co-author. The result was published in Optics Express.

White light emitting LEDs are usually made from blue LEDs combining yellow phosphor. But phosphor converted white LEDs usually suffer energy loss and reduced thermal stability. Phosphor-free LEDs, however, are rather difficult to fabricate but the UCSB team proposed an easier method to achieve efficient and polarized white semipolar LEDs which grown directly on GaN substrate.

The team adopted a top blue quantum well (QW) and a bottom yellow QW on semipolar bulk GaN substrate to produce phosphor-free white InGaN LEDs. These phosphor-free LEDs emitted peak wavelength of 427 nm in blue and 560 nm in yellow with an output power of 0.9mW.

(Image: (Li et al., 2020))

The researchers believe that the phosphor-free LEDs with advanced efficiency can be promising as backlight sources and offer possibility for Micro LEDs used in visible light communication (VLC, or light fidelity, LiFi).