Enhancement of External Quantum Efficiency of GaAs Light Emitting Diodes on GaAs Substrate with Photonic Crystal Structures

摘要

Near infrared light emitting diodes (LEDs) play an important role in infrared photodetectors; however external quantum efficiency of GaAs LEDs is greatly confined as a result of critical angle and Fresnel diffraction. In this study, polystyrene spheres are used to fabricate photonic crystal. A ring-shaped ohmic contact was introduced to the device, and the current-voltage curves and light emitting efficiency were measured to characterize the property of device. The LED device with surface nano-structure exhibited better external quantum efficiency (EQE) and improved light extraction efficiency (LEE) in near infrared light emitting area compared to non-structure device.