One LED, four stable colors A research team has developed a terbium-doped AlGaN LED that emits blue, green, yellow, and red light from the same area, with no detectable wavelength shift as the drive current changes. (Nanowerk News) Full-color displays normally require separate red, green, and blue light emitters. However, conventional green and red nitride LEDs can show changes in color as the current increases. (Image: Shuhei Ichikawa)The team used a manufacturing method already widely employed for nitride LEDs to create aluminum gallium nitride LEDs containing terbium ions. Using color filters, the team was able to obtain red, green, and blue light separately from the same light-emitting area.