A multiple quantum well (MQW) is the active, light-emitting region within semiconductor devices such as LEDs and laser diodes.
It is made up of multiple very thin semiconductor layers, or “quantum wells”, separated by barrier layers. These wells confine electrons and holes, allowing them to recombine efficiently and generate light.
In GaN-based devices, MQWs commonly contain indium (InGaN). The composition and quality of these layers play an important role in determining the wavelength, efficiency and light output of the device.