Simultaneously Enhancing Internal and Extraction Efficiencies of GaN-Based Light Emitting Diodes via Chemical-Wet-Etching Patterned-Sapphire-Substrate (CWE-PSS)

摘要

We report a chemical-wet-etching patterned-sapphire-substrate (CWE-PSS) that simultaneously enhances internal quantum efficiency and light extraction efficiency of gallium nitride based light-emitting-diode (LED). According to transmission electron microscopy (TEM) images, the threading dislocations penetrating into active region was dramatically reduced in the CWE-PSS structure compared to the planar sapphire substrate, i.e. enhancement of internal quantum efficiency. And according to the measurement of angular dependent diffraction power, CWE-PSS also serves as a diffraction grating which diffracts guided light into escaping cones, further improving light extraction efficiency of LED device.