Developed in the laboratory of Dr. Hongping Zhao this technology substantially enhances the light extraction efficiency of AlGaN quantum wells in deep ultraviolet (DUV) light-emitting diodes. The improvement relies on incorporating AlGaN microspheres on the p-AlGaN layer and using reactive ion etching to fabricate hemispherical-shaped surfaces into the layer. With such structures deployed in DUV LEDs three-dimensional finite-difference time-domain calculations were performed on the light extraction efficiency for both conventional LEDs with flat surfaces and DUV LEDs with AlGaN micro-spherical surface layers. The surface-altered DUV LED demonstrated a 7.3X enhancement of the dominant transverse magnetic (TM) component of polarized spontaneous emission as compared to that of the conventional LEDs. The far field pattern also showed significant enhancement of TM-polarized extraction efficiency for a wide range of polar angles. Thus the design of LEDs with this new technique has great potential to significantly enhance the total light extraction efficiency of DUV LEDs as well as for flip-chip structures and visible LEDs.
Significantly enhances the total light extraction efficiency of DUV LEDs as well as for flip-chip structures and visible LEDs.