A study of transparent contact to vertical GaN-based light-emitting diodes

In this study, transparent indium tin oxide (ITO) deposited by sputtering was applied to laser lift-off (LLO) GaN-based vertical light-emitting diodes (VLEDs) and the electrical and optical properties of ITO films were measured as a function of annealing conditions. The measured minimum resistivity of ITO film was about 3.78×10−4Ωcm and the measured optical transmittance at 460nm was 96.8% after the annealing process. In this condition, about 1×10−5Ωcm2 of ITO contact resistance to LLO n-GaN could be obtained. By applying the transparent ITO layer to the LLO GaN-based VLEDs, a significant decrease of the forward operating voltage from 3.3to3.8V at 20mA could be obtained.