Emission and absorption
Electroluminescence from blue (blue) and green (green) light-emitting diodes was measured at a current of 20 mA. The blue diode emitted most strongly at 453 nm, while the green diode showed a peak at 520 nm. Photocurrent spectra were also measured by shining monochromatic light on the device. Both devices show a strong peak at 360 nm due to absorption by the surrounding material. Smaller peaks at 410 nm for the blue (cyan) and 420 nm for the green (yellow) diodes result from absorption by electron-hole pairs in the InGaN quantum well.