Prior to 1990: Red, Orange, Yellow and Yellowish Green.
Early 1990s: Silicon Carbide (SiC) Blue
Mid 1990s: Gallium Nitride(GaN)-Blue, Indium Gallium Nitride(InGaN)-Green
(Shuji Nakamura of Nichia Corporation)
Current LEDs use GaN/InGaN for Blues/Greens, Aluminum Indium
Gallium Phosphide (AlInGaP II) for Reds/Oranges/Yellows.
Prior to 1990, the only LED colors available were red, orange, and yellow. At best, a very yellowish-green was available. As a result, the color gamut covered by these LEDs was quite small. LEDs were only used as indicator lights and in their traditional field of high-maintence applications.
In 1990, the first Blue LED was created using SiC. While this was a milestone, the SiC LED had a very short lifespan and gave off very little light. A few years later, Shuji Nakamura of Nichia Corporation created the first "super-bright" blue and green LEDs from GaN and InGaN, creating the other 2 base colors required for full color applications.
