In the present study, embedded photonic crystals were introduced into the p-GaN contact layer of light-emitting diodes to increase the light-extraction efficiency of flip-chip deep-ultraviolet light-emitting diodes. As demonstrated by performing three-dimensional finite-difference time
domain simulation, the embedded photonic crystals could be designed to increase the total reflectivity on the p-GaN contact layer, thereby increasing the light-extraction efficiency. In addition, the effects of the embedded photonic crystals configurations on the light-extraction efficiency
of deep-ultraviolet light-emitting diodes were examined. Light-extraction efficiency over 21% for transverse magnetic polarized emission could be generally expected by rigorously optimizing the active layer position, as well as the depth, period, and filling factor of photonic crystals. Moreover,
an investigation was conducted on the light-extraction efficiency over the whole ultraviolet spectrum, and more light-extraction efficiency harvest on a broadband ultraviolet spectrum has been achieved as compared with flip-chip planar deep-ultraviolet light-emitting diodes. The optimized
structure will be promising for increasing the light-extraction efficiency of AlGaN-based flip-chip deep-ultraviolet light-emitting diodes.
Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate
