In Situ AlGaN Interlayer for Reducing the Reverse Leakage Current of InGaN Light-Emitting Diodes

The leakage current significantly affects the indium gallium nitride (InGaN) light-emitting diodes (LEDs) devices. In this work, we demonstrate a facile and compatible method to reduce the leakage current in InGaN LEDs by in situ inserting an aluminum gallium nitride (Al0.25Ga0.75N) interlayer before the growth of n-GaN. The reverse leakage current at -8 V is 37% lower compared to that of the LEDs without an AlGaN interlayer, while other electronic properties are comparable. The large bandgap of AlGaN hinders the carrier transportation towards substrate. From atomic force microscopy (AFM) and transmission electron microscopy (TEM) results, we found that the AlGaN interlayer dramatically blocks the propagation of threading dislocations (TDs), thus reducing the leakage current. This approach provides a practical strategy for effectively suppressing the leakage current in InGaN LEDs.