GaN-Based Thin Film Vertical Structure Light Emitting Diodes Fabricated by a Modified Laser Lift-off Process and Transferred to Cu

GaN-based thin film vertical structure light-emitting diodes (VS-LEDs) were fabricated by a modified YAG laser lift-off (LLO) process and transferred to Cu substrates. With a comparison of the electrical and optical properties of conventional LEDs on sapphire substrates and of lateral structure thin film LEDs by a KrF LLO process, the vertical structure of LLO LEDs shows obvious superiority. LLO VSLEDs made by modified YAG LLO process show less increase of leakage current than the devices made by conventional KrF LLO process. Furthermore, owing to the well current spreading and less current path, the ideality factors and series resistance of vertical structure LEDs reduce greatly and the efficiency increases more obviously than the lateral structure LEDs, which is also reflected on the relative L–I curves. The output power of vertical structure LEDs is over 3 times greater than that of the lateral structure LLO LEDs within 300 mA.