Progress on the GaN-based LEDs and LDs

The GaN-based light emitting diodes (LEDs) and laser diodes (LDs) have extensive applications in LED display, high brightness illumination, traffic signals, streetlights, automotive for LEDs, and high density optical storage, full-color display, laser printing, and laser lighting for LDs. The progress of the GaN-based LEDs and LDs is introduced. There are many universities and companies focusing on their research on the GaN LEDs and LDs, and the great breakthroughs have been achieved in the GaN material, process techniques, growth on non-polar and semi-polar substrates, and high extraction efficiency for LEDs. But there are still some challenges for the commercial applications such as selection of the appropriate substrates, quantum confined Stark effect (QCSE), and catastrophic optical damage (COD) for LDs. And the possible solutions are proposed in order to eliminate or decrease the difficulties.