High Power AlInGaN-Based Deep Ultraviolet Light Emitting Diodes

Two complementary approaches to develop next generation of large area, high-efficiency and high-power deep ultraviolet light emitting diodes (DUV LED) are being proposed. Firstly, due to the lack of adequate quality native substrates, DUV LEDs are made from heteroepitaxial AlGaN films grown on foreign substrates and thus suffer from high-density of crystal defects. Large concentration of defects reduces deep UV LEDs’ efficiency, reliability and lifetime. Furthermore, poor conductivity of n-AlGaN causes current crowding problem for conventional square geometry LED design, which limits the device output power. We propose to develop large area, single-chip monolithic array DUV LEDs fabricated using low defect density AlGaN templates deposited over patterned sapphire substrates. Secondly, to enhance the external efficiency and power handling capability of DUV LEDs, we propose to develop vertical geometry devices using laser-assisted removal of sapphire substrate and fabrication of 2D photonic crystal using anodized Al technology.