ITO/AlN rod-based hybrid electrodes: effect of buffer layers in AlN rods on performance of 365-nm light-emitting diodes

In this study, hybrid electrodes consisting of AlN rod arrays and surrounding indium tin oxide (ITO) films are proposed, and the effect of buffer layers in AlN rods on the performance of 365-nm light-emitting diodes (LEDs) is investigated. The AlN rod arrays were introduced in the form of ITO/AlN/buffer layers (Cr/Ni or thin ITO) to reduce the area and voltage for electrical breakdown (EBD), which is used to form conductive channels. The surrounding ITO film was used as a current spreading layer. Using this electrode design, we observed improved ohmic behavior and a higher transmittance at 365 nm compared to those of the reference ITO. In addition, both conduction and ohmic conduction mechanisms in the structure comprising a metal, AlN rod film, and p-AlGaN surface were investigated using various analysis tools. As a result, the 365-nm LEDs with thin Cr/Ni buffer layers exhibited a significantly higher light output power, lower forward voltages, and lower leakage currents than the LEDs with thin ITO buffer layers and reference ITOs.