The Study Of The Ultraviolet Light Emitting Diode Used To Sensors

This research addresses the development of the AlGaN-based ultraviolet light emitting diodes(UV-LEDs). UV-LEDs have a lot of applications such as the purification of water, free space non-line of light communication and fluorescent identification of biological systems. The recently reports indicate that such devices are lowly efficient, a reason can be the low internal quantum efficiency, the low carrier injection efficiency, the low light extraction efficiency, or there are three factors together. My research focuses on the development of UV-LEDs based on AlGaN grow on sapphire substrates and addresses material issues such as the defects as well as device issues the low internal quantum efficiency and the low carrier injection efficiency.To enhance the internal quantum efficiency, I develop the bang structure potential fluctuation in the AlGaN quantum well layers. The reasons of such potential fluctuations are lateral compositional inhomogeneities of the AlGaN alloy or partial ordered alloy, where the ordered parts have a smaller bang gap than the random parts. The injected electron and hole pairs in the active region are in the minima of such potential fluctuations and become excitons, and so avoided from migrating to and recombining non-radiatively at dislocations.To improve the low carrier injection efficiency, I optimize the structure of the layers. Using AlGaN/AlGaN super lattice as the P-type layer that can reduce the resistance and enhance the carrier injection efficiency. Growing a AlN buffer layer of thick more than2μm can obviously reduce the crack of highly doped n-AlGaN with Si to enhance the carrier injection efficiency.